Flexoki is an inky color scheme for prose and code that I created for my personal site. It's now open source. Flexoki is designed for reading and writing on digital screens. It is inspired by analog printing inks and warm shades of paper. The name Flexoki comes from flexography — a common printing process for paper and cardboard. I spent many years working with dyes and inks particularly for my companies Inkodye and Lumi. I also have a fascination with digital paper. I wanted to bring the comfort of analog color to emissive digital screens. One challenge is that ink on paper is a subtractive process whereas LCD and OLED screens use additive color. Replicating the effect of mixing pigments digitally is difficult. Mixing blue and yellow paint creates green, whereas digital color mixing results in a brownish hue. Watercolors retain their saturation when you dilute them, whereas reducing the opacity of digital colors makes them look desaturated. Another challenge with digital color is human perception across color spaces. Ethan Schoonover’s color scheme Solarized (2011) was an important inspiration for Flexoki. His emphasis on CIELAB lightness relationships helped me understand how to find colors that appear cohesive. I found that choosing colors with perfect perceptual consistency can be at odds with the distinctiveness of colors in practical applications like syntax highlighting. If you adhere too closely to evenness in perceptual lightness you can end up with a palette that looks washed out and difficult to parse. Solving for all of these problems is how I arrived at Flexoki. I wish it could have been more science than art, but it wasn’t. Some day, I hope to arrive at a more reliable way to generate digital color palettes that respect the constraints I laid out. In the meantime, I hope you find this iteration of Flexoki useful.