Refine Masks with Paint Brush (Overlay mode)

[DrEvilking]

Hey all,

how can i use the paint brush in the overlay mode to refine my masks? In Photoshop i used the overlay mode and then i could brush over lets say bright areas and the dark areas wouldnt get affected and vice versa. But in Affinity when i use the overlay mode for my paint brush nothing actually changes.

Would be nice if you can help me out here!

With kind regards,

DrEvilking

[v_kyr]

See ...

• Edit selection as layer using Quick Mask mode

• APh Working with masks

[DrEvilking]

Well thanks for the links but that wasnt what i meant. Ill try to rephrase my question:

Lets pretend i copied the blue channel of an image to mask out the sky. Now there are different tonal values, its not just pure white or pure black. So what i would do in Photoshop is i would take the Paint brush and switch the painting mode to overlay (theres also darken, lighten, screen etc.). Now if i would have the black color on my brush and would go over a dark and bright part, it would only affect the darker parts and make them darker. Also i could use the white brush and make the brighter parts brighter, so i can have a better mask.

Now if i try this in Affinity Photo the overlay mode does absolutely nothing, it just paints over the mask like its the "normal" painting mode.

Why is that so and how can i make it work right?

[smadell]

I'm pretty sure I know exactly what you're after. I think the problem you're facing is that Photoshop (as I understand it) treats masks, and indeed all channels, as greyscale layers when they're being edited. So, the brushes, adjustments, etc. tend to work just as they would if you were editing a regular pixel layer. Affinity Photo, on the other hand, treats masks as they truly are – alpha channels, with no color whatsoever. Trying to edit them as if they are pixel layers just doesn't work. (Wish it would, but that's another story.)

The answer to do what you're after is a workaround. Instead of making a mask out of, say, the blue channel, start by making the blue channel into a Greyscale layer. This will create a greyscale pixel layer in the Layers stack, which you can edit like the pixel layer it is. Take your black or white brush, set the blend mode to Overlay, and have at it. Once you've got your purely black and white layer (which is, I assume, what you're after) choose Rasterize to Mask by right-clicking the layer in the Layers panel, or by choosing it from the Layer menu. Drag the mask that results into the proper layer.

[DrEvilking]

Thanks very much!