How to Construct an Urban Color System? Taking the Historic Center of Macau as an Example

Abstract

This study focuses on the environmental colors of the Historic Center of Macau, seeking pathways to develop an urban color system to construct a high-quality urban aesthetic environment and enhance the overall visual image of the city. Based on Lenclos’s color geography and Shingo Yoshida’s environmental color planning method, this study conducted on-site color measurement, extraction, photographic documentation, numerical analysis, and color cataloging of the architecture, plazas, landscapes, and primary public facilities in Macau’s historical district. Through comprehensive environmental color investigation and analyses, the study aimed to construct a color system for Macau’s historical district, finally identifying 60 characteristic colors emblematic of the area. This study also uncovered issues, such as the lack of a unified management mechanism for environmental colors, insufficient coherence and correlation among regional colors, or the scarcity of striking colors. Ultimately, the proposed systematic approach to urban color can offer effective concepts for planning, design, and management, facilitating the creation of color expressions that align with Macau’s unique characteristics and thereby elevating the city’s overall visual image.

1. Introduction

Since its inclusion as a World Cultural Heritage site in 2005, the Historic Center of Macau has garnered continual attention, particularly in terms of its spatial configuration, architectural characteristics, and cultural promotion activities. The ‘Outline Development Plan for the Guangdong–Hong Kong–Macao Greater Bay Area’, released in February 2019 by China, underscores Macau’s historical urban significance and its unique historical heritage, marked by a rich and diverse cultural coexistence. As defined by the United Nations Educational, Scientific, and Cultural Organization (UNESCO), world heritage sites are categorized into natural and cultural heritages, the latter being further subdivided into monuments, architectural works, and sites. The United Nations General Assembly’s ‘2030 Agenda on Sustainable Development’, adopted in 2015, integrates the protection of cultural and natural heritages, advocating for interaction with nature and the essential necessity of maintaining a balance between them [1]. Macau’s Special Administrative Region’s Law No. 11/2013 on Cultural Heritage Protection mandates the implementation of suitable measures to ensure the compatibility of policies fostering economic growth and social advancement with those safeguarding cultural heritage. This approach is intended to promote comprehensive, harmonious, and sustainable development in Macau. It also encourages systematic data collection and facilitates access for Macau’s residents, interested parties, and related international organizations to such information [2].

The Historic Center of Macau primarily encompasses all significant buildings from the Portuguese colonial era in Macau, characterized by a diverse range of architectural styles and patterns, showcasing a distinct fusion of Chinese and Portuguese cultural elements [3]. Within the cityscape, the coloration of buildings constitutes an essential aspect of the city’s culture and style, significantly influencing the emotions of its inhabitants [3]. The composition of environmental colors not only epitomizes the unique characteristics of a historic and cultural city but also creates an iconic environmental landscape. The environmental colors also draw visual attention, guide movement directions, and become a part of the dynamic visual interaction [4].

Color is one of the most significant features guiding visual attention, with the basic level of color experience being the biological reaction to color stimuli [5]. Urban colors are essential in shaping people’s perception of a city’s appearance [6]. Serving as one of the dimensions of visual communication, color is crucial in fostering a sense of place identity and environmental experience [7]. It is regarded as an important factor in developing a sense of place, belonging, and the psychological imagery of a city [8]. Gerhard Meerwein and colleagues have proposed that an awareness of the psychological and physiological responses to color could inform a more socially responsive approach to color design, thereby increasing user satisfaction with the visual quality of urban environments [9].

Since 1978, the international academic community has regarded urban color planning as a platform for restoring the color identity of cities with historic centers, ensuring color consistency in expanding regions, and enhancing the city’s image [10]. Notable scholars in this field include French colorist Jean-Philippe Lenclos, founder of the Geography of Color, which emphasizes the investigation and summarization of urban colors. Lenclos identified the uniqueness of landscape colors based on their geographic, meteorological, luminous, cultural, historical, and technical influences [11]. The Geography of Color primarily employs methods such as investigation, color measurement recording, verification, induction, cataloging, and summarizing regional color characteristics, playing a vital role in color selection and guidance in urban planning, architectural and environmental landscape design, and modern industrial products. Moreover, Werner Spillmann, among the pioneers of incorporating color into architectural design, introduced a conceptual color design method. Werner’s approach evaluates and plans colors from psychological, sociological, and cultural standpoints, tested in practical applications. Werner’s design philosophy is exemplified in the color scheme of Kirchsteigfeld, Germany, where color is used not only for individual building facades but also for the continuity, integrity, and diversity of regional spaces and facades [12], emphasizing the logical relationships in the architectural environment. Japanese environmental color planning expert Shingo Yoshida categorized environmental colors into three main types: natural, social, and cultural environments, with further detailed subdivisions. Shingo delineated the scope of environmental color considerations to include public spaces, buildings, transportation, corporate identities, signage, shopping districts, residential areas, hotels, and nighttime settings, proposing specific color planning schemes for each category.

Current international research in the field of urban color primarily focuses on the investigation, analysis, planning, design, and construction of buildings, yet there is a notable absence of a comprehensive approach to constructing urban color systems. This research centers on the core area of the Historic Center of Macau, undertaking a detailed exploration and analysis of its environmental colors to develop an environmental color system for the area. This system is intended to provide more accurate references for urban planning and color design practices. Beyond its functional role, colors also foster heritage values and collective identity [13]. The specific objectives of this study are as follows: firstly, to understand the cultural background and color information of the Historic Center of Macau through the review of relevant literature; secondly, to conduct field investigations and record the environmental colors of the Historic Center of Macau, extracting color data, and converting, integrating, analyzing, and cataloging these colors; thirdly, to refine and summarize the representative colors of the color system of the Historic Center of Macau; fourthly, to identify and address the shortcomings in the current color planning of Macau’s historical urban environment, proposing improvements.

2. Relevant Theoretical Basis

2.1. Relevant Studies on Urban Color

Within the academic community, studies on urban color have been engaged across various domains. This study primarily concentrates on perspectives related to urban color within the fields of urban planning and design, design studies, urban studies, and landscape planning. The specifics are outlined below.

An in-depth and effective analysis of the color schemes of urban facades leads to the proactive exploration of color coordination schemes. This involves utilizing advanced image information technology for building identification, facilitating color extraction, and matching. The application of GIS-based methods for spatial sensitivity analysis significantly enhances the harmonization and control of urban colors in city color planning. Furthermore, the combination of architectural colors places a strong emphasis on the significance of the relationship between color and emotion.

First are the applications of urban color within architectural design. These include the exploration of strategies for planning and maintaining the colors of urban architecture. It is essential to preserve the original natural color palette of the architectural landscape while resisting the tendencies toward excessive preservation and the creation of “pseudo-historical” views in the planning of urban historical district landscapes. On the basis of in-depth and effective analysis of the colors of urban facades [14], the utilization of intelligent image information technology for building identification facilitates proactive color extraction and matching [15]. The application of GIS-based spatial sensitivity analysis methods enhances the coordination and control of urban colors in city color planning [16]. Furthermore, the significance of the relationship between color and emotion in the combination of architectural colors is emphasized [17].

Second, the application of urban color in environmental landscape planning is highlighted. Plant color represents a significant aspect of urban green spaces, and conducting quantitative analysis on its characteristics can provide a basis for configuring plant colors. J. Yang, Wang, and Zhao employed Scenic Beauty Estimates (SBE) to assess the aesthetic appeal of the leaf colors of variegated plants, the results of which contribute to the creation of richly colored plant landscapes [18]. The color scheme of urban park landscapes also impacts user satisfaction [19]. D. Wang introduced a method of seasonal color coordination for ornamental plants in urban landscape construction based on climate temperature zoning. This method, by leveraging the differences in seasonal timing and duration, establishes seasonal color matching results for each landscape unit based on the NCS color values of various species in different seasons and the duration of these seasons. A weighted method is then used to evaluate the seasonal color coordination of each landscape unit, proposing NCS color values for ornamental traits of plant species, their viewing periods, landscape color coordination schemes, and the selection of plant species [20].

