*1.4. Proposed System*

We have investigated tactile actuation for co-centric protruding points at different angular positions in our preliminary study [32]. The swell-paper relief pattern utilized dots on the boundary of a circle and a square, with uniform angular spacing between tactile dots at 45°and 90°, respectively. The focus group experiments revealed the discernment ability for angular tactile patterns, and the learnability of colors assigned to those patterns. Based on the outcomes of the preliminary study, we propose an integrated color pattern scheme for angular tactile color translation. The color gamu<sup>t</sup> codes primary colors (red, blue, and yellow) and secondary colors (orange, green, and purple) from Goethe's color triangle. These six basic color hues are further coded into three levels of chroma and value (light, saturated, dark) as the color tone for each of the color hues. In addition, six levels of gray-scale colors ranging from white to black are included as achromatic colors from Munsell's color system. These integrated colors are coded into an angular tactile color pictogram, wherein the orientation of the tactile dot determines the color information. Our proposed system also integrates the TCP with an analog wearable watch for PVI. The ColorWatch interface consists of two disks in distinct shapes of round and square, each with a tactile dot at their boundary, the angular position of which indicates the color hue and color tones, respectively. In contrast to related works on TCPs, the spatial tactile system automatically interprets reference color. The reference color acquired through a color sensor from artwork or real-life objects actively alters the angular position of rotatable disks, developing the tactile pattern corresponding to reference color for the appreciation of PVIs. The cross-modular association of tactile color perception considers tactile actuation, design aspects of color significance, and color placement. The proposed analog watch design with TCP integration is intuitively understandable, which makes it easily learnable for PVI. A prototype for the proposed interface has been developed and color identification tests have been performed. The results for identification and usability tests, work-load assessment, and qualitative feedback sugges<sup>t</sup> that the developed scheme can be helpful for PVIs in tactile color perception.
