I have 4 layers (A, B, C, D) which I wish to blend by the following formula (A xor B) plus (C xor D). Is it possible to accomplish this in Photoshop? I am a newbie and found that layer can only control it's blending with all underlying ones.


Maybe. Sort of.

The maths for blending modes probably doesn't fit exactly what you're after. Difference is the same as XOR, and I think Screen the closest you'll get to addition.

Screen Blending Mode

Difference Blending Mode

You should be able to set up the compositing you're after by setting a group blending mode.

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If you're after specific and precise values as a result, you may be better served by using something else (or writing your own little application in a high level language).

  • Is Difference not exactly the same as XOR? – e100 Oct 22 '12 at 13:57
  • Yeah, I think so. But I don't think screen is the same as pure addition of the values? I'll edit my response. – Marc Edwards Oct 22 '12 at 14:47
  • @e100 Difference and xor are only the same when both values are the same (eg. 100 - 100 = 0 = 100 xor 100). "Screen" is the same as multiply, but using darkness-values instead of lightness-values (so the end-result is lighter than the originals) – BlueRaja - Danny Pflughoeft Apr 27 '18 at 15:55

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