The third aspect is the application of urban color in the conservation of historical districts. The protection of historical heritage necessitates adherence to its authenticity, particularly regarding color accuracy and fidelity [21]. This includes assessing the visual comfort of architectural colors in historical districts [22]. In the restoration of urban historical architecture, color perception plays a critical role, namely, how the nominal color of decorative elements is perceived when placed against building facades with varying background colors [23]. Süvari et al. mapped environmental colors by collecting samples of color changes occurring through natural and human processes to determine average values related to color density. These colors can serve as references for new designs in settlement landscapes and architectural conservation activities [24]. Color and materials are recognized as symbols of a site’s history, playing a vital role not only in affirming historical identity and creating continuity but also in constructing new narratives for a site undergoing self-reinvention [25].

In a word, in the process of urban planning and design, color plays a crucial role. However, current literature rarely explores how to maintain urban individuality and sustainable development through the construction of urban color systems. Both urban architecture and environmental landscape planning, as well as design, significantly influence the appearance of cities and the real-life experiences of their inhabitants. Research into the construction of urban color systems will better facilitate the inheritance of urban culture and sustainable development.

2.2. The Geographic Culture of the Historic District of Macau

The Age of Discovery, which spanned the late 15th to the early 16th century, marked the beginning of globalization. Portugal, located on the western coast of the Iberian Peninsula, played a significant role in the European imperialist and colonial invasion of the Eastern world. For the purposes of religious colonization and economic and trade expansion, Portugal established many colonies across Asia, Africa, and the Americas, including East Timor, Malacca, Macau, Angola, Brazil, and Uruguay. Macau, situated along the southeastern coast of China at the Pearl River Delta’s outlet, adjacent to Zhuhai in Guangdong, boasted both a vast continental hinterland and convenient external connections. Its unique geographical advantages made it a Portuguese colony. In 1557, the Portuguese claimed Macau as China’s first European territory, primarily serving as a center for trade and Catholic missions [26]. The arrival of the Portuguese in Chinese territorial waters signified the introduction of foreign commercial and religious cultures, which would become the cultural genes of Macau’s urban construction [27]. Thus, Macau’s urban structure, facing the continent while also oriented toward the sea, integrates Western culture with Chinese traditional Taoist and Lingnan cultures, ultimately forming the Historic District of Macau. This area fostered a multifunctional urban pattern encompassing residential settlements, religious beliefs, and security defense.

2.3. Exploration of the Approach to Constructing the Urban Color System of Macau

Color, possessing the flexible and transient capability to respond to both the continuity and multiple demands of urban spatial characteristics, offers a potential way to coexist between the needs for continuity and renewal [28]. Yifeng Xin [29] argued that there are primarily two international approaches to the investigation of environmental color, as illustrated in Figure 1. Each method has its unique characteristics. The environmental color investigation method represented by Jean-Philippe Lenclos from France focuses more on color analysis and induction after the survey, thereby generating color concepts. The CPC agency color investigation method from Japan emphasizes practical application, providing strategies for specific environmental color planning. Both approaches consider the influence of the geographical environment on color, but they differ in their operational focus—one emphasizes the impact of the landscape’s geographical environment on color, while the other concentrates on the categorization of urban environmental colors.

3. Methodology

3.1. Range of Investigation

The Historic Center of Macau comprises two main parts. The core area primarily includes 8 squares and 22 designated historic buildings, along with the streets that connect these squares and historic buildings. The second is the buffer zone surrounding the core area, which preserves the historical ambiance of the district, including its distinctive urban structure, spatial layout, and streetscapes, as well as many buildings of historical and cultural value. Therefore, the Historic Center of Macau is constituted by both the core area and the buffer zone, carrying the urban context and distinctive urban style of Macau.

On this basis, this study focused on the 8 squares and 22 buildings within the Historic Center of Macau as the main research samples. The eight forecourts include: the Barra Square, Lilau Square, St. Augustine’s Square, Senado Square, Cathedral Square, St. Dominic’s Square, Company of Jesus Square, and Camões Square. The 22 historic buildings are primarily: A-Ma Temple, Moorish Barracks, Mandarin’s House, St. Lawrence’s Church, St. Joseph’s Seminary and Church, Dom Pedro V Theatre, Sir Robert Ho Tung Library, St. Augustine’s Church, “Leal Senado” Building, Sam Kai Vui Kun, Holy House of Mercy, the Cathedral, St. Dominic’s Church, Ruins of St. Paul’s, Na Tcha Temple, Old City Walls, Monte Forte, St. Anthony’s Church, Casa Garden, Cemitério Protestante, and Guia Fortress (including Guia Lighthouse and Chapel of Our Lady of Snow). The specific spatial distribution is illustrated in Figure 2.

3.2. Research Procedure

The environmental color investigation primarily involves the on-site color extraction, color measurement, photographic documentation, and subsequent unified analysis of color values for buildings, squares, streets, landscapes, and major public facilities within the designated research scope of the Historic Center of Macau. This process extracts characteristic colors that can represent the distinctive features of the Historic Center of Macau. This study focused on the experiences gained from color planning and Jean-Philippe Lenclos’s color geography, on one hand, and on the other, it concentrated on the diverse and varied experiences developed from the concepts and practices in the current conditions of the Historic Center of Macau. Through the detailed investigation procedure, the main information about the historic district environment was derived, thereby constructing the color system of the Historic Center of Macau and formulating strategies for the preservation of related historical heritage. The survey process established based on the motives and purposes of this study is illustrated in Figure 3.

• Select color measurement object

The specific objects of color measurement involved in this study are summarized and compiled based on the established research scope and environmental color classification methods. Cultural environmental colors include the exterior colors of 19 historic buildings within the study area, the colors of 8 squares, and festival colors, natural environmental colors include the colors of plant landscapes, and social environmental colors cover the colors of public facilities.

2.

On-site observation and recording

This study conducted investigations on the eight officially announced square spaces to gain a more systematic and accurate understanding of the color situation in the Historic Center of Macau. The eight squares are arranged from south to north, as follows: Barra Square, Lilau Square, St. Augustine’s Square, Senado Square, Cathedral Square, St. Dominic’s Square, Company of Jesus Square, and Camões Square. The study focused on the architectural buildings of the plaza spaces and the color situation of the environmental blocks, including the urban green landscape. Referencing the “Introduction to Environmental Design Studies—Its Introduction Process and Prospects” [30], the environmental scale was divided into three investigative levels: large, medium, and small, with a special focus on historic buildings with dominant colors. Residential homes, public facilities, and buildings whose main colors could not be identified were excluded on-site, mainly measuring the main, secondary, and accent colors of the architectural and landscape environment.

Specifically, primary environment colors are those that represent the main characteristics of an environment, typically being the most prominent colors found in the natural surroundings and architectural styles. Secondary environment colors are used as complementary or accent colors, such as the colors of doors, windows, and decorations, to enhance the diversity and vibrancy of the primary elements.

The color of the garden landscape is much more complex than that of building colors due to its many instabilities, such as changes in seasons and climate effects, which can lead to significant differences in color presentation. Moreover, some vegetation may present different colors at different stages of growth. Therefore, this study recorded the color information of relevant landscape vegetation in a certain season and a relatively constant time and state. For the investigation of garden vegetation, this study referred to “Flora of Macau” [31,32] published by the Civic and Municipal Affairs Bureau of the Macau Special Administrative Region as a reference for plant types and names.

The investigation for this study was conducted between August and September 2021. To maintain a relatively constant state of colors, the time chosen for recording and comparing colors was consistently in the morning from 9 AM to 12 PM on sunny days. This time period offers abundant sunlight, ensuring even lighting on the surfaces of objects and fully showcasing the form and structure of the objects.

