02-15-2020, 09:54 PM
A little more than a year ago I posted this topic regarding tif files created by GIMP.
I've now noticed something else about such files which I find strange. It seems possible that this could contribute to some compatibility issues discussed therein. However, compatibility is NOT the only issue.
It now looks to me like GIMP is adding an alpha channel NO matter what I do. For example, I can open a tif format file created by another program and according to GIMP there is no alpha channel. Then I do nothing but export that file from GIMP in tif format. When I subsequently open that file in GIMP it says there is an alpha channel. Furthermore, the newly created alpha channel does nothing. It appears to be completely opaque (i.e., complete white, no transparency). Obviously I don't know what is causing the compatibility problem but I do think I should be able to create a tif file without said alpha channel which would be a format more like what other image editors I'm using do.
Another problem I've noticed with tif files created by GIMP is that they are much larger than what other software would produce for the same image. The tif file created by GIMP is approximately 1/3 larger than it needs to be. The experiment mentioned above where I just opened (input) a tif file and exported it in tif format is that the file grew from 60MB to 80MB. Given that it went from 3 channels (RGB) to 4 (RGBa) that seems like this explains the phenomenom.
What I've been doing for some time now which is quite annoying is opening the files I produce with GIMP using some other editor (typically Rawtherapee), which fortunately is able to open them, and then exporting them again without doing any editing and the resulting file turns out to be about 75% the size of the GIMP produced input file.
It seems like GIMP should be able to omit the alpha channel. I'm hoping I just need someone to explain how that can be done.
I've now noticed something else about such files which I find strange. It seems possible that this could contribute to some compatibility issues discussed therein. However, compatibility is NOT the only issue.
It now looks to me like GIMP is adding an alpha channel NO matter what I do. For example, I can open a tif format file created by another program and according to GIMP there is no alpha channel. Then I do nothing but export that file from GIMP in tif format. When I subsequently open that file in GIMP it says there is an alpha channel. Furthermore, the newly created alpha channel does nothing. It appears to be completely opaque (i.e., complete white, no transparency). Obviously I don't know what is causing the compatibility problem but I do think I should be able to create a tif file without said alpha channel which would be a format more like what other image editors I'm using do.
Another problem I've noticed with tif files created by GIMP is that they are much larger than what other software would produce for the same image. The tif file created by GIMP is approximately 1/3 larger than it needs to be. The experiment mentioned above where I just opened (input) a tif file and exported it in tif format is that the file grew from 60MB to 80MB. Given that it went from 3 channels (RGB) to 4 (RGBa) that seems like this explains the phenomenom.
What I've been doing for some time now which is quite annoying is opening the files I produce with GIMP using some other editor (typically Rawtherapee), which fortunately is able to open them, and then exporting them again without doing any editing and the resulting file turns out to be about 75% the size of the GIMP produced input file.
It seems like GIMP should be able to omit the alpha channel. I'm hoping I just need someone to explain how that can be done.