RiverMan Media

RGB Color Mixing

First let’s practice by creating a color wheel. Create a black layer, and lock its transparency by clicking the transparency lock icon in the layers palette. Then set the background color to black. Set the brush tool to Linear Dodge (Add) mode and the eraser tool to Normal mode.

Using only pure red, green, and blue, practice creating colors by sketching a color wheel. Red and green make yellow, red and blue make magenta, and blue and green make cyan. All three colors combine to make white. You can create a grayscale ramp by applying equal parts of each color in a gradation.

Try making something like this:

Try to get a good sense of how the three primary colors interact before you move on.

RGB Color Mixing from a photo

Once you’ve got the feel of creating colors by mixing red, green, and blue light, you can try something much more challenging: replicating a photograph.

First, choose a reference photo to work from. I chose this photo of some peppers because it had some bright, bold, colors, but also some subtle muted tones. It doesn’t matter too much what photo you choose—anything will be a challenge!

Put the photo on its own layer. Then make a new layer over it and trace the photo with a fine, white line. (Tracing is optional, but this is a color exercise, not a drawing exercise, so we don’t want to focus too much on scale and proportion.) In between the trace and the photo, add a layer of black, and you should get something like this:

Make sure your brush tool is still on Linear Dodge (Add) mode and set to work painting on the black layer. You are using only pure red, green, and blue. I started by blocking in the main colors like this:

After I had the main shapes defined, I started layering colors to create secondary colors. For example, I used red and a little green to make orange. I also started blocking in the background.

I’m continuing to layer colors a little bit at a time. I added some highlights by mixing all three colors, and continued building up the background tones. If an area ever gets too bright, I use the black eraser to push it back down.

As the colors approach a greater degree of accuracy, most areas of the painting now have some amount of each color component, since there are very few pure colors in photographic images.

Finally, I used the blend tool to solidify the forms and remove some of the anomalies produced by layering colors:

By this point you should have a good feel of how red, green, and blue light combine to create different colors. Now let’s do the same exercise in reverse!