3.

Extract color

The objective of extracting colors is to fully capture the color information of a specific area, necessitating the choice of an appropriate color system. Each color system has its own focus, strengths, and weaknesses. The mainstream color systems in academia include several key types: The Munsell Color Order System (1905, United States), a system for the classification and standardization of colors introduced by the United States. The Ostwald Color System (1920, Germany), a color system developed in Germany. The Japanese Color Research Institute’s PCCS Color System, a practical color coordination system unique to Japan. The Swedish NCS Color System (Natural Color System, 1979), a color system built based on human visual perception of colors. The CIE Color System (1931), a method of color representation published by the International Commission on Illumination, pertaining to the subtractive color mixing optical representation. The DIN Color System, a color system published by the German National Standard Color Association after World War II.

After conducting a comprehensive comparison of the color systems mentioned above, this study found that the PCCS color system integrates the advantages and disadvantages of both the Munsell Color Order System and the Ostwald Color System. It incorporates the psychological primary colors as the foundation of the color system and has developed a color semantic scale, effectively systematizing color classification and considering the basic human emotional response to color. This color system is widely used internationally in environmental color research. Therefore, this study adopted this color system as the theoretical basis for investigating and analyzing the environmental colors of Macau.

Color extraction tools typically include color charts and instruments. Commonly used color charts include the Swedish NCS, Pantone colors from the United States, and the Japanese DIC color charts (DIC Corporation, Tokyo, Japan). Among these, the Pantone color chart is a widely used color guide. Its colors can match the four-color printing process and are based on the principles of subtractive and additive color mixing. It can also be applied to six-color printing or for mixing special colors, and even converting to digital display color mixing to produce the closest match. The application fields of the Pantone color chart are very wide, including the textile industry, plastics industry, construction industry, and more. Therefore, this study utilized the 2014 version of the PANTONE FORMULA GUIDE Uncoated, along with a PANTONE color measuring instrument and a Cube real color sensor. The PANTONE color measuring instrument can detect colors closest to PANTONE codes, while the Cube real color sensor can detect many colors that are not perceivable by the human eye and provides a range of values, including RGB primaries, CMYK print colors, web design #HEX, industrial use Lab, and reflectance LRV. These instruments help reduce human error in the comparison process, thus improving the efficiency of environmental color extraction. In the specific process of color extraction, three individuals form a group to compare the same color simultaneously, minimizing subjective errors and making the color results as objective and accurate as possible. Instruments can verify the results of paper color chart extractions, thereby further enhancing the accuracy of the colors.

In terms of objects from which accurate color information cannot be directly extracted, such as certain landscape greenery or public facilities with uneven materials, the FUJIFILM X100F camera was used in automatic mode P, uniformly taking photographs for documentation from 9 AM to 12 PM on clear weather days, saving them in JPG format. Then, the corresponding images were color-sampled using Illustrator, selecting three, six, or twelve colors based on the appearance of the subject as a reference for subsequent research.

4.

Convert colors and consolidate

The main color measurement tools in this study include the PANTONE color chart and color extraction devices. The PANTONE color chart only indicates the ink mixing values of colors and cannot be used directly for research. Therefore, the first step was to convert the PANTONE color chart values into corresponding RGB values through software. The specific operation involved using the software developed by PANTONE (The Classic Software to Manage Pantone Color Libraries in Adobe®, Sku#: DWNLD-PS-CM100), selecting the specified color swatch within the program, and finding the electronic color code corresponding to the values on the paper color chart to obtain the corresponding RGB values as standards. Then, these RGB color values were converted into Munsell values through the mobile app (mConverter). The specific steps are illustrated in Figure 4.

Through the previous steps, this study extracted the Munsell values of colors from the subjects under investigation, serving as a basis for environmental color analysis. Integrating the collected color information, this study organized the data according to the actual situation, removing messy elements, and primarily selecting representative color information for summarization.

5.

Color analysis

After establishing the color database, this study utilized the Munsell color chart to obtain the color chroma distribution of survey data. Subsequently, the survey data were categorized by the proportion of hues, using a hue proportion chart to determine the distribution of hues. The “Kumamoto Color Guide—Landscape Color Guidance Manual” [33] classifies all colors into four levels of chroma: achromatic, low chroma, medium chroma, and high chroma. Based on specific requirements, this study modified this classification into 11 types of tones (bright stable, medium stable, dark stable, bright clear, dark clear, bright, white, bright grey, medium grey, dark grey, and black).

6.

Color coding

The color-coding work was primarily based on the induction method of the Munsell color system, following the sequence of hues and the classification of tones: R (Red), RY (Red-Yellow), Y (Yellow), GY (Green-Yellow), G (Green), BG (Blue–Green), B (Blue), BP (Blue–Purple), P (Purple), RP (Red–Purple), and N (Achromatic colors), thereby establishing a conceptualized color atlas.

4. Result Analysis

4.1. Site Survey and Research Analysis

4.1.1. Architectural Color Analysis

The architectural color survey of the Historic Center of Macau in this study primarily encompassed 19 buildings, including 14 Western-style buildings and 5 Chinese-style buildings, with specific color information illustrated in Figure 5.

This study’s architectural color analysis of the Historic Center of Macau summarized 19 buildings, from which a total of 75 colors were extracted, including 21 main colors and 54 secondary colors.

The main colors of the architectural colors in the Historic Center of Macau mainly came from the exterior facades of buildings, with the color range concentrated in the hues of YR (Yellow–Red), Y (Yellow), G (Green), BG (Blue–Green), PB (Purple–Blue), and N (Achromatic). The secondary colors were primarily derived from architectural elements, such as doors, windows, railings, and exterior wall decorations, with the color range focused on R (Red), YR (Yellow–Red), Y (Yellow), G (Green), BG (Blue–Green), B (Blue), PB (Purple–Blue), RP (Red–Purple), and N (Achromatic). Combining the main and secondary colors formed a comprehensive chromaticity chart, concentrating the color range in the hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), BG (Blue–Green), B (Blue), PB (Purple–Blue), RP (Red–Purple), and N (Achromatic). The largest proportion of colors consisted of Y (Yellow) at 22.7%, N (Achromatic) at 16%, and YR (Yellow–Red) at 16%, followed by R (Red), G (Green), BG (Blue–Green), PB (Purple–Blue), B (Blue), and RP (Red–Purple). The overall color tone was predominantly high-chroma and bright colors, making up 32%, mainly including bright colors, medium stable colors, and white, followed by bright clear colors, dark clear colors, dark stable colors, bright stable colors, and medium grey. Details are shown in Figure 6.

Finally, by integrating the collected colors and removing duplicates, a color atlas of architectural colors in the Historic Center of Macau was compiled, as specifically illustrated in Figure 7.

4.1.2. Square Environmental Color Analysis

1. Barra Square, located in front of the A-Ma Temple in the southern part of the Macau Peninsula, within the São Lourenço District, is named for its position in front of the A-Ma Temple and covers an area of approximately 4400 square meters. “Barra” in Portuguese means “barrier”, referring here to a barrier formed by the impact of river and sea water flow [34]. The square faces the sea and is adjacent to the Macau Maritime Museum, tourist boat pier, the Maritime Museum’s administrative building, with Ma Kok Lane to the north and connecting to Rua do A-Ma to the south. The environmental landscape color of the square is primarily based on the greenery planted in the square, the public facilities provided, and cultural lantern installations. The square mainly plants large woody plants, such as flame trees, false bodhi trees, banyan trees, papaya, poinciana, and fan palms, complemented by low-growing goosefoot shrubs. The public facilities in the square include nearby newsstands, guide maps, seats, etc., and cultural colors mainly consist of lantern installations during major festivals. Additionally, the square’s ground is mainly paved with Portuguese-style cobblestone tiles in wave patterns, showcasing Macau’s unique maritime cultural characteristics.

