How to rotate a set of pictures from the command line?

I have a large set of JPEG pictures all with the same resolution. It would take too long to open each one inside the graphical interface of imagemagic or gimp.

How do I achieve each picture being rotated and saved as the same filename?

Answers:

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Method 1

You can use the convert command:

convert input.jpg -rotate <angle in degrees> out.jpg

To rotate 90 degrees clockwise:

convert input.jpg -rotate 90 out.jpg

To save the file with the same name:

convert file.jpg -rotate 90 file.jpg

To rotate all files:

for photo in *.jpg ; do convert $photo -rotate 90 $photo ; done

Alternatively, you can also use the mogrify command line tools (the best tool) recommended by @don-crissti:

mogrify -rotate 90 *.jpg

Method 2

For JPEG images and right-angle rotations, use jpegtran or exiftran, as they can rotate the images losslessly.

for f in *.jpg ; do 
    jpegtran -rotate 180 "$f" > "${f%.jpg}-rotated.jpg"
done

Or to rotate in-place:

for f in *.jpg ; do
    jpegtran -rotate 180 -outfile "$f" "$f"
done

exiftran also has the -a flag to automatically rotate the image based on what the EXIF orientation tag says.

Method 3

Note that the two other answers may provide different results depending on the EXIF Orientation : it seems that convert rotates with regards to the EXIF Orientation, while jpegtran just ignores the EXIF Orientation.

This observation led me to figure I actually needed to discard the EXIF Orientation, so I just used exiftool to discard EXIF data without further data loss (that’s also what does jpegtran when no -rotate option is given, it seems) :

exiftool -all= -o outfile.jpg infile.jpg

I could have just removed the EXIF Orientation with

exiftool -Orientation= -o outfile.jpg infile.jpg

or modified it with

exiftool -n -Orientation=1 -o outfile.jpg infile.jpg

(for this later case you will need to read the FAQ to understand option -n, needed for exiftool to translate the -Orientation value, and the EXIF tags table).

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0