First I’ll comment on your post, then I’ll answer your question.
As a prelude to understanding and using Painter more, I’m trying to sort out some of the color mixing strategies the software offers.
To me, “mixing” refers to what happens to colors when they combine. I distinguish this from “blending” (which has a separate post) – blending is “how to push the pixels around”
In Painter, mixing, blending, smearing, blurring, and smudging are all “pushing pixels around” to give the illusion of a new color. The result is that “mixing occurs in the mind of the viewer”, to one degree or another. If you zoom in close, you’ll see that pixels have been moved around to mix them and present the illusion of a different/new color when the image is viewed at 100% zoom. (See your Category 1 below.)
Using your definition of “mixing” ( combine ) the only ways I can think of off hand are to use Layer Composite Methods or to paint lowered Opacity brushstrokes that cross over existing different colors. This is not really mixing, since nothing is stirred up, or moved. The pixels remain unmoved and only the way the colors are seen has changed to give the illusion of combined colors to form a new color.
Here’s an initial list broken into categories as I see them.
Can you think of any categories I’ve missed, or examples to add to my existing categories?
Category 1: OPTICAL MIXING
No attempt to blend occurs on the canvas. Paint strokes form small lines or dots. The color mixing occurs in the mind of the viewer.
It would hardly seem likely the artist would do this without some degree of attempt to blend/mix colors. The artist attempts to give the illusion of blended/mixed colors when painting this way or, without the conscious and deliberate attempt, intuitively makes the attempt since the result, if the small lines or dots (brush dabs) are small enough and the image is viewed at 100% zoom, this is the resulting illusion, blending/mixing of colors to form the illusion of different/new color. Traditional pointillism, I guess, might be a good example or, in Painter, painting with a brush variant set to scatter small closely spaced dabs of varying colors in each brushstroke, or by painting with a scattering dab brush variant with single different colors painted layer by layer to form the illusion of different/new color.
Mixing Category 2: OPACITY MIXING
Easing off on a pressure-sensitive pen lets you ease off on opacity. The resulting color in a 50% blend would be the same color you’d get midway along a two color ramp. In this world, halfway between pure blue and pure yellow is gray.
An easier way to test this might be to choose the Pens’ Scratchboard tool, set Opacity to 50%, then paint first a blue stroke, then a yellow stroke crossing over the blue stroke. Then paint first a yellow stroke, then a blue stroke crossing over the yellow stroke. Where the first two strokes cross, you’ll get a greyish yellow. Where the second two strokes cross, you’ll get a greyish blue.
Try doing this in Painter, and I think you’ll see that you get quite different color results using these two methods:
Create a Two-point Gradient using blue (R:0 G:0 B:255) and yellow (R:255 G:255 B:0). Then make a rectangular selection on an otherwise transparent Layer above a blank white Canvas. Use Ctrl/Command+F to Fill, Using: Gradient and set the Fill Opacity to 50%. Turn on Rulers and with the unit of Ruler measure set to Inches, drag a Guide to 1 inch, and using the Dropper tool, click on the Gradient at the 1 inch point (where the Guide line is). You should get a light grey.
Now, using the same blue and yellow, mix them in the Mixer palette and try to pick the closest to grey you can find in the mix. You’ll see that it’s very difficult, if not impossible, to get a “grey” that’s not visibly more yellow or more blue.
Using a third method, I was able to come closer to the Two-point Gradient method result. That is, to choose the Artist’s Oils’ Wet Oily Blender variant and mix the same blue and yellow on a blank white Canvas. It’s still not the more pure grey using the Gradient method, but closer than using the Mixer palette method.
Mixing Category 3: RGB COLOR MIXING
Represents colors with only 3 spectral samples: RGB. Treats color mixing like a “multiply.” In this world, pure yellow and pure blue mix to black.
Practically speaking, how would you do this in Painter? If you mean to do it in the Color Info palette, by adjusting the sliders, I can’t see how that’s possible since we can only specify one color at a time there.
Mixing Category 4: MULTISPECTRAL COLOR MIXING
Internally converts 3D color to a higher dimensional color space with 9 or even 12 spectral samples. Down-converts back to 3 samples for display purposes. In this world, colors that appear pure blue and pure yellow mix to green because the software gives pure-looking blue and yellow some hidden green qualities in the higher dimensions, and the green from each pigment survives the mix. ** possibly exists in the Artists Oils. Possibly does not exist in Painter. I haven’t explored too much here yet.
Since Painter only works in RGB color, mixing pure blue with pure yellow does not result in green. Instead we need to use yellow and cyan to get green.
In Painter pigment doesn’t exist, only light displaying a variety of colored pixels.
Now to answer your question
First, I think you may be making this much more complicated than it needs to be. Unless we just enjoy knowing the science behind how Painter color works, we don’t need to know or understand it. Painter makes it easy once we know the various ways we can pick, specify, and mix color. It’s even easy if all we use is the Colors palette.
The methods that come to mind for color mixing/blending/smearing/smudging/blurring to create the illusion of new color by mixing up existing differently colored pixels are:
Mix in the Mixer palette
Mix on the Canvas using brush variants that have blending and smearing characteristics (including those not found in the Blenders brush category, and including using the Artist’s Oils variants with the Dirty box checked).
Two-point Gradient method described above
Two methods to combine colors and produce the illusion of other colors while not actually mixing up (stirring up, or moving) existing pixels:
Using Layer Composite Methods to combine colors on two or more Layers and/or the Canvas.
Paint with brushstrokes set to lowered Opacity over existing different color to produce the illusion of new/other color.
While these methods are neither mixing in the sense of stirring up (or moving existing multiple colored pixels to result in the illusion of different/new color) nor combining two colors one above the other to result in the illusion of other/new color, they are more loosely a way of “mixing” colors by using two or more colors within a single brushstroke. In both cases, the multiple colors are visible when the image is viewed at 100% zoom unless the brushstroke is too small to see the multiple colors (or even to paint multiple colors in a single brushstroke):
Painting with a brush variant set to scatter dabs of varying color paint, either on the Canvas, on a Layer, or on multiple Layers.
Painting with a brush variant (using one of several Dab Types and Stroke Types) set to use Color Variability.