How can I batch-correct white balance across many JPEGs shot under changing light?

Question

I have a large set of JPEG images of the same subject taken over several hours, so the color balance varies as the light changed. I want the images to end up with a more uniform white balance across the batch, while keeping each photo’s own exposure/brightness.

I’ve tried ImageMagick scripts and darktable, but the scripts were either too crude or too slow, and darktable just copied the same white-balance adjustment from one image to every file instead of recalculating per image.

Is there a practical way to batch-adjust JPEGs so each image gets its own automatic color correction, rather than applying one identical white-balance setting to all of them?

user37649 · Answer

If you find that hitting the "auto" button in the GIMP levels dialog generally does the thing you're looking for, you can batch that as described here.

Specifically, you would put this script:

(define (batch-auto-levels pattern)
(let* ((filelist (cadr (file-glob pattern 1))))
  (while (not (null? filelist))
         (let* ((filename (car filelist))
                (image (car (gimp-file-load RUN-NONINTERACTIVE
                                            filename filename)))
                (drawable (car (gimp-image-get-active-layer image))))
           (gimp-levels-stretch drawable)
           (gimp-file-save RUN-NONINTERACTIVE
                           image drawable filename filename)
           (gimp-image-delete image))
         (set! filelist (cdr filelist)))))

into the GIMP scripts directory (~/.gimp-x.x/scripts/ or %appdata%\GIMP\x.x\scripts on Windows) named 'batch-auto-levels.scm' and then run

gimp -ifd -b '(batch-auto-levels "*.jpg")' -b '(gimp-quit 0)'

within the directory containing the images. Note that this will overwrite the images - copy them to a test directory and work on that until you know the results are what you want. Also make sure that your metadata is intact (GIMP is pretty good about this these days). You can set the JPEG quality you want to use as the default in the GIMP JPEG export dialog, then quit GIMP before running the batch script.

How can I batch-correct white balance across many JPEGs shot under changing light?

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