The environmental color analysis of Barra Square resulted in a total of 67 extracted colors, including 20 architectural colors, 18 public facility colors, 18 landscape colors, and 11 cultural colors. The color atlas compilation is shown in Figure 8.

The architectural colors of Barra Square primarily include the facades of the building, prominent facade decorations, doors, and windows. The colors are mainly concentrated in R (Red), YR (Yellow–Red), Y (Yellow), G (Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), and RP (Red–Purple), with YR (Yellow–Red) and Y (Yellow) being the most prevalent. This is mainly because the A-Ma Temple follows traditional Chinese temple architecture, with the overall base tone being gray, as shown in Figure 9a.

The colors of the public facilities at Barra Square include forecourt tiles, mail kiosks, tables, chairs, recycling bins, and trash cans. These are mainly concentrated in R (Red), YR (Yellow–Red), GY (Yellow–Green), G (Green), B (Blue), and PB (Blue–Purple), with the most in G (Green), B (Blue), and PB (Blue–Purple). This is mainly due to the larger number and volume of recycling bins in the forecourt, with mail kiosks and tables typically in Macau’s characteristic green. The tones are mostly low chroma and light stable, as shown in Figure 9b.

The landscape colors of Barra Square primarily involve the representative vegetation around the square, mainly concentrating in Y (Yellow), G (Green), and GY (Yellow–Green), with the most in GY (Yellow–Green). The tones are mostly medium chroma and dark clear, as shown in Figure 9c.

The cultural colors at Barra Square mainly include festive lanterns placed in the square and hanging flags, predominantly in R (Red), YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), BG (Blue–Green), PB (Blue–Purple), and RP (Red–Purple), with the most in R (Red) and YR (Yellow–Red). This is mainly due to the influence of traditional Chinese culture, which uses bright colors, such as red and yellow–green, during festivals to signify liveliness and celebration. The tones are mostly high chroma, as shown in Figure 9d.

Finally, the environmental colors of Barra Square are combined into a unified chromaticity chart, encompassing hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), RP (Red–Purple), and N (Achromatic), as shown in Figure 9e. GY (Yellow–Green) has the largest proportion at 26.9%, followed by G (Green), YR (Yellow–Red), R (Red), PB (Blue–Purple), Y (Yellow), B (Blue), and RP (Red–Purple), with the smallest being BG (Blue–Green) at 3%, as shown in Figure 9f. The overall tone displays high chroma at 62.7%, predominantly in bright, light clear, and dark clear colors, followed by light stable, medium stable, white, and stable tones, as detailed in Figure 9g.

Finally, by integrating the collected colors and eliminating duplicates, a color atlas of the environmental colors at Barra Square was compiled, as specifically illustrated in Figure 10.

2. Lilau Square, also known as Muddy Fountain (Portuguese: Lilau) and Dragon Head Well, is located in a square on the north side of Mount Guia in Macau, covering an area of approximately 635 square meters. Its name derives from historical legends involving a Portuguese fountain and a Chinese well: during the Ming dynasty, an elderly lady constructed a pond here to store mountain spring water for the local residents to draw for drinking, hence the name “Lilau”, which in Portuguese means “mountain spring”. This area was one of the earliest places where Portuguese settled and is surrounded by Portuguese-style ancient buildings. It has been designated as part of Macau’s architectural, historical, and cultural heritage district and is also listed in the World Cultural Heritage List. Lilau Square embodies the culture and memories of the Sino-Portuguese community. The environmental colors of the forecourt primarily include large woody plants, such as false bodhi trees, banyan trees, and magnolia, complemented by shrubs, such as red-backed laurel, elephant ear vine, ash, red flower madder, podocarpus, and bottle orchid. Public installations include newsstands, seating, and wall fountains.

The environmental colors of Lilau Square were analyzed to include a total of 46 colors, consisting of 16 architectural colors, 8 public facility colors, and 22 landscape colors. The color atlas is summarized in Figure 11.

The architectural colors of Lilau Square primarily include the main walls, doors, and windows of surrounding buildings, focusing mainly on R (Red), YR (Yellow–Red), Y (Yellow), BG (Blue–Green), PB (Blue–Purple), and N (Achromatic), with N (Achromatic) being the most prevalent. This is largely because the historic buildings near Lilau Square were traditionally inhabited by Portuguese, resulting in architectural color combinations such as yellow–white, red–white, and green–white, all exuding a European flair. The tones are mostly low chroma and dark stable, as shown in Figure 12a.

The colors of the public facilities at Lilau Square, including forecourt tiles, mail kiosks, tables, chairs, and public fountains, are mainly concentrated in R (Red), YR (Yellow–Red), Y (Yellow), G (Green), B (Blue), and PB (Blue–Purple), with YR (Yellow–Red) being the most common. The tones are mostly low chroma and medium stable, as illustrated in Figure 12b.

The landscape colors of Lilau Square, which mainly involve representative vegetation around the square, are concentrated in YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), and BG (Blue–Green), with GY (Yellow–Green) being the most prevalent. The tones are mostly medium chroma and dark clear, as depicted in Figure 12c. Finally, the environmental colors of Lilau Square are combined into a unified chromaticity chart, including hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), and N (Achromatic), as shown in Figure 12d. GY (Yellow–Green) holds the largest proportion at 30.4%, followed by YR (Yellow–Red), Y (Yellow), N (Achromatic), R (Red), G (Green), PB (Blue–Purple), and BG (Blue–Green), with the smallest being B (Blue) at 2.2%, as illustrated in Figure 12e. The overall tone exhibits high chroma at 52.1%, predominantly in bright, dark clear, and white colors, followed by dark stable, medium stable, light stable, and light clear colors, as detailed in Figure 12f.

Finally, by integrating the collected colors and removing duplicates, a color atlas of the environmental colors at Lilau Square was compiled, as specifically illustrated in Figure 13.

3. St. Augustine’s Square, located at the top of Mount Hill (historically known as Millstone Mountain) within the São Lourenço district on the Macau Peninsula, is a square that connects to Senado Square (via Travessa do Oriente), Rua da Felicidade, Rua Long Son, Rua da Palha, and Rua do Tung Sin Tong. The area also hosts a district police headquarters and the administrative center of Banco Comercial de Macau. Its Portuguese name is Largo de Santo Agostinho, covering an area of about 1060 m². The surrounding historic buildings mainly include St. Joseph’s Seminary and Church, Dom Pedro V Theatre, Sir Robert Ho Tung Library, and St. Augustine’s Church. The environmental landscape colors include banyan trees and soft-leaved hibiscus as woody plants, complemented by lower goosefoot vines and Ficus shrubs, with planters adorned with aspidistra and millet grass, among other herbaceous plants. Public installations include newsstands, seating, and a shrine to the Virgin Mary (as shown in the image), while the forecourt surface features Portuguese-style wave-pattern cobblestone paving, adding a European flair to the square.

The environmental colors of St. Augustine’s Square were analyzed to include a total of 51 colors, consisting of 14 architectural colors, 21 colors for public facilities, and 16 landscape colors. The color atlas is summarized in Figure 14.

The architectural colors of St. Augustine’s Square primarily include the main walls, doors, windows, and wall decorations of surrounding buildings. The colors mainly focus on Y (Yellow), G (Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), and N (Achromatic), with Y (Yellow), G (Green), BG (Blue–Green), and N (Achromatic) being the most prevalent. The tones mostly consist of medium-chroma and light clear colors, as shown in Figure 15a.

The colors of public facilities at St. Augustine’s Square include forecourt tiles, mail kiosks, tables, chairs, recycling bins, the Virgin Mary shrine, and guideposts. These are primarily in hues of YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), G (Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), and N (Achromatic), with Y (Yellow) being the most common. The tones are predominantly medium chroma and light clear, as depicted in Figure 15b.

