I have a few thousand rectangular images of various sizes. I want them all to have a longer height than a width. I want to do this by rotating all images whose height is shorter than their width 90 degrees. How do I do this with imagemagick?
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1 Answer
You can write a simple function like below, to getting the width &height of the image then check if w>h then rotate it.
rotate() {
(( $(identify -format '%w > %h' "$1") )) && convert "$1" -rotate 90 "rotated_$1";
}
Call it like rotate image.png.
Another approach which is suggested and presented by user414777 using exif tool, that is doing the rotation based on the EXIF Orientation tags:
exif -co rotated_"$1" --ifd=0 --tag=0x0112 --set-value=6 "$1"
Switches explanations:
TagID TagName Writable Group Values/Notes
0x0112 Orientation int16u IFD0 1 = Horizontal (normal)
2 = Mirror horizontal
3 = Rotate 180
4 = Mirror vertical
5 = Mirror horizontal and rotate 270 CW
6 = Rotate 90 CW
7 = Mirror horizontal and rotate 90 CW
8 = Rotate 270 CW
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With jpeg files, just changing their exif orientation tag may be enough, which would be order of magnitude faster than physically rotating the image. Eg.
exif -co new.jpg --ifd=0 --tag=0x0112 --set-value=6 old.jpgOct 4, 2020 at 4:28 -
And changing the
IFS, creating an array, is a bit of overkill. With bash/ksh/zsh, you can do justun_landscape(){ (( $(identify -format '%w > %h' "$1") )) && convert "$1" -rotate 90 "rotated_$1"; }. This, of course, just in your answer, assuming they don't already have an exif orientation tag, in which case the width/height will have no relationship to the way in which they're displayed ;-) Oct 4, 2020 at 4:41 -
good suggestion and golfed version, I will update in my answer later if you don't mind. thanks– αғsнιηOct 4, 2020 at 4:55