(10-27-2023, 06:05 AM)sallyanne Wrote: The only reason I can fathom that you scanned with such a high ppi is your images are quite small/large?
Anyways I don't think you can use the same adjustments as each picture is different.
I have medium-format negatives. Scanning on an Epson V600 at 3200 consumes too much time, even though I have only a couple thousand negatives. I want 3200 on some of them so I can enlarge to 16" x 16" at 400 DPI. (I know 300 DPI is the convention for printing, but I am picky.)
Since I would scan the same negative twice, the only difference being PPI, I'd expect the scans to differ only slightly. That is optimistic, since years can pass between the 600 and 3200 scans, but the difference in color adjustment ought to be manageable. My problem is that I am inept in adjusting the colors. I stumbled on a satisfactory adjustment for a particular 600-PPI negative, but I cannot reproduce what I did. Hence my hope that GIMP can remember what I did, and apply it again, to a different TIF file.
(10-27-2023, 08:16 AM)Ofnuts Wrote: You can do that with a CLUT (Color Lookup Table) which is a way to describe the mapping between input colors and output colors. Such a map should in theory be 16MPix, but you can in practice do with somewhat less (64 values per channel is fairly common).
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Thanks! That sounds formidable, but I might work up the courage to try it.
(10-27-2023, 08:22 AM)Ofnuts Wrote:Yep. That's what I wish to do. First, I don't want to go through the tedious manual steps of color adjustment for each negative. Second, I don't know what I am doing, so if my flailing lands on something I like, I need help to do it again.(10-27-2023, 06:05 AM)sallyanne Wrote: The only reason I can fathom that you scanned with such a high ppi is your images are quite small/large?
Anyways I don't think you can use the same adjustments as each picture is different.
Negatives are quite small image (24x26mm so roughly 1" by 1.5"). So at 3200PPI this the equivalent of a 16Mpx image from a camera.
Then each negative film has its own color characteristic, so it makes sens to process images from the same negative the same way to compensate for it on all images.
It would be wonderful if GIMP could capture a history of substantive actions for later play-back. The Undo History is tantalizing. One imagines saving it, and running it forward on a different image file. (A "substantive action" would be something that makes a change.)