The landscape colors of St. Augustine’s Square focus on the representative vegetation around the square, concentrating mainly in R (Red), Y (Yellow), and GY (Yellow–Green), with GY (Yellow–Green) being the most common. The tones are primarily medium chroma and dark clear, as illustrated in Figure 15c.

Finally, the environmental colors of St. Augustine’s Square are combined into a unified chromaticity chart, including hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), and N (Achromatic), as detailed in Figure 15d. GY (Yellow–Green) has the largest proportion at 29.4%, followed by Y (Yellow), G (Green), BG (Blue–Green), YR (Yellow–Red), N (Achromatic), PB (Blue–Purple), and B (Blue), with R (Red) being the least at 3.9%, as shown in Figure 15e. The overall tone displays high chroma at 60.8%, predominantly in bright, dark clear, and light clear colors, followed by white, dark stable, medium stable, and light stable tones, as detailed in Figure 15f.

Finally, by integrating the collected colors and removing duplicates, a color spectrum of the environmental colors at St. Augustine’s Square is compiled, as specifically illustrated in Figure 16.

4. Senado Square, commonly known as the “Fountain”, is one of Macau’s four major squares. Located in the central district of the Macau Peninsula, it connects to Largo do São Domingos in the north and is adjacent to Avenida de Almeida Ribeiro in the south. The square is narrow and triangular, wider at the south and narrower at the north, covering an area of approximately 3700 square meters. It is the most bustling commercial and cultural activity area in Macau. During the colonial period, the newly appointed governors of Macau would hold review ceremonies of the Macau sea and land troops here. The statue of Portuguese officer Mesquita, once erected in the square, was destroyed and replaced with today’s fountain, giving rise to its common name. The surrounding notable buildings include the Civic and Municipal Affairs Bureau Building, Koi Kei Bakery, Macau Business Tourism Center, Holy House of Mercy, and Macau General Post Office Building. The environmental landscape colors mainly include woody plants, such as camphor trees, banyan trees, and fragrant camphor trees, complemented by shrubs, such as red flower madder, elephant ear vine, and Ficus, with planters adorned with millet grass and aspidistra, as well as yellow daisies hanging from streetlamps. Public installations primarily include public seats, and cultural colors mainly comprise lanterns and arches displayed during various festivals and major holidays. The environmental colors of Senado Square were analyzed to include a total of 97 colors, consisting of 17 architectural colors, 28 public facility colors, 28 landscape colors, and 24 cultural colors. The color atlas is summarized in Figure 17.

The architectural colors of Senado Square primarily include the main walls, doors, windows, and wall decorations of the surrounding buildings. These colors are mainly concentrated in R (Red), YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), G (Green), and N (Achromatic), with Y (Yellow) and N (Achromatic) being the most prevalent. The tones are mostly medium-chroma and light clear colors, as shown in Figure 18a.

The public facility colors at Senado Square include the forecourt tiles, mail kiosks, tables, chairs, recycling bins, and guideposts. These colors are mainly concentrated in R (Red), YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), G (Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), RP (Red–Purple), and N (Achromatic), with Y (Yellow) being the most common. The tones are predominantly medium chroma and light clear, as depicted in Figure 18b.

The landscape colors of Senado Square focus on the representative vegetation around the square, mainly concentrating in R (Red), YR (Yellow–Red), Y (Yellow), and GY (Yellow–Green), with GY (Yellow–Green) being the most common. The tones are primarily medium chroma and dark clear, as illustrated in Figure 18c.

The cultural colors at Senado Square include festive lanterns and installations placed in the square during celebrations. These colors are primarily concentrated in R (Red), YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), G (Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), and RP (Red–Purple), with R (Red), YR (Yellow–Red), and Y (Yellow) being the most prevalent due to the influence of traditional Chinese culture, which uses bright and high-purity colors, such as red and yellow–green, during festivals to signify liveliness and celebration. The tones are mostly high chroma, as shown in Figure 18d.

Finally, the environmental colors of Senado Square are combined into a unified chromaticity chart, including hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), RP (Red–Purple), and N (Achromatic), as illustrated in Figure 18e. GY (Yellow–Green) has the largest proportion at 24.7%, followed by Y (Yellow), YR (Yellow–Red), R (Red), G (Green), BG (Blue–Green), N (Achromatic), and PB (Blue–Purple), with RP (Red–Purple) and B (Blue) being the smallest at 4.1%, as illustrated in Figure 18f. The overall tone exhibits high chroma at 62.9%, predominantly in bright and dark clear colors, followed by medium stable, dark stable, white, dark clear, and light stable tones, as detailed in Figure 18g.

Finally, by integrating the collected colors and removing duplicates, a color spectrum of the environmental colors at Senado Square was compiled, as specifically illustrated in Figure 19.

5. Cathedral Square, commonly known as “Dai Mio Ting”, is the square in front of the Cathedral of the Nativity of Our Lady. It is situated on a small hill in Macau’s Nam Van area and can be accessed via Cathedral Street, connecting to Avenida de Almeida Ribeiro and linking with Rua Long Son. From the square, Travessa do Paço connects to Rua do Campo, Bishop Lane and Cathedral Lane connect to Rua de Santo António, and Travessa do Bispo connects to Senado Square. The area is approximately 821 square meters. The square is now paved with black and white stones in a Southern European style and features a fountain and a stone cross. Significant historical buildings surrounding the square include the Cathedral of the Nativity of Our Lady, the Bishop’s Office of the Macau Diocese, and Portuguese residential houses. The environmental landscape colors primarily include woody plants, such as flame trees, banyan trees, and fan palms, complemented by low shrubs, such as golden dewdrop, elephant ear vine, and ash, with herbaceous plants, such as hibiscus and cockscomb, in the flower beds.

The environmental color analysis of Cathedral Square resulted in a total of 46 extracted colors, including 19 architectural colors, 6 public facility colors, and 21 landscape colors. The color atlas is summarized in Figure 20.

The architectural colors of Cathedral Square primarily include the main walls, doors, windows, and wall decorations of the surrounding buildings. These colors are mainly concentrated in R (Red), YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), G (Green), PB (Blue–Purple), and N (Achromatic), with YR (Yellow–Red) being the most prevalent. The tones are mostly medium-chroma and light clear colors, as shown in Figure 21a.

The public facility colors at Cathedral Square include forecourt tiles and wall tiles, mainly concentrated in YR (Yellow–Red), PB (Blue–Purple), and N (Achromatic), with PB (Blue–Purple) being the most common. This is primarily due to the use of Portuguese tiles for wall decorations in Cathedral Square. The tones are mostly low-chroma and stable colors, including light stable, medium stable, and dark stable, as illustrated in Figure 21b.

The landscape colors of Cathedral Square focus on the representative vegetation around the square, mainly concentrating in R (Red), Y (Yellow), and GY (Yellow–Green), with GY (Yellow–Green) being the most prevalent. The tones are primarily medium chroma and dark clear, as depicted in Figure 21c.

Finally, the environmental colors of Cathedral Square are combined into a unified chromaticity chart, including hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), PB (Blue–Purple), and N (Achromatic), as illustrated in Figure 21d. GY (Yellow–Green) has the largest proportion at 32.6%, followed by Y (Yellow), PB (Blue–Purple), YR (Yellow–Red), R (Red), G (Green), and N (Achromatic), with BG (Blue–Green) being the smallest at 2.2%, as illustrated in Figure 21e. The overall tone exhibits high chroma at 60.9%, predominantly in bright colors, medium stable colors, and dark clear colors, followed by light clear, white, medium stable, and light stable tones, as detailed in Figure 21f.

Finally, by integrating the collected colors and removing duplicates, a color spectrum of the environmental colors at Cathedral Square was compiled, as specifically illustrated in Figure 22.

