I've been wanting to play with the Gimp::Fu modules and recently a perfect example came to me. I had a pile of PNG files which I needed to set the resolution (the dots per inch) of. I searched high and low for a program to do this but I couldn't find one. I could have written one in C using the PNG library but that seemed to be the only option (I couldn't find any useful Perl modules to help).

However I noticed the GIMP could set the resolution of PNGs so I wrote the following script. You can put it in your plugins directory and use it as part of the GIMP or you can use it as a command line program. You'll want to run the GIMP and start the Perl Server on Xtns=>Perl=>Server. Call it as :-

set-image-dpi.pl -dpi dpi -input /path/to/input_file -o /path/to/output_file.

I thought I share this with you since I haven't seen any GIMP Perl scripts on PerlMonks and a simple example like this might get the ball rolling!

#!/usr/bin/perl -w

use strict;
use Gimp ":auto";
use Gimp::Fu;

sub set_image_dpi
{
    my ($dpi, $input) = @_;

    # Load the file
    my $img = gimp_file_load($input, $input);

    # Set the resolution
    $img->set_resolution($dpi, $dpi);

    # Return the image
    return $img;
}

register
    "set_image_dpi",            # name
    "Set Image DPI",            # small description
    "Sets the dots per inch of an image", # help text
    "Nick Craig-Wood",          # Author name
    "Nick Craig-Wood",          # Copyright
    "2001-08-01",               # Date
    "<Toolbox>/Xtns/Perl-Fu/Set Image DPI",   # menu path
    "*",                       # Image types
    [
     [PF_FLOAT, "dpi",   "New DPI of image", 72],
     [PF_FILE,  "input", "Input File Name", ""],
    ],
    \&set_image_dpi;

exit main();
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