It’s always good to have another set of eyes to review your work, a lesson reinforced when Emily pointed out I had forgotten not everyone would know what 8-bit RGB332 color is. This is a rather critical part of using my color composite video out Arduino library, assembled with code from rossumur’s ESP_8_BIT project and Adafruit’s GFX library. I started with the easy part of amending my library README to talk about RGB332 color and list color codes for a few common colors to get people started, but I want to give them access to the rest of the color palette as well.
Which led to the next challenge: What’s the best way to present this color palette? There is a fairly fundamental part of this challenge: there are three dimensions to a RGB color value: Red, Green, and Blue. But a chart on a web page only has two dimensions. Dictating that diagrams illustrating color spaces can only show a two-dimensional slice out of a three dimension volume.
For this challenge, being limited to just 256 colors became an advantage. It’s a small enough number that I could show all 256 colors by putting a few such slices side by side. The easiest one is to slice among the blue axis, since it only had two bits in RGB332 so there are only four slices of blue. Each slice of blue shows all combinations of the red and green channels. They had three bits each for 23 = 8 values, and combining them means 8 * 8 = 64 colors in each slice of blue. The header image for this post arranges the four blue slices side-by-side. This is a variant of my Arduino library example
RGB332_pulseB which changes the blue channel over time instead of laying them out side by side.
But even though this was a complete representation of the palette, Emily and I were unsatisfied with this layout. Too many similar colors were separated by this layout. Intuitively it feels like there should be a potential arrangement for RGB332 colors that would allow similar colors to always be near each other. It wouldn’t apply in the general case, but we only have 256 colors to worry about, and that might work to our advantage again. Emily dived into Photoshop because she’s familiar with that tool, and designed some very creative approaches to the idea. I’m not as good with Photoshop, so I dived into what I’m familiar with: writing code.