Preserve image's modification time with mogrify/imagemagick

Question

I have a huge collection of family photos which I don't really need full resolution of. I want to use mogrify but I tried it on a sample set of images and it seems that it sets modification time of files to current time. Is there any way to preserve modification/create time of original image (for both EXIF data and linux's native file modification times which you can view using stat)?

Answer 1

You could always do it with a bit of scripting:

exiftool  -q -r -ext jpg -if '
    $ImageWidth > 1000 ||
    $ImageHeight > 1000 and
      !print "$Directory/$Filename\0"' . |
  xargs -r0 sh -c '
    for file do
      mv -i "$file" "$file.back" &&
        convert -resize "1000x1000>" "$file.back" "$file" &&
        touch -r "$file.back" "$file"
    done' sh

Here resizing the images so they fit into a bounding box of 1000x1000.

• exiftool is used to find the images that need resizing
• convert resizes them (doesn't touch the exif info)
• touch -r restores the original timestamp from the backup file

Answer 2

You can use ImageMagick mogrify to down-res (resize smaller) any files larger than 800x800 to fit within 800x800 and preserve their timestamps like this:

magick mogrify -define preserve-timestamp=true -resize '800x800>' *.jpg

If you want to test first without overwriting originals, but instead writing the resized files to a new directory called RESIZED, you can do:

mkdir RESIZED
magick mogrify -path RESIZED -define preserve-timestamp=true -resize '800x800>' *.jpg

Answer 3

I'm not sure about ImageMagick, but GraphicsMagick supports this natively.

$ ls -lh family_photo.jpg 
-rw-r--r-- 1 justin justin 901K Sep  9  2007 family_photo.jpg
$ gm mogrify -preserve-timestamp -rotate -90 family_photo.jpg 
$ ls -lh family_photo.jpg 
-rw-r--r-- 1 justin justin 681K Sep  9  2007 family_photo.jpg