GIMP Version: 2.8.10
Operating System: Linux
GIMP Experience: Beginner Level

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I open an image, create duplicate of the layer
put the top one on Overlay, then try changing the mode to Softlight to see the difference but there isn't any - at least not noticable by the human eye!!
I tried the same with another image - same thing!
Did the same with the same images in Photoshop and there is a clear difference between the two modes as you would expect.

If you read the footnote [5] on the Layer modes documentation: http://docs.gimp.org/2.8/en/gimp-concep ... modes.html you will see that there is a very long-standing bug: http://bugzilla.gnome.org/show_bug.cgi?id=162395 that means Overlay mode is using the wrong equation.

The developers are intending to offer some kind of solution in GIMP 2.10

Kevin

Oh thanks for the explanation I was flumuxed! and Gobsmacked!
The foot note doesn't say which versions have this bug. Is it just 2.8 versions?
If so I will try and find an earlier version and install that and remove 2.8 as I find Overlay mode very useful.

lol; yeah, the passed on a bug and never fixed (nor will they now).

As a side note, G'MIC offers many more layer blending options thin either GIMP or PS. It also does Overlay correctly.

The bug was reported in 2004 and the first comment says the formulas haven't changed since the code was added in 2002, so you are not going to find a working version.

Last time we had a discussion about this it involved G'MIC: viewtopic.php?f=28&t=6248&start=10 so that might be a way for you to get a real Overlay mode.

Alternatively, this thread from nearly 7 years ago: http://www.gimptalk.com/index.php?/topi ... oft-light/ suggests that swapping the position of the two layers and setting the top one to Hard light gives the correct effect.

Kevin

OK thanks again, I am just going to use Mypaint or Pinta - Open the, the layer- top layer Overlay then merge down -then use the result as a layer in Gimp.

Kevin,
I do not quite understand.
I read the posts on http://www.gimptalk.com/index.php?/topi ... oft-light/ and https://bugzilla.gnome.org/show_bug.cgi?id=162395

Basically they say:

"1 set layer in hard light mode ...but first invert their position"
or
"PS overlay mode= Gimp hard light mode but with top and bottom layer reversed "
or
"is actually identical to GIMP hard light mode with the top and and bottom
layers reversed."
or
B (Hard Light)
A (Normal)
then reverse
A (Hard Light)
B (Normal)

But if the top layer is a copy of the layer botton, reverse these layers would not make sense. I'd still be applying only hard mode light.

But if A=B ? (B being only one copy of A)

Ha Ha I got confused by it too - I'll wait for someone to write a script to do it LOL

the instructions on REVERT LAYERS and set Hardlight IS NOT REFERRED to identical layers.
Make a test with 2 DIFFERENT layers, and you will see the difference:



which is identical to:



but different from:

just to complete the example, look at the hardlight mode WITHOUT inverting the layers



This one is the regular Hardlight for putting a plasma over an image,
while by inverting the layers you should obtain (but I'm not expert on that) the effect of putting a plasma over an image in Softlight mode

Dinasset, Ok that was clear.

The question that remains is?

How to produce Overlay on identical layers with Gimp?

In G'MIC the result is identical to that technique of inverted layers.
Even in G'MIC what you get when you have identical layers is the Hard Light. (just like in Gimp)

It's been like that for years, I suppose the others said why by now. lol

I haven't thought through this, but perhaps it's possible to create a layer with a script, so that when that layer is set to overlay mode, it would actually work properly as an overlay.