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Recursive JPEGTRAN: Rotate your images with lossless results

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 PostPosted: Thu Jul 23, 2009 10:57 pm   

Joined: Thu Jul 23, 2009 10:38 pm
Posts: 1
For those of you who are unaware of what jpegtran is, I suggest you press the link and read the Wikipedia article.

To install jpegtran, I used the following on Debian / Ubuntu:
# apt-get install libjpeg-progs

Remember, in order to execute the shell script, the file permissions should be altered:
# chmod a+x

The following is a code I have been writing to try to recursively rotate an entire directory of portrait images. Here are the details:

    Files to be rotated are moved in a directory ROTATE
    All final files are written to the parent directory of ROTATE
    File names are in the format DSC#####.JPG (no .jpg or .JPEG)
    File names are only 12 characters long

Here's the code. I've named it

picls=$(ls -1 /home/kp/Pictures/ROTATE)
while [ $numero -lt  257 ]; do
   picname=$(echo ${picls:$numero:12})
   `jpegtran -rotate 270 -outfile /home/kp/Pictures/$picname /home/kp/Pictures/ROTATE/$picname`
   numero=$(expr $numero + 13)

Now, unfortunately, I keep getting the following error from bash:
Empty input file
./ 9: Bad substitution

If anybody could provide insight on why bash is angry, then this shell script might be of some use!

 PostPosted: Fri Jul 24, 2009 12:35 am   

Joined: Mon Nov 17, 2008 7:25 am
Posts: 221
First of all, that solution seems like a tricky one. But all roads lead to rome.

This is probably how I would've done it anyway.

for i in $in_path/*; do
   out_file=$(basename $i)
   jpegtran -rotate 270 -outfile $out_path/$out_file $i

usage: ./ /path/to/original/files /path/to/rotated/files

the first 4 lines shouldn't be that hard to decode.
Next up is the basename feature, it just convert an absolute path to just a filename.
And then your convert line

Best regards
Fredrik Eriksson

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