(01-29-2024, 06:30 PM)Ofnuts Wrote: AFAIK for each color channel individually it stretches the histogram so that the 2% levels with the lowest value becomes 0 and the 2% levels with the highest value become 255 (in other words, it automatically restores the black and white points in each color channel).Still trying to digest your most recent post but this response makes me think you are suggesting that I'd need to work on each of the R/G/B channels separately. I've always used the Value mode because I simply do NOT know what I'd be trying to accomplish by working on each channel separately. With that, said, I did give it a try in this case. Not sure how to figure out the 2% point but by separately moving the white and black points to their respective ends of the histogram for each channel I end up with result that is fairly close to what resulted from using Auto Input Levels. Actually the colors look to be about the same but the contrast NOT quite as high. I think I have a basic understanding about how to alter contrast using Tone Curves but NOT Levels. Is that even possible?
Might this mean that it is time for me to learn more about how to use the Levels Tool to manipulate the individual R/G/B channels? If so I'd love to find some documentation that explains particulars for different objectives that might be possible to achieve. I'm afraid the GIMP User Manual is NOT too hlep fl in this respect.
(01-29-2024, 06:58 PM)rich2005 Wrote:Thank you. I hadn't thought of using the Histogram Dock but that does appear to address my desire.Quote:....
Note: When the "Auto Input Levels" button is selected the image is changed quite dramatically in this case but nothing gets changed/updated within the "Adjust Color Levels" window. ...
If you bring up the histogram dock you do get a result showing when 'auto' is applied.
For an auto filter it is worth experimenting with the gmic plugin. There is a Colors -> Auto with couple of sliders and and some color space options and you do not get the 'comb-ing' as with the Gimp levels tool. This a before / after
I do have GMIC installed but lack experience actually using it. It is worth a try but I should point out that my reason for posting this topic is NOT that I'm dissatisfied with the result from Auto Input Levels. It is rather that the result is so remarkably good that I'd like to become more knowledgeable about what the tool is actually doing and hopefully make better use of it going forward.
(01-29-2024, 06:07 PM)ajax Wrote: ...I meant "GIMP 2.10.36".
These examples are derived from using GIMP 2.20.36 on Windows.
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