My understanding is that the Hue blend mode is supposed to use the hue from the top layer, and the saturation and brightness from the bottom layer.
I placed a red in the bottom layer. RGB = (255, 0, 0), HSB = (0°, 100%, 100%)
I placed a blue in the top layer. RGB = (0, 255, 255), HSB = (180°, 100%, 100%)
The resulting color was as follows: RGB = (1, 108, 108), HSB = (180°, 99%, 42%)
As you can see, the saturation dropped slightly and the brightness dropped a lot. That goes against everything I've read about this blend mode.
- Why is this happening?
- How can I predict the effect on the resulting color's saturation and brightness?
I've found that the resulting color's saturation and brightness will drop by various amounts depending on the hue of the top layer, or the hue of the bottom layer. Unfortunately, I can't identify a pattern, it seems fairly sporadic.
Also, changing the saturation or brightness of the top layer's color does not affect the resulting color's RGB or HSB values. Changing the saturation or brightness of the bottom layer does alter the resulting color's saturation and/or brightness, but not the hue.
I'm testing this in Photoshop (Version 24.0.0). I'm checking the colors with the color picker and Photoshop's Info panel. I'm not sure if it matters, but under Image > Mode, I have RGB Color and 8 Bits/Channel both checked (I think those are default settings).