4.3.1. Materials

The visual artwork exploration evaluation was performed after the multi-sensory color code effectiveness evaluation. The evaluation consisted of two visual artwork color content exploration tasks. Two different methods were used for the exploration tasks. One of them consisted in exploring a tactile graphic version of Van Gogh's Starry Night shown in Figure 2a. This tactile graphic was designed to highlight the contours of the features of the artwork and uses a series of different tactile color patterns to express the simplified color contents. A legend with the tactile color patterns and the corresponding name of the color written in Braille was also available for the participants to review the tactile pattern-color pairs. The second method involved the use of the sensory substitution device for visual art color content exploration described in Section 3.4. This prototype makes use of the multi-sensory color code proposed in this work. The prototype was inside the usability laboratory where the other evaluations took place but located in a semi-isolated exhibition area set up as a small art gallery. The prototype has a touch interactive 2.5D surface that also depicts Van Gogh's Starry Night, as shown in Figure 2b. To prevent bias and inconsistency between the exploration methods, both provide feedback with the same color representations at similar regions. For example, the moon's color is represented

by a yellow-saturated (color composed of yellow hue and saturated dimension). Thus, the tactile pattern in the tactile graphics method corresponds to the yellow-saturated pattern. Similarly, in the sensory substitution device prototype, the audio feedback is Vivaldi's Four Seasons spring melody executed with a trumpet and trombone. In addition, the olfactory feedback is the scent of coffee. Together, audio and scent, also represent the yellow-saturated color. We assigned the following colors to the following features: the tree and mountains are green-dark, the wind and church blue-light, and the shine from the moon and haze above the mountains are blue-light.
