Comments on: CLI tricks: Creating image thumbnails

By: michuk

michuk — Fri, 11 May 2007 08:53:31 +0000

New article about ImageMagick with a lot more info: Enchanting Pictures with ImageMagick

By: Josu Lazkano

Josu Lazkano — Wed, 21 Feb 2007 08:58:53 +0000

how can I resize a lot of images inside a folder and that folder is near a lot of folder in other folder.

I don’t know if you understand me, something like this:

foder1
└>folder11
└>picture111
└>picture112
└>…
└>folder12
└>picture121
└>picture122
└>…
└>…

thanks

By: warpman

warpman — Mon, 06 Nov 2006 23:01:53 +0000

If you think it’s time for practical use call on to my Warpman’s http://WWW. I wrote three scripts: two to make screenshots and one to convert the pictures. The text describing the scripts is supplemented with a dozen or so screenshots. Have a nice reading and of course give ‘em a try!.
http://warpman.kv.net.pl/art/art_1037_txt_00.html
Regards.

By: Fredrik Rambris

Fredrik Rambris — Fri, 03 Nov 2006 14:40:42 +0000

A thing I did before creating my own thumbnailer was to use jpeglibs own scaler, which is very much faster than loading the whole image, scaling it down and then compressing it again.

djpeg -scale 1/8 $file | cjpeg -outfile thumb_$file

Or if you want it to be an exact size but not one that is perfectly dividable with the original size you first scale it to approximatly that size with djpeg and then use pnmscale to do the final bit. It is faster than just using pnmscale or convert for that matter.

djpeg -scale 1/8 $file | pnmscale -xysize 64 64 | cjpeg -outfile thumb_$file

By: cultrocker

cultrocker — Mon, 30 Oct 2006 14:52:46 +0000

Don’t forget the -thumbnail option of convert. It is used to do exactly this. It changes the size of the image to the value specified and strips the unwanted meta infomation off of the jpeg files.

convert infile.jpg -thumbnail 240×180! outfile.jpg

When processing many large files use the -size hint at the begining of options list. This speeds up conversion because convert only reads the file until enough of the image data is available to produce the lower resolution image. Try this.

convert -size 240×180 infile.jpg -thumbnail 240×180! outfile.jpg

This can will run much faster since the complete input file is not read. From the docs;

“use this option to choose a particular resolution layer of a JBIG or JPEG image (e.g. -size 1024×768)”

By: michuk

michuk — Mon, 30 Oct 2006 11:54:58 +0000

Thanks memals, I updated the article to include mogrify as well. I never use it though, since it overwrites the original file(s).

By: memals

memals — Mon, 30 Oct 2006 11:42:34 +0000

mogrify can do most of the simple convert commands and will operate on more than one file
mogrify -resize 200 *.jpg
if you have convert you will also have mogrify