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Question

Difference Blend problem.

Forum|Forum|6 years ago
June 19, 2019
4 replies
1696 views

Hi.
I have no idea wether this specific problem has been adressed before or not. I did a quick search but couldn't find anything really relevant.

Here goes: when using a layer with blending mode set to difference in a multi layered document in order to change colours,
these colours are not interpreted correctly when saving or merging the document. (If necessary I can show an example.)
Did anyone ever encounter the same problem?
Did he or she find a solution/workaround?
Is it.... tatataaa... a bug?

I'd love to know, because it is very annoying.

Kind regards

Jean-Pierre van Rumste
Belgium

This topic has been closed for replies.

S

sylwesterł78733104

Participant

I encountered the same problem - Dirrefence blending works different in 8-bit and in 16/32-bit mode.

Difference is one of the 8 special belnding modes, which means it renders different result when adjusting Fill and Opacity.

And it seems Difference is treated as "special" for 8-bit mode, and as "normal" in 16/32 bit modes. I'm not sure it it is bug or a feature....

Myra Ferguson

Community Expert

Dave is right. If you go to Image > Mode, change it to 8 bits/channel, and then merge, then the reddish color stays.

davescm

Community Expert

This is not a bug*. It is just tbe way Photoshop works and always has worked since the introduction of 16 bit capability. I understand it was done to speed up redraw and in most images makes no visible difference. However with certain images the difference can be dramatic.

Given the faster processing available from modern GPUs it would be nice if the zoomed out versions were done in full 16 bit, however until then the advice is always zoom in and check your blending at 100%

Dave

Edit : See later post. Although there are normall differences seen in blending between 8 and 16 bit, there may also be a specific bug involved in the way opacity and fill interact in difference blend mode between 8bit and 16 bit)

Chuck Uebele

Community Expert

Dave, Even with your explanation, this seems odd. Why the dramatic shift with 16 bit? If using 8 bit, this doesn't happen, and you get the composite view of the zoomed out version of 16 bit. Seems like a bug that 16 bit and 8 bit do not blend the same.

JPvanRAuthor

Participating Frequently

Hi Dave.
If I figured this out right you should be able to find a PSD file here:
Adobe Creative Cloud

Hope that works.

davescm

Community Expert

Hi

To share from Create Cloud click on the three dots

Then on Share

Set "Allow download" then click "Copy Link"

Paste the link here

Dave

JPvanRAuthor

Participating Frequently

https://adobe.ly/2IXkNkc

davescm

Community Expert

No bug here with difference blend mode but :

1. Make sure you are viewing the blend at 100% zoom. At zoom levels less than 66.7%, 8 bit previews are used to draw the screen blend- not the full image data. That can lead to some differences when merging. So the accurate preview is always the 100% zoom..

2. Some blending is now done on the GPU and can lead to issues if the GPU driver is buggy. Try going to Preferences > Performance and check "Legacy Compositing". Then close and restart Photoshop.

Dave

JPvanRAuthor

Participating Frequently

I can look at whatever zoom percentage I want, the problem is consistent at each and every one of them and has nothing to do with viewing. The problem occurs when merging or saving. Then all of a sudden the color changes due tot difference blending mode being either misinterpreted or simply ignored. I'm not sure which one.
I use an NVidia GTX 970M with an Eizo monitor. Never had any problems.

davescm

Community Expert

If it is neither of the above then please post a link to an example file which shows the issue you describe. I'll try it here.

Dave

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