6. St. Dominic’s Square is a square located in the city center of the Macau Peninsula, specifically in front of St. Dominic’s Church. It connects to Senado Square to the south, links with Travessa do Meio to the west, and extends to Rua de São Domingos to the east, covering an area of approximately 587 square meters. In the 1990s, the Macau–Portuguese government paved the square with black and white cobblestones, turning it into a pedestrian-only zone in harmony with the surrounding streets. Occasionally, the square is used for gatherings, sit-ins to express demands, and various cultural and artistic activities, such as light festivals and Children’s Day celebrations. The main buildings surrounding the square include St. Dominic’s Church and commercial buildings with Portuguese architectural styles. The environmental landscape colors include the colors of large royal palms and fragrant camphor trees. Public installations feature seats and colorful apple promotional installations.

The environmental color analysis of St. Dominic’s Square resulted in a total of 22 extracted colors, including 11 architectural colors, 5 public facility colors, and 6 landscape colors. The color atlas is summarized in Figure 23.

The architectural colors of St. Dominic’s Square primarily include the main walls, doors, windows, and wall decorations of the surrounding buildings. These colors are mainly concentrated in YR (Yellow–Red), Y (Yellow), G (Green), and N (Achromatic), with Y (Yellow) being the most prevalent. The tones are mostly medium-chroma and light clear colors, as shown in Figure 24a.

The public facility colors at St. Dominic’s Square include forecourt tiles, tables, chairs, and notice boards. These colors are mainly concentrated in R (Red), YR (Yellow–Red), Y (Yellow), and PB (Blue–Purple), with YR (Yellow–Red) being the most common. The tones are predominantly medium chroma and light clear, as illustrated in Figure 24b.

The landscape colors of St. Dominic’s Square focus on the representative vegetation around the square, mainly concentrating in Y (Yellow), GY (Yellow–Green), and BG (Blue–Green), with GY (Yellow–Green) being the most prevalent. The tones are primarily low chroma and dark stable, as depicted in Figure 24c.

Finally, the environmental colors of St. Dominic’s Square are combined into a unified chromaticity chart, including hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), PB (Blue–Purple), and N (Achromatic), as illustrated in Figure 24d. Y (Yellow) has the largest proportion at 40.9%, followed by YR (Yellow–Red), N (Achromatic), GY (Yellow–Green), and G (Green). The smallest proportions are R (Red), BG (Blue–Green), and PB (Blue–Purple), each at 4.5%, as illustrated in Figure 24e. The overall tone exhibits both high chroma and medium chroma, each at 31.8%, predominantly featuring bright, dark clear, and dark stable colors, followed by white, dark clear, medium stable, and light stable tones, as detailed in Figure 24f.

Finally, by integrating the collected colors and removing duplicates, a color spectrum of the environmental colors at St. Dominic’s Square was compiled, as specifically illustrated in Figure 25.

7. The Company of Jesus Square is located in front of the Ruins of St. Paul’s on the Macau Peninsula, connecting to Rua de São Paulo, Travessa de São Paulo, Calçada de São Paulo, and Rua Direita de São Paulo. This square commemorates the Jesuit missionaries who established St. Paul’s College in Macau. It has now become one of Macau’s iconic landmarks, attracting tourists and serving as a venue for various events, celebrations, and outdoor photography. The square is characterized by a series of wide steps and adjacent sloping streets, with the main focal point being the Ruins of St. Paul’s. To the north, there is the Museum of Sacred Art and Crypt, and to the east is Mount Fortress, home to the Macau Museum. To the northwest of the square is the Na Tcha Temple. The environmental landscape colors primarily include plantings of elephant ear vines, red flower madder, and gold-edged boxwood, with sloping flowerbeds and one side planted with podocarpus, golden dewdrop, red-backed laurels, elephant ear vines, and crepe myrtle, with cockscomb flowerpots hanging on the edge of the flowerbeds.

The environmental color analysis of the Company of Jesus Square resulted in a total of 39 extracted colors, including 6 architectural colors, 2 public facility colors, 25 landscape colors, and 6 cultural colors. The color atlas is summarized in Figure 26.

The architectural colors of the Company of Jesus Square primarily include the main walls, doors, windows, and wall decorations of the surrounding buildings. These colors are mainly concentrated in YR (Yellow–Red), Y (Yellow), and B (Blue), with YR (Yellow–Red) being the most prevalent. The tones are mostly low-chroma and light stable colors, as shown in Figure 27a.

The landscape colors of the Company of Jesus Square focus on the representative vegetation around the square, mainly concentrating in R (Red), YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), and G (Green), with GY (Yellow–Green) being the most prevalent. The tones are primarily medium chroma and dark clear, as depicted in Figure 27b.

The cultural colors of the Company of Jesus Square mainly involve festive lanterns and installations placed in the flowerbeds beside the Ruins of St. Paul’s during celebrations. These colors are primarily concentrated in R (Red), Y (Yellow), PB (Blue–Purple), RP (Red–Purple), and N (Achromatic), with Y (Yellow) being the most common. The tones are mostly medium chroma and light clear, as shown in Figure 27c.

Lastly, the environmental colors of the Company of Jesus Square are combined into a unified chromaticity chart, including hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), B (Blue), PB (Blue–Purple), RP (Red–Purple), and N (Achromatic), as illustrated in Figure 27d. GY (Yellow–Green) has the largest proportion at 41%, followed by Y (Yellow), YR (Yellow–Red), G (Green), N (Achromatic), and R (Red). The smallest proportions are B (Blue), RP (Red–Purple), BG (Blue–Green), and PB (Blue–Purple), each at 2.6%, as illustrated in Figure 27e. The overall tone exhibits high chroma at 64.1%, predominantly featuring bright and dark clear colors, followed by light stable, white, medium stable, dark stable, and light clear tones, as detailed in Figure 27f.

To sum up, by integrating the collected colors and removing duplicates, a color spectrum of the environmental colors at the Company of Jesus Square was compiled, as specifically illustrated in Figure 28.

8. Camões Square, located in the northwest of the Macau Peninsula and to the north of the old town area, is a square in the St. Anthony Parish. Its Portuguese name, Praça de Luís de Camões, is derived from the grotto in Camões Garden, which honors the Portuguese poet Luís de Camões for his patriotism and achievements. The Chinese name comes from the 18th century, when a Portuguese merchant named Marquês lived here. Marquês kept white pigeons that nested in the eaves, resembling a dove’s nest from afar, hence the name. Significant historical buildings around the square include St. Anthony’s Church, the Protestant Cemetery, the headquarters of the Orient Foundation, and Camões Garden. The environmental landscape colors primarily include large trees, such as banyan, broad-leaved acacia, camphor, silk floss tree, ironwood, tall banyan, crape myrtle, and gold-edged boxwood, complemented by shrubs, such as red flower madder, elephant ear vine, Ficus, and hibiscus, as well as smaller herbaceous plants, such as peacock plant, variegated dumb cane, and red-backed laurel. Public installations include seating and mail kiosks.

The environmental color analysis of Camões Square resulted in a total of 63 extracted colors, including 4 architectural colors, 8 public facility colors, and 51 landscape colors. The color atlas is summarized in Figure 29.

The colors of public facilities at Camões Square primarily include the ground, public tables and chairs, mail kiosks, and the square’s clock. These colors are mainly concentrated in R (Red), YR (Yellow–Red), G (Green), PB (Blue–Purple), and N (Achromatic). The tones are predominantly low chroma and medium stable, as shown in Figure 30a.

The landscape colors of Camões Square focus on the representative vegetation around the square, mainly concentrating in YR (Yellow–Red), Y (Yellow), GY (Yellow–Green), G (Green), and P (Purple), with GY (Yellow–Green) being the most prevalent. The tones are primarily medium chroma and dark clear, as depicted in Figure 30b.

