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#!/bin/sh # # pamstretch-gen - a shell script which acts a little like a general # form of pamstretch, by scaling up with pamstretch then scaling # down with pnmscale. # # it also copes with N<1, but then it just uses pnmscale. :-) # # by Russell Marks, 1999. # Contributed to the public domain. if [ "$1" = "" ]; then echo 'usage: pamstretch-gen N [pnmfile]' exit 1 fi tempfile=$(mktemp -t pnmig.XXXXXXXXXX) || exit 1 #219019 if ! cat $2 >$tempfile 2>/dev/null; then echo 'pamstretch-gen: error reading file' 1>&2 exit 1 fi # we use the width as indication of how much to scale; width and # height are being scaled equally, so this should be ok. width=`pnmfile $tempfile 2>/dev/null|cut -d " " -f 3` if [ "$width" = "" ]; then echo 'pamstretch-gen: not a PNM file' 1>&2 exit 1 fi # should really use dc for maths, but awk is less painful :-) target_width=`awk 'BEGIN{printf("%d",'0.5+"$width"*"$1"')}'` # work out how far we have to scale it up with pnmstretch so that the # new width is >= the target width. int_scale=`awk ' BEGIN { int_scale=1;int_width='"$width"' while(int_width<'"$target_width"') { int_scale++ int_width+='"$width"' } print int_scale }'` if [ "$int_scale" -eq 1 ]; then pnmscale "$1" $tempfile else pamstretch "$int_scale" $tempfile | pnmscale -xsi "$target_width" fi rm -f $tempfile;