Group Draw Isolated issue?

[kopias]

Hello. I would like to ask why I get different result when enabling "draw isolated" in this simplified example where I only have this one group. This seams wired for me so maybe its a bug or something to do with raw layer, but I'm not an expert so figure out I ask here.

[Hoogo]

I guess you forgot the attachment?

[kopias]

sorry it was due to too large filesize - edited firs post

[Hoogo]

Interesting, I see a slight change in brightness when I switch between encapsulated and normal.
No idea...
Ctrl+Shift+C/Ctrl+V always gives the encapsulated result, same does reducing to background.
Removing the color profile and turning off color management made no difference.

[Martin Huber]

If you make the document 16-bit per channel, the difference disappears. It also disappears, if you reduce the image layer to 8 bit.
If you turn on/off antialiasing, you will see the difference, too.

So it seems, that isolated groups don't dither 16 bit images, and the difference in brightness comes from the fact, that the adjustment layer has a slightly different effect on the dithered pixels compared to the undithered ones.

Martin

[kopias]

Here I illustrate this issue with practical example and a workaround.

On both screenshots "Draw Isolated" is enabled for a group.

In first example we see 2 RAW layers ( from *cr2 canon) and adjustment layer with settings to develop them. I limit the adjustment layer to just those layers by using group with draw isolated enabled, but as you can see there some loss of quality (wich is because of some 16bit 8bit conversion... I think).

On second screenshot I workaround this issue by making adjustment layer a child of one RAW layer (which limits it to this layer) and making a virtual copy of this adjustment layer and make it child of second RAW layer (red arrow).

Just from the curiosity, if some developer could explain whats happening? It's a known limitation or something else?

P.S. I`m sorry if this is not clear, English is not my native languge.

[kopias]

If you make the document 16-bit per channel, the difference disappears. It also disappears, if you reduce the image layer to 8 bit.
If you turn on/off antialiasing, you will see the difference, too.

So it seems, that isolated groups don't dither 16 bit images, and the difference in brightness comes from the fact, that the adjustment layer has a slightly different effect on the dithered pixels compared to the undithered ones.

Martin

THX Changing from Picture Mode to Document mode and setting it to 16Bit fixes this issue

[Martin Huber]

THX Changing from Picture Mode to Document mode and setting it to 16Bit fixes this issue

You shouldn't have to switch to Document Mode.
In Picture Mode the background layer controls the bit depth of the document. If the background layer has 16 bits per channel, the document will have 16 bits per channel, too. If the background layer has only 8 bits per channel, the document will have, too.

Martin