Crops an image file to a specified size and offset, renames with same prefix as original. Requires ImageMagick.

crop_rename.sh

#!/bin/bash
#Crops an image file to a specified size and offset, 
#renames with same prefix as original. 
#REQUIRES ImageMagick.

Y1=$1
Y2=$2
X1=$3
X2=$4

MYDIR="corner_keys"
EXT="png"

if [[ -z $Y1 ]]; then Y1=88 ; fi
if [[ -z $Y2 ]]; then Y2=212 ; fi
if [[ -z $X1 ]]; then X1=193 ; fi
if [[ -z $X2 ]]; then X2=497 ; fi


let KEYWIDTH=$X2-$X1
let KEYHEIGHT=$Y2-$Y1

PREFIXLENGTH=6

if [ ! -d ./${MYDIR} ]; then mkdir ./${MYDIR}; fi

# processes all pngs
if ls | grep png; then for p in *.png; do
    echo "Processing $p"
    prefixonly=${p:0:$PREFIXLENGTH}
    convert \( $p -crop ${KEYWIDTH}x${KEYHEIGHT}+${X1}+${Y1} +repage \) \
        ./${MYDIR}/${prefixonly}_cnrkey.png
done
fi