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GreycLab / gmic

GREYC's Magic for Image Computing: A Full-Featured Open-Source Framework for Image Processing
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Can NOT Zoom Out when using GMIC Local Contrast #52

Open aaeneas opened 2 months ago

aaeneas commented 2 months ago

When using GIMP to edit photos taken with a digital camera the resolution is normally high enough that when you want to view the entire image (even on a relatively high resolution display device) Zoom ends up being set somewhere between 10% and 15%. However, when using the Details>Local Contrast filter within the GMIC Plugin for GIMP it changes to 100%, which ends up displaying a small fraction of the total image, and Zoom Out gets disabled. In that, the lowest Zoom setting allowed is 100%.

While I understand that zooming in on a particular part of an image is often desired when making Local Contrast adjustments, it seems to me that assessing the affect on the entire image is an important part of determining whether or NOT the ultimate result is positive (i.e., successful) and therefore should be applied. I doubt that this approach is peculiar to me. Therefore, being able to Zoom Out is important. Enough so that the very use of GMIC depends on being able to do so.

I first experienced this problem when using Version 3.3.6 of the GMIC Plugin with GIMP Version 2.10.38. Fortunately I run GIMP on Windows in portable fashion. This allows me to install new versions without altering existing versions. Therefore, I'm able to resume using older versions as desired. I tried quite a few combinations that failed similarly but did find an instance of GIMP Version 2.10.32 that was using Version 3.1.3 of the GMIC Plugin that works as desired/expected. In that, I can zoom out after applying Local Contrast. I think I'm stuck with it until this problem can be fixed.

dtschump commented 2 months ago

Please look at : https://discuss.pixls.us/t/gmic-plugin-zoom-problem This is actually an intended behavior, as certain filters cannot render an accurate preview when zoom factor of the preview window is modified.

aaeneas commented 2 months ago

So this is intended behavior but NOT up to and including Version 3.1.3. GMIC has been around for a long time. Has this always been a problem that was just recently discovered?

As previously mentioned I do have GMIC Version 3.1.3 running on GIMP 2.10.32 that does NOT exhibit this problem. With that said I realize that I can NOT say with any certainty that the preview is accurate but it does change and those changes appear to have taken effect within the GIMP preview after GMIC is closed which is NO longer the case when using the latest versions of GIMP and GMIC (more details below).

However, I've now also discovered that these better results only occur when running GIMP and GMIC on one of my computers. When I take the same installation to another computer I've experienced various errors that seem to have the affect of disabling the use of "Local Contrast" (i.e., the Local Contrast filter does NOT appear under "Detail" as a valid option to choose). Several screen shots that depict the kind of errors experienced follow: g_string_free_and_steal heif_deinit update223 gmic

I suspect that a possible reason for this difference may be that I've never used a newer version of GMIC than 3.1.3 on the computer where it functions correctly.

Another finding on the most up-to-date version running GIMP Version 2.10.38 and GMIC Version 3.3.6 is that there is NO change shown in the preview image when exercising the "Local Contrast" filter. Apparently, I did NOT notice this while wrestling with the Preview Zoom problem. This pretty much makes it (Local Contrast at minimum but I suspect other filters as well) completely useless.