How is the componentMax CIBlendKernel different from lighten or lighterColor?

Question

CIBlendKernel offers a componentMax blending mode that “creates an image using the maximum values of two images”.

How is it different from either the lighten or lighterColor blending modes, which do the same thing? Can componentMax achieve a result which these two can’t?

Similarly, can componentMin ever achieve a result different from that of either darken or darkerColor?

Answer 1

My guess is that componentMax really takes the maximum value of each RGB color component and combines them into the result color. So for instance 100% red and 100% blue would result in a violet color.

In contrast the lighten/darken blend modes are probably based on the lightness or luminance value associated with the color. In this case the resulting color is the lighter/darker one of the two, not a combination. So, taking the example from above, the result would be red because it's perceived lighter than blue.

I guess in many cases they seem the same because colors with higher component values tend to be lighter.