Lastly, the environmental colors of Camões Square are combined into a unified chromaticity chart, including hues of R (Red), YR (Yellow–Red), Y (Yellow), G (Green), GY (Yellow–Green), BG (Blue–Green), PB (Blue–Purple), P (Purple), and N (Achromatic), as illustrated in Figure 30c. GY (Yellow–Green) has the largest proportion at 60.3%, followed by YR (Yellow–Red), Y (Yellow), P (Purple), R (Red), N (Achromatic), G (Green), and PB (Blue–Purple), with BG (Blue–Green) being the smallest at 1.6%, as illustrated in Figure 30d. The overall tone exhibits high chroma at 60.3%, predominantly featuring bright, dark clear, and stable colors, followed by medium stable, light clear, white, and light stable tones, as detailed in Figure 30e.

Finally, by integrating the collected colors and removing duplicates, a color spectrum of the environmental colors at Camões Square was compiled, as specifically illustrated in Figure 31.

4.1.3. Classification and Characterization of the Macau Environmental Color Spectrum

Through the investigation and analysis of the environmental colors of various squares, a total of 505 colors were identified. After removing duplicate colors, a comprehensive collection of 291 colors for the Historic Center of Macau was compiled. These colors were categorized as follows: Y (Yellow) 46 colors, R (Red) 27 colors, YR (Yellow–Red) 38 colors, GY (Yellow–Green) 97 colors, G (Green) 26 colors, BG (Blue–Green) 17 colors, PB (Blue–Purple) 19 colors, B (Blue) 8 colors, RP (Red–Purple) 8 colors, P (Purple) 3 colors, and N (Achromatic) 2 colors. The final comprehensive spectrum of the environmental colors of the Historic Center of Macau, classified according to tone, is detailed in Figure 32.

The comprehensive environmental color spectrum revealed the following patterns:

(1)

R (Red): The majority of hues were high-chroma colors, followed by medium-chroma dark clear and light clear colors, with the least being low-chroma dark stable colors.

(2)

YR (Yellow–Red): Predominantly high-chroma colors, followed by medium-chroma dark clear, low-chroma dark stable, medium stable, and finally, medium-chroma light clear colors.

(3)

Y (Yellow): Mainly high-chroma colors, followed by medium-chroma light clear and dark clear colors, with the least being low-chroma dark stable, medium stable, and light stable colors.

(4)

GY (Yellow–Green): Primarily high-chroma colors, followed by medium-chroma dark clear, low-chroma dark stable, medium stable, and lastly, medium-chroma light clear colors.

(5)

G (Green): Mostly high-chroma colors, followed by medium-chroma light clear and dark clear colors, with the least being low-chroma light stable colors.

(6)

BG (Blue–Green): Mainly high-chroma colors, followed by medium-chroma dark clear and light clear colors.

• B (Blue): Predominantly high-chroma colors, followed by medium-chroma dark clear colors, and then low-chroma medium stable colors.

(7)

PB (Blue–Purple): Mostly high-chroma colors, followed by low-chroma medium stable, medium-chroma light clear, medium-chroma dark clear, and low-chroma dark stable colors.

(8)

P (Purple) and RP (Red–Purple): All hues are high-chroma colors.

(9)

N (Achromatic): Equally divided between white and medium grey.

Overall, it can be observed that the environmental colors of the Historic Center of Macau showed a preference for bright tones, with high-chroma colors accounting for 188 out of 291 colors, which is 64.6% of the total, as shown in Figure 33a. This was particularly evident in the high-chroma colors of GY (Yellow–Green), R (Red), YR (Yellow–Red), Y (Yellow), and G (Green), which were proportionally represented in the overall color spectrum, as shown in Figure 33b. Medium-chroma colors accounted for 58 colors (19.9%), low-chroma colors for 43 colors (14.8%), and achromatic colors for 2 colors (0.7%).

Therefore, it can be seen that the environmental colors in the Historic Center of Macau are rich and diverse. However, having a comprehensive color spectrum alone is not sufficient—it is more important to identify the most representative colors from this spectrum. The criteria for selecting representative colors can vary, but in this study, the principle for extracting representative environmental colors was to reflect the cultural connotations of Macau. This mainly included the following: the primary colors of historic district buildings, the prominent and frequently appearing colors of public facilities, the most frequently occurring colors in the landscape, and the significant and frequently appearing colors in cultural aspects. For landscape colors, due to their large number and the similarity among many of them, representative colors were chosen based on Munsell values, selecting one from neighboring colors. The proportion of tones in the extracted characteristic colors was similar to the overall proportions. Ultimately, 60 representative colors of the environmental colors in the Historic Center of Macau were selected, as illustrated in Figure 34.

5. Discussion and Implications

5.1. Problems Existing in Environmental Colors in the Historic Center of Macau

(1)

Lack of a Unified Management Mechanism

Field investigations and interviews revealed that different engineering companies are responsible for maintaining various buildings in the historic district. For example, the contractor for the restoration of St. Augustine’s Church is Pak Ka Construction Engineering, while the contractor for the roof and exterior wall restoration of Guia Lighthouse and Chapel of Our Lady of the Snow is Hong Dong Construction Engineering Co., Ltd. (a company registered in Macau, China)

These companies do not follow a unified set of rules or regulations, leading to inconsistent standards in construction processes and outcomes. Authenticity is a crucial principle in the protection of world historical and cultural heritage, defined by the intrinsic unity between the form of cultural heritage and its cultural value. Respecting the original characteristics of buildings is fundamental to maintaining authenticity. In the periodic maintenance of building colors, the use of different paint brands and color standards by various contractors results in subjective color applications that make it difficult to preserve the original appearance. Human eyes cannot accurately judge color harmony, and the mixing of paint can produce deviations under different conditions. To better protect the architectural colors in the Historic Center of Macau, a standardized color management mechanism is essential.

(2)

Lack of Overall Unity and Cohesion in Colors across Regions

Color unity from a macro visual aesthetics perspective is crucial. Although regional environments contain many color elements, achieving an orderly and hierarchical distribution of colors enhances the overall sense of the urban environment and highlights the city’s charm. Spillmann’s 1994 Kirchsteigfeld color scheme implemented his planning philosophy, using colors not only for individual facades but also for the continuity, integrity, and diversity of regional spaces and facades [12], emphasizing the logical relationship of the architectural environment [13]. Planning colors from a spatial perspective integrates color design with urban spaces, showcasing spatial configurations through color nodes, color axes, and hierarchical structures [35]. The lack of overall unity in Macau’s historic district colors can be attributed to the geographical distribution of the 8 squares and 22 buildings across different areas, making it challenging to achieve a cohesive effect without professional planning.

The relationship between colors primarily involves the degree of harmony between them. Different combinations of colors can produce various visual and psychological effects. The contrasts between colors, adjacent colors, and similar colors each create distinct perceptions. Therefore, in creating the color scheme of a spatial environment, it is essential to investigate and analyze both the primary and secondary environment colors. This enables reasonable control of the regional colors; otherwise, unregulated use of colors can easily result in a city or area lacking unique charm. As Kevin Lynch emphasized, carefully planned physical environments and people’s sensory experiences of a place add new dimensions to the current dialogue [36].

(3)

Insufficient Prominent Colors (Individual Colors and Characteristic Colors)

Prominent colors are those that attract attention and can hold a person’s gaze for an extended period. Yoshida Shingo’s research confirmed that colors indeed have attention-grabbing properties [37]. Visitors’ attention is often drawn to buildings, making it necessary to examine the aesthetic style, form, theme, and direction of buildings [38]. The form and position of colors play a key role in balancing the relationship between the city’s foreground and background, enhancing the city’s visual order and image [8]. Minah G’s “Color as Metaphor in Architectural Design” states that the hierarchical status of parts is shown by the perceptual weight of colors juxtaposed to one another by contrasts in hue, value, and chroma [39]. Generally, chroma is most closely related to attention-grabbing properties. Environmental color planning should emphasize the control of chroma.

In the overall environment of the Historic Center of Macau, low-chroma natural landscape colors dominate, as is common in most urban environments. Without enough high-chroma colors, it is difficult to leave a lasting impression. Therefore, some high-chroma colors in the spatial environment help enhance visual appeal.

