Result unchanged from input image.

[gimp-plugins-justice]

Result unchanged from input image.

[prokoudine]

Turns out, you can use Deskew for this use case as well, if you crop close enough first :)

[prokoudine]

Well, two things :)

1. Deskew was designed to handle scanned documents, not photos.

2. You will have a lot more luck with GIMP 2.10.6 where you can easily fix rotation with the Measure tool. Just drag a line across the border of your image, then click 'Straighten' button in tool's options dock.

[pr3sidentspence]

Ahhh, thanks,

I discovered deskew because it was supported by another Gimp plugin (script, to be precise) DivideScannedImages.

Yeah, we've done that in the past, but we're talking tens of thousands of images. I need automation. The good news is I think I've managed to get it working with ImageMagick scripts.

[jdl51]

pr3sidentspence,

Ahhh, thanks,

I discovered deskew because it was supported by another Gimp plugin (script, to be precise) DivideScannedImages.

Yeah, we've done that in the past, but we're talking tens of thousands of images. I need automation. The good news is I think I've managed to get it working with ImageMagick scripts.

How did you manage to get it working using ImageMagick scripts. I'm facing the same issue with deskew not working on GIMP 2.10 in linux. I'm trying to archive a bunch of scanned family photos and need to straighten thousands of photos after using "Adams divide scanned images" script.

[pr3sidentspence]

How did you manage to get it working using ImageMagick scripts.

Sorry I didn't see this sooner. See this PowerShell script: https://gist.github.com/pr3sidentspence/84af7b1eca2a0f1ae416dab2950c5b83 . Specifically, the function rotator. It expects to find an image in a subdirectory called "small" (created by the function makeSmalls). Doing gap detection and deskewing on giant images takes a long time, so I create smaller versions first, get the results from ImageMagick then apply those results to the full original. Occasionally, IM would give me results that couldn't be correct (in my case anyway) and I would throw out those results and not deskew that image.

function rotator {
Write-Host Determining if $_ needs straightening
$rotation = & magick small$_ -background $colour -deskew 20% -print %[deskew:angle]\n null:
if ($rotation -lt $rotThresh) {
& magick small$_ -background "$colour" -rotate $rotation small$_
& magick singles$_ -background "$colour" -rotate $rotation singles$_
Write-Host $rotation degrees of rotation applied
}
else {
Write-Host the $rotation value was over the rotation threshold of $rotThresh
}
}

[pr3sidentspence]

PS- It sounds like it's too late for you, but that script will allow one to scan a number of photos at once, and automatically separate, deskew, and crop (leaving some of the background showing) the photos. The only caveat is that there can only be a single column of photos on the scanner. I didn't code a hard limit on the number of photos there could be, but if they get small enough the math will stop working.