If you work in any kind of design field, then there is a very good chance that accurately picking and viewing colors is an important part of your process. Choosing colors depends a great deal on the display medium. For example, colors show up differently in print then they do on computer monitors—even if those monitors are properly calibrated. The same is true for various kinds of RGB LEDs and their color differs from one model to the next and even from one specific LED to the next when manufacturing quality control is lax. As a “thank you” to the designers Guy Dupont has worked with, he built the Dial Toner hardware color picker.
There are many ways to define colors and some methods are better suited to some mediums than others. In the world of print media, CMYK (Cyan, Magenta, Yellow, Key) tends to be the preferred model. In digital photography, the HSV (Hue, Saturation, Value) model is more common. In general computing, the RGB (Red, Green, Blue) model is most popular. The RGB model defines a color according to its three color channels, each of which has a range of 0-255. With an 8-bit total of 256 values, one can represent each channel with a pair of hex digits. Those range from #000000 for black to #FFFFFF for white. Dupont’s Dial Toner contains six clicky dials to set the hex values, so users can dial-in any of the 16,777,216 possible RGB colors.
As the user adjusts the values of each hex digit, an RGB LED on the Dial Toner automatically changes color to match. That RGB LED sits underneath a mechanical key switch and the user can press that to send the current value to a computer connected via USB. That lets a designer pick a color based on what it looks like on a real-world RGB LED, and then easily copy the RGB hex code for use in software or firmware. The computer interface can convert that to CMYK or HSV if the user needs those values instead of RGB. This is very handy, since the way a color appears on a monitor is going to be different than it appears on an LED.
The six dials, RGB LED, and mechanical key switch sit on a compact PCB that Dupont designed for this project. Underneath is a Seeed Studio XIAO RP2040 development board, which handles the color-picking and the USB interface. Naysayers will point out that this RGB LED can’t accurately produce the full RGB color spectrum, but that’s the point. The whole idea here is to find colors that look good on such an LED, because that isn’t always obvious when selecting colors on a computer’s monitor.