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Unable to copy alpha channel
#3
(08-23-2023, 06:35 AM)Ofnuts Wrote:
(08-23-2023, 06:09 AM)dscriven Wrote: I have a number of hi-res (600 dpi) images that contain transparency. I want to create a montage of these images but when I copy and paste the original images into the montage base image (which has a transparency channel) the alpha channel is not copied and the transparency is lost.

This not a Windows 10 or 11 issue - the same thing happens in Linux (Fedora 37) as well. Even more confusing is that using the sequence Edit->Paste as->New Image produces a perfect copy with the transparency intact, which would indicate that the image is not altered by the copying process, but something is happening during the paste process.

This is of some urgency as I need to publish this montage ASAP.

Is there a solution in GIMP - or do I need to look elsewhere?

Works for me...

Do you copy them as new layers? What is the image mode of the target image (full RGB, indexed?). If you chnage Gimp's background color to something recognizable (ie, not white or black), what do you see where the transparency is lost?

The target is full RGB and I've tried pasting them as layers, directly and it makes no difference - the RGB channels are fine and the alpha channel is not copied. I also use ctrl+H to merge the layers. You can see that the alpha is not copied by comparing the channels in the original and the copy. The only effect is that the image becomes paler as the colours are blended - there is a lot of blue green in the images.
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Messages In This Thread
Unable to copy alpha channel - by dscriven - 08-23-2023, 06:09 AM
RE: Unable to copy alpha channel - by Ofnuts - 08-23-2023, 06:35 AM
RE: Unable to copy alpha channel - by dscriven - 08-23-2023, 08:30 AM
RE: Unable to copy alpha channel - by rich2005 - 08-23-2023, 09:23 AM
RE: Unable to copy alpha channel - by dscriven - 08-23-2023, 08:01 PM
RE: Unable to copy alpha channel - by Ofnuts - 08-23-2023, 08:38 PM
RE: Unable to copy alpha channel - by dscriven - 08-24-2023, 06:27 AM

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