5.2. Strategies for Protecting and Planning the Environmental Colors in the Historic Center of Macau

(1)

Establishing a Unified Management Mechanism

To better protect the environmental colors of the historic district, administrative authorities should formulate regulations adapted to environmental colors based on the characteristics of the Historic Center of Macau and relevant laws. In specific environmental color maintenance processes, designated agencies, materials, and color codes should be specified to control Macau’s environmental colors institutionally.

(2)

Color Control for Buffer Zones and Surrounding Areas (Color Grouping and Segmentation)

While overall unity in urban environmental color planning is important, excessive uniformity can appear monotonous and lack vitality. Harmonious unity in urban environmental colors should be complemented by more individualized colors to enrich the overall environment’s rhythm. Yoshida Shingo refers to this concept as color grouping and segmentation, which involves the unity of colors, shapes, proximity, opposing elements of similarity and proximity, and the continuity and variation of landscapes, ultimately seeking a unique residential landscape. The environmental colors of the Historic Center of Macau require holistic consideration, focusing on the core, buffer, and surrounding areas. Protecting the inherent colors of the core area and reasonably controlling the colors of buffer zones and surrounding areas, while integrating spatial aesthetics and functionality, ensures the best visual presentation of the area. This approach aligns with the objectives of the 2020 Macau Urban Master Plan draft, which emphasizes “characteristic commercial areas” and “landscape dimensions” to promote a unified city style through the regulation of the visual environment. The effectiveness of this strategy has also been demonstrated in previous urban color plan implementations. For example, Turin is renowned for its high-quality public spaces and harmonious colors, creating a unified image that respects the history of each building [40]. Tehran’s color plan was implemented in the 1990s with the primary goal of restoring color consistency, particularly in the historic center of the city [8].

(3)

Effective Identification and Control of Prominent Colors

Although the overall environment of the Historic Center of Macau presents bright tones, accounting for 64.6%, these are largely due to abundant landscape plants. Color combinations should emphasize focal points and layers that enhance the dynamics of the space, making urban spaces more meaningful and attractive, while also providing designers with greater creative freedom [35]. Therefore, effective identification and control of prominent colors in environmental color planning are necessary to leave a lasting impression on residents and tourists, enhancing the city’s distinctiveness and sense of place.

5.3. Theoretical and Practical Implications of the Environmental Color System in the Historic Center of Macau

From the theoretical perspective, the construction of the color system for the Historic Center of Macau expands research in the field of urban color studies in Macau, particularly by organizing and summarizing the color information of the material elements in each square of the historic district. Each square, as the physical carrier where colors manifest, presents unique characteristics. For instance, Lilau Square, a place where the Portuguese once lived, carries the cultural and historical memory of the Sino-Portuguese community. Barra Square, home to a Chinese temple, showcases traditional Chinese folk culture through its colorful lanterns, while the wave-patterned Portuguese cobblestone pavement reflects a distinctive maritime cultural heritage. These features also bear witness to the interaction and exchange between Chinese and Western cultures in Macau.

From the practical perspective, the Government of Macau Special Administrative Region’s approved Urban Master Plan of Macau (2020–2040) indicates that there is no comprehensive plan for the city’s color design and planning. However, as a UNESCO World Heritage site, the Historic Center of Macau holds significant practical value in constructing a distinctive local image. In light of this, the color system developed in this study can serve as a reference for color planning and management in the Historic Center of Macau. This could include the management and control of colors in various squares and the application of color guidance in cultural and creative designs.

Additionally, the study revealed an uneven development of colors across the squares in the Historic Center. Specifically, cultural colors are only presented in 3 of the 8 squares: Barra Square with 11 colors, the Company of Jesus Square with 6 colors, and Senado Square with 24 colors. These areas are primarily associated with Chinese and Western religious activities, as well as commercial and cultural events. This underscores the fact that colors, as they relate to specific physical spaces, carry cultural value. Moreover, the physical space can be enhanced by the colors of cultural elements, thereby strengthening the atmosphere and shaping the local identity.

6. Conclusions

The Historic Center of Macau, as a UNESCO World Cultural Heritage site, benefits from the construction of a color system that can be integrated into urban planning and design applications. More importantly, it provides a color system that helps to better preserve the unique characteristics of the historic district. Through the extraction and analysis of architectural colors and the environmental colors of the squares within the Historic Center of Macau, this study compiled a comprehensive color spectrum of the buildings, individual color spectrums for each square, and an overall color spectrum for the entire historic district, thereby constructing a color system for the Historic Center of Macau. Based on the distribution of color information, 60 representative colors were identified. It was found that the color composition and expression of the 8 squares in the Historic Center of Macau differ significantly, with Senado Square having the most colors, a total of 97, which is closely related to its extensive commercial and cultural exchanges. The most common material carriers of color are landscape and architectural colors, with GY (Yellow–Green) being the most frequent. Furthermore, the origin of each square’s colors is linked to the area’s function, population, and cultural memory. For example, Barra Square, home to the A-Ma Temple, reflects the characteristics of traditional Chinese religious and folk culture, Lilau Square presents scenes of Portuguese life in the past, and the Company of Jesus Square bears witness to the spread of Western Catholic culture in the East. These color systems of the squares provide insight into the formation of local culture. In conclusion, by conducting field surveys and recording color information, it is possible to construct an urban color system that can be applied to urban planning and design, while also interpreting cultural meanings through color.

6.1. Limitations

The advantage of the color system construction method used in this study lies in its detailed presentation of the environmental colors of urban physical spaces, as well as its systematic and refined categorization of urban environmental colors, including architectural colors, landscape colors, public facility colors, and cultural colors. This classification facilitates detailed analysis and allows for the management of specific spatial colors. From the investigation perspective, the method employed in this study emphasizes the influence of the geographical environment on color and places a strong emphasis on field investigations. This approach helps obtain more accurate color information, which is beneficial for subsequent color analysis and categorization.

However, the method used in this study also has its inevitable limitations. First, the selection of color samples lacks a more scientific approach, and when dealing with complex and diverse material color carriers, it is easy to overlook or miss some color information. Second, the process of color extraction is prone to interference. Traditional methods of color extraction using color swatches can result in inaccurate subjective judgments, and there can be significant discrepancies between the results obtained with color sensors and those of color swatches. These limitations may affect the objectivity and accuracy of the final color system construction.

Moreover, it is known that colors do not remain unchanged over time—they change under the influence of environmental conditions. This study is grounded in the period from modern to contemporary times when Portugal governed Macau, focusing on the color appearances that have persisted until today. By documenting and analyzing the current color characteristics of historical architecture, this research not only helps preserve the cultural heritage in its contemporary context but also offers inspiration and insights for urban landscape design in the current social environment. Furthermore, the summarization and classification of existing environmental colors provide a valuable reference for the continuation of future urban identity, especially as the Macao Special Administrative Region government has enacted urban planning laws with a particular focus on the preservation and study of architecture with artistic value in the Historic Center of Macau. Therefore, this research holds significant value as a preliminary study.

Finally, the colors of historical architecture are often correlated with the era in which they were constructed. Some architecture may not retain their original colors, which presents an aspect worth further investigation and verification in future studies.

6.2. Future Research

Future research could consider the following aspects. First, since color is often influenced by objective factors, such as temperature, humidity, and lighting, it is important to focus on how to ensure the accuracy of extracted colors within a reasonable range. Second, color analysis methods could be diversified, including the integrated use of eye-tracking and EEG technologies, to provide more possibilities for interpreting the research results. Third, the physical space of urban color is significantly affected by objective factors, such as time and climate, leading to different color presentations. For example, the colors of a city during the day differ from those at night, and the colors in summer differ from those in winter. How to conduct a more comprehensive construction and analysis of urban environmental colors is a topic worth further exploration.