How can I color only the non-white colors in a layer?

Question

I often have a situation where I get a foreground image with a background color like this:

I want to display this without the white background, so I set the blend mode to Darken:

But now I want to color all the black pixels blue, and I can't figure out how to do this. If I set a Color Overlay style, it overlays the entire rectangle with blue.

(I've tried just masking out the white, but it's very hard to get a clean mask because of the aliasing at the boundary between light and dark.)

So, is there a way to work with just the pixels that are visible given the layer blend mode?

Answer 1

• First set the image layer to Multiply rather than Darken (Based on the background layer Darken may not work for the blue since some values in the background may be close to the value of blue you choose. Multiply will definitely work.)
• create a new layer above the image
• Fill the new layer with your blue
• Set the blue layer Blend Mode to Lighten
• Option/Alt-click between the blue layer and the image layer on the Layers Panel to create a layer clipping mask. This causes the blue layer to only alter the image layer it is "clipped" to.

This should result in only the black being colored blue.