[Gimp-user] Gimp 2.10 autocrop equivalent

[rich404 <forums gimpusers com>]

> Dear Helpers
>
> I have recently updated to Gimp 2.10 (under Ubuntu 18.04). I use Gimp
> extensively for processing photos.  One very common problem is having
> the photo tilted by a few degrees.  It is easy to straighten it using
> the rotate tool or the new way via the measurement tool.  In Gimp 2.8
> it used to be very easy to crop off any excess using the autocrop
> tool.  However nothing I have tried works that way in Gimp 2.10.
>
> I created a small image to demonstrate what happens.  On the left is
> my "photo" a bit out of whack;). IN the middle is a screen shot of the
> image after rotation.  The third is what I would like, which autocrop
> under Gimp 2.8 would create.   In GImp 2.10, if I "crop to content"
> (under Image menu item) then I get an error message saying "cannot
> crop because the image is already cropped to content". Using "crop to
> selection" then the grey border inside the yellow dotted lines
> disappears which is what one would expect.  I would like the crop to
> be such that it crops off the outer section plus  all the transparent
> sections.
>
> I have searched for an answer but could not get the results as
> described in
> http://www.gimpusers.com/forums/gimp-user/20922-crop-to-selection-not-working
>
> Any help would be much appreciated:)
>
> Thanks
>
> Margaret

It is the alpha channel which interferes.

1. Using the Gimp 2.10 measure tool for straightening, recommend set "Clipping"
to clip.

2. Apply that and then consider the background colour. If it is white as your
example the skip the next. Photographs often have an off-white value .

3. If needed, colour-pick the background color and then Layer -> Transparency ->
Remove alpha channel. That should give a solid uniform background.

4. Apply zealous crop or crop to content.

A better way for the background colour might be using the
resynthesizer/heal-transparency plugins. (***don't use*** the registry-plugin
deb package for this, grab them separately) then remove alpha.

rich: www.gimp-forum.net

Attachments:
* http://www.gimpusers.com/system/attachments/1060/original/01-crop.jpg
* http://www.gimpusers.com/system/attachments/1061/original/02-crop.jpg

-- 
rich404 (via www.gimpusers.com/forums)