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Glenn Mingham
Glenn Mingham
Participating Frequently
April 9, 2018
Answered

Brush Blend Modes Question

  • April 9, 2018
  • 1 reply
  • 821 views

Could somebody please help me understand something I've long wondered about...

Why, when we paint on non transparent areas of a layer with a Brush Blend Mode other than Normal, the effect is as expected (Hue, Sat, etc change accordingly)  but... when brushed over unfilled, transparent areas, it is as if we are painting with Normal mode?

I have never understood this: why, if we are painting only to change e.g. the Hue of what's there would we want blank areas to not remain blank?

I hope this screenshot illustrates what I mean...

Dropbox - Adobe Forum - Brush Blend modes.png

This topic has been closed for replies.
Correct answer davescm

A blend (brush or layer) can only happen if there is something to blend with. If there are no pixels to blend with then the result will just be the brush (or layer) content.

Dave

1 reply

davescm
Community Expert
davescmCommunity ExpertCorrect answer
Community Expert
April 9, 2018

A blend (brush or layer) can only happen if there is something to blend with. If there are no pixels to blend with then the result will just be the brush (or layer) content.

Dave

Glenn Mingham
Glenn MinghamAuthor
Participating Frequently
April 10, 2018

Thank you Dave...

But I hoped my illustration made clear that I do (not expertly) understand what happens...that, as you say: If there are no pixels to blend with then the result will just be the brush (...) content.

My question is "Why?"

Does not logic suggest that if a brush is set not to cover but to blend, and there are no pixels to be blended, then there would/should be no result at all?

Because isn't that the point: to Blend is not - by definition - to Cover?

A brushstroke of blue on a Layer with Blend mode set to Hue does not cause empty areas of the Layer beneath to appear as blue.

So why should a Brush with Blend Mode of Hue cover empty areas with Blue?

I have never myself come across a situation where that is what I'd choose to happen. Perhaps you, or somebody, could suggest where or how it could be of any practical use?

JohanElzenga
Community Expert
JohanElzengaCommunity Expert
Community Expert
April 10, 2018

A brush paints pixels, so if you paint over an empty area, it fills that empty area with pixels too. The blend mode of the brush determines how existing pixels are 'mixed' with the pixels painted by the brush. If there are no existing pixels, then nothing gets mixed and so the result is what you painted.

A brushstroke of blue on a layer with Blend mode set to Hue does not cause empty areas of the Layer beneath to appear as blue, because the area beneath is still empty. That's the difference between painting with the brush set to a certain blend mode, and painting on a layer set to the same blend mode.

-- Johan W. Elzenga
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