Batch Autocrop png Images in Gimp

 July 10, 2020      Stardate: 73989.1     Tagged as: Gimp

This article is to document the solution I found for batch auto-cropping a bunch of images within Gimp. Keep in mind that this runs the “Crop to Content” command within the Image menu, so if you can’t achieve what you want within the program than this isn’t going to give you different results.

To start, credit where credit is due. I didn’t want to learn how to write Gimp scripts so I found one from a Swede named Greg Hildström here, thanks Greg!

batch-autocrop.scm

  (define (batch-autocrop 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))))
                  
             (plug-in-autocrop RUN-NONINTERACTIVE
                                   image drawable)
                                   
             (gimp-file-save RUN-NONINTERACTIVE
                             image drawable filename filename)
             (gimp-image-delete image))
           (set! filelist (cdr filelist)))))

1. Copy the batch-autocrop.scm into the scripts folder

Where do Gimp scripts and plugin live? It’s easy to find out. Open Gimp and within the top menu bar select Edit\Preferences\Folders, expand Folders out and Select “Scripts”. It is recommended to put your personal scripts into your configuration folder as circled in red below.

2. Within a terminal change into the directory of images you want to crop and run the script

gimp -i -b '(batch-autocrop "*.PNG")' -b '(gimp-quit 0)'

If you are interested in what you just did continue reading.

• gimp is the command, you can run gimp -h to view the help page
• The flag -i means run without a user interface
• -b means run a batch command

Look up at the first line of the .scm script and you will see the definition of the batch command = “batch-autocrop pattern”. batch-autocrop is the command name and pattern is the input pattern of files you want to operate on. I don’t know why you need to wrap the batch command in both quotes and paranthesis, it seems to me that either one would be enough to differentiate the input, but regardless… the first batch command is gimp -i -b '(batch-autocrop “*.PNG”)' because I want to operate on everything in the current folder that ends with “.PNG”. For my particular configuration, capitalization was important; e.g. “.png” vs “.PNG” made a difference.

Lastly we need to close out the session because we don’t have an interface. This is another batch command -b '(gimp-quit 0)' meaning quite Gimp now.

And there you have it!