Wrote this little bash script to go though a directory of PNG files and find the smallest width/height for a DOM element that fits any image in a set. The set of images is made up of a "close", "open" and "stroke" image sprites.

file-list.txt

t01-close.png
t01-open.png
t01-stroke.png
t02-close.png
t02-open.png
t02-stroke.png
t03-close.png
t03-open.png
t03-stroke.png
t04-close.png
t04-open.png
t04-stroke.png
t05-close.png
t05-open.png
t05-stroke.png
t06-close.png
t06-open.png
t06-stroke.png
t07-close.png
t07-open.png
t07-stroke.png
t08-close.png
t08-open.png
t08-stroke.png
t09-close.png
t09-open.png
t09-stroke.png
t10-close.png
t10-open.png
t10-stroke.png
t11-close.png
t11-open.png
t11-stroke.png
t12-close.png
t12-open.png
t12-stroke.png
t13-close.png
t13-open.png
t13-stroke.png
t14-close.png
t14-open.png
t14-stroke.png
t15-close.png
t15-open.png
t15-stroke.png
t16-close.png
t16-open.png
t16-stroke.png
t17-close.png
t17-open.png
t17-stroke.png
t18-close.png
t18-open.png
t18-stroke.png
t19-close.png
t19-open.png
t19-stroke.png
t20-close.png
t20-open.png
t20-stroke.png

find-max-min.sh

#!/bin/bash

#
# This saves me the work of having to go through each set of png files and find the max X, and max Y
# to create a DOM element that is big enough to hold all the images inside.
#
get_dimensions () 
{

    for i in {1..20}
    do
        if [ $i -lt 10 ]
        then 
            i="0$i"
        fi

        open="t$i-open.png"
        stroke="t$i-stroke.png"
        close="t$i-close.png"

        # 
        # Explanation: 

        # 1. Use `file` command to extract the dimensions of the PNG
        #   credit: http://superuser.com/a/275507
        # 
        # > file t01-open.png
        # t01-open.png: PNG image data, 178 x 116, 8-bit/color RGBA, non-interlaced
        #
        # 2. use `cut` to split on a comma and return the 2nd field
        # 3. use `sed` to chop away spaces
        #
        open_xy=$(file $open | cut -d ',' -f 2 | sed 's/ //g')
        stroke_xy=$(file $stroke | cut -d ',' -f 2 | sed 's/ //g')
        close_xy=$(file $close | cut -d ',' -f 2 | sed 's/ //g')

        # Cut out the X position, this time splitting on the "x"
        open_x=$(echo $open_xy | cut -d 'x' -f 1)
        stroke_x=$(echo $stroke_xy | cut -d 'x' -f 1)
        close_x=$(echo $close_xy | cut -d 'x' -f 1)

        # Cut the Y position
        open_y=$(echo $open_xy | cut -d 'x' -f 2)
        stroke_y=$(echo $stroke_xy | cut -d 'x' -f 2)
        close_y=$(echo $close_xy | cut -d 'x' -f 2)

        # Get the largest X and Y
        # This is a cheap trick, we will `sort` to organize the numbers in reverse 
        # and just pop off the first one ...
        maxX=$(echo -e "$open_x\n$stroke_x\n$close_x" | sort -n -r | head -1)
        maxY=$(echo -e "$open_y\n$stroke_y\n$close_y" | sort -n -r | head -1)

        echo "t$i $open_xy $stroke_xy $close_xy $maxX $maxY" | awk '{printf "%-5s %-10s %-10s %-10s %s x %s\n", $1, $2, $3, $4, $5, $6 }'

    done
}

results=$(get_dimensions)
echo "Key,Open,Stroke,Close,Max Dimensions " | awk -F ',' '{printf "%-5s %-10s %-10s %-10s %s\n", $1, $2, $3, $4, $5}'
echo "-------------------------------------------------------"
echo "$results"
# Bash note, `echo $results` won