Shell script for adjusting image size

Question

Is there a way to adjust all image sizes in a directory? If I set the max size to 800x600 it will make larger ones smaller and leave smaller ones at their original size.

Has anyone got a solution for that? Any help would really be appreciated!

Answer 1

image magick package needs to be installed: mogrify -resize 320x240 *.jpg where 320 = width, 240 = height

or you can just leave width parameter: mogrify -resize 320 *.jpg and rest will be taken care of.

Answer 2

Various packages exist for command line or script driven manipulation of image files.

I'd suggest looking at netpbm, or ImageMagick. Personally I prefer the former as it's far simpler to use.

Answer 3

for img in *.png; do
    convert "$img" "800x600>" $(basename "$img" .png)_new.png
done

convert is from ImageMagick. ">" says it's only resized if larger. See here for its other options.