ImageMagick®, version 6.3.1, is a software suite to create, edit, and compose bitmap images. It can read, convert and write images in a variety of formats (about 100) including DPX, GIF, JPEG, JPEG-2000, PDF, PhotoCD, PNG, Postscript, SVG, and TIFF. Use ImageMagick to translate, flip, mirror, rotate, scale, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bézier curves.

Official site : www.imagemagick.org, exemples : Examples of ImageMagick Usage.

memory

montage pierre-1.jpg pierre-2.jpg pierre-3.jpg
-geometry 200x200 -mode Concatenate -tile 1x index.jpg

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convert all jpg images :
for img in *.jpg
do
convert -sample 25%x25% $­­­­­­img ptt-$­­­­­­img
done
or
convert '*.jpg[120x120]' thumbnail%03d.png

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convertir toutes les images en jpg des sous-répertoires :
for img in $­­­(find . -iname '*.jpg'); do convert -sample 25%x25% $­­­img $­­­img-ptt.jpg ; done