Resizing image files

See also

http://www.commandlinefu.com/commands/tagged/1066/resize

mogrify command

Resize all JPEGs in a directory

This command requires the imagemagick libraries and will resize all files with the .JPG extension to a width of 800 pixels and will keep the same proportions as the original image. 

mogrify -resize 800 *.JPG

google picasa use case 

cp *.JPG web
cd web
mogrify -resize 800 *.JPG
date; google picasa -d "2011-10-27" -n "Minou et Ali à Annecy le 27 octobre 2011" -t "Annecy, 27 octobre 2011" create "Annecy, 27 octobre 2011" *.JPG; date

Script bash : how to shrink a list of jpg files with the ‘convert’ command 

 1#!/usr/bin/env bash
 2# The image size_max will be 800
 3
 4size_max=800
 5mkdir ${size_max}
 6
 7for filename in *.jpg; do
 8    input=${filename}
 9    name=${filename%.*}
10    suffixe=${filename##*.}
11    output="800/"${name}_${size_max}.${suffixe}
12    echo "Input: ${input}"
13    echo "File Name: ${name}"
14    echo "File Extension: ${suffixe}"
15    echo "output: ${output}"
16
17    convert ${input} -resize ${size_max} ${output}
18done