Guidelines for using color blending in data visualization

Visualization is a powerful way to convey data, showing po-tential for joining and interrelating data items. However, when dealing with large amounts of data, visually merg-ing different classes of information poses several challenges. Color, however, due to its effectiveness for labeling and cat-egorizing information, may be a solution to this shortcom-ing. Merging items with different colors may suggest mixing their original colors. This approach generates an immedi-ately perceivable way to represent merged items. It also keeps context through the association of the mixed color to its original colors. We studied to which extent color blending provides users with the means to understand the provenience of data items by conducting two user studies using CIE-LCh, CMYK and HSV blending to ascertain (i) to which extent people are able to, given a particular color, understand its provenience, and (ii) the color model in which to perform color blending so that users find it intuitive. Results showed colors which are more suitable for blending so that users un-derstand their provenience and indicated that the CIE-LCh model is more effective for representing color blending