GIMP Version: 2.10.24
Operating System: Windows
GIMP Experience: Intermediate Level

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I really love the effect setting a layer to dodge can have, but I'm having trouble getting the look I want for some projects. If I dodge something with a solid fill, no problem. If I want to dodge something with any kind of transparency, it doesn't work like I want. Dodge seems to be 100% or 0%, with nothing in between. But I've seen PS tuts do dodge on a gradient transparency. [I even tried dodging a selection and applying a layer mask with a gradient for transparency, but it still gives a hard line between full color and no color.]

Is there a way around this? Maybe a custom plug in or script? I have G'MIC installed and found the "dodge and burn" there, but it's not for this. Thanks!

Dodge layer mode works as intended with transparency as well, no hard edges...
Screenshot

A question does your bottom layer has an alpha channel?
If you could post a screenshot with the layer's stack/dialog included, this would help us to find out what you're doing wrong.
Maybe you can upload an example ".xcf" (2 layers only should be enough) for us to test it, may be also link your photoshop tuto.

Last but not least, your GIMP Version is 2.10.24, may be upgrade it? the latest is 2.10.32, although I don't think it's a bug

Are you applying your mask before changing the layer mode? And I assume you know you need two layers for the layer mode to work

Pixlab:

The bottom layer does have an alpha channel.

I made a simplified example. Here's the layer stack:


Here's a top layer set to normal so you can see the blurred edges with partial transparency:



And here's that same layer set to dodge. There's no longer any transparency in the object's boundary--it's just a solid shape.



If I try to erase along the edge with a soft brush set to any opacity under 50%, it does not erase. If I erase with a brush set over 50% but under 100%, it erases 100%. Similarly, layer masking does not work as usual.

Last time I updated from .24 to .28, some of my legacy plugins I love stopped working, so I'm sticking with this version for now.


Sallyanne. I have two layers, and it doesn't seem to matter whether I apply the layer mask before or after changing the top layer's blending mode--as soon as it's dodge, it loses transparency.

Thanks!

Would help if you posted the link to the tutorial

Hello!

I have the same bug. If I choose 'legacy' dodge mode, the bug disappears.

GIMP Version: 2.10.30
Operating System: Linux

What is 'legacy' mode? I'm running 2.8 still, maybe that version doesn't have it?

You can get that effect when using a Gimp 2.8 .xcf file or maybe created an effect in Gimp 2.10 using an old script.

As a fix, one way is as cli345 explained and set the layer mode to legacy values. A better way for Gimp 2.10 is keep the layer default mode, and set the Blend Space to linear - right click in the layer, top of the menu.

30 second example: https://i.imgur.com/Nx6NTwZ.mp4

Thank you so much, cli345!

Changing to legacy blending mode worked, and I would never have thought of it. I kept trying 32-bit floating point precision, thinking it might be an issue like gradient banding, but that didn't work either.

I have no idea why this is happening since these are new files created in Gimp 2.10 instead of 8, but as long as there's a fix, I'll take it!

rich2005, I tried leaving it default and changing the blend space, but it didn't help. Your video was very good, though. I'm not sure why it didn't "blur" the edges on mine like it did in yours.

"Legacy" just means the older version of blend modes etcetera. The default now is 2.10 on... There is a little difference with some of the modes - I have not looked into it yet but you may if you choose to update to 2.10

OK, I think we ALL are affected

Same image, same dodge layer, but different background
example 1


Example 2


here is the xcf if you want to try

One of the circumstances for Blend Space.



Going back to the difference between Gimp 2.10 and 2.8
Gimp 2.10 does calculations in linear mode. When the blend is in gamma then you get those boundary effects. Typically seen using the Smudge tool. Nasty border effect. Which is why legacy modes are best avoided.



...but as with most Gimp it is up to the user to decide.
Edit: My guess is OP is using an old plugin/script such as the StarScape script for the basic background which renders in legacy mode.

Pixlab. I agree! The reason you don't notice it in your first example is because there's so much black in the bottom layer you're not seeing the hard edges of the dodge layer. Your second background has enough brightness that it shows.


Rich2005. Nope, sorry! The background is a stock background jpg, not something I created with an old script. But I had desat it and recolored it using a different dodge layer that I merged down, so maybe that did something to it.

I did try changing the blend space on another file that hadn't been manipulated, and it worked. So I'll keep your advice in mind and try your fix first.