This is one mode that I have never, ever used. I’m probably not the best person to post something on it, but since I’m covering all the other blend modes I couldn’t exactly skip it. So I went to Photoshop help, as it was extremely descriptive with Difference mode, and found…
Exclusion Mode: Creates an effect similar to but lower in contrast than the Difference mode. Blending with white inverts the base color values. Blending with black produces no change.
“Similar to but lower in contrast.” Yep, that’s the best it gets with the explanation for how it works.
I came up with an example graphic to show just how “similar” these two modes are. I have two blue rectangles, overlaid with two additional layers of white/purple/black gradients. One gradient is set to Exclusion mode while the other is set to Difference mode. The overlapping part is the “result” of the blends.
Stunning similarities, aren’t there? Sorry, did I just drip some sarcasm on your keyboard? From what I can tell, blending with pure white and black in Difference Mode or Exclusion Mode produces the same result — but the middle values are quite different.
Just to confuse us even more, I created another example graphic:
Again, pure white and pure black act the same as they would in Difference Mode by kind of “inverting” the color (subtracting the color values from white, which is 255-255-255). The middle values are kind of similar as well, with a slight tint related with the blending color.
So. Where does that leave us? Honestly, the only example of a practical application that I could fall back on was the same one as my last blog, using pure white and black shapes to create a “cutout” effect. While experimenting with Exclusion Mode did result in some interesting, weird, digital-image effects, there wasn’t anything that seemed especially useful to pass on.
I’m sorry if I disappointed you — this mode was a little too exclusive for me. So as always, I welcome you to post your own experiments or links to examples of cool uses of exclusion mode!