In “Subtleties of Color” author says what a powerful tool color is in visualization, how it clarifies data and helps people to understand complicated patterns. I find this reading interesting because it brought out a topic I already unconsciously have in my brain but simply haven’t realized it on the conscious level. There is a picture in the book representing bar of lightness, hue and saturation. I see these elements many times in Photoshop when I change colors of some objects. However, I did not know that it is a converted graph from computer’s colors perception to human colors perception. I even remember having difficulties creating color I wanted in P5.js. It was because computer and I had different perception of color. Computers perceive colors as linear and symmetrical, while humans perceive them as non-linear. Because we see colors in a non-linear way, the rainbow palette in chapter 2 accentuates two lines of bright cyan and yellow area, and a wide range of green.
Then, author mentioned why lightness is the most important form the visualization. With gradient changes, sequential data is able to show change easily. Apart from the sequential data, there are two data sets: divergent data and categorical data. Divergent data is perfect for representing two different sets of data and showing the middle of data, e.g. stock market fluctuations. It also shows the middle ground which doesn’t have any association with two different sets of data. Meanwhile, categorical data does not tend to show correlation of data, but different categories of data. To represent categorical data, it is important to use different color range to not confuse the reader. Other than that, author mentions good advice in terms of using color data visualization.
It was a great minder for me. For example, he said to use color to separate data from non-data. This is something I knew before, yet I didn’t think about it consciously. Since computer’s perception is different from human, it is important to humanize data visualization, so that the readers would be able to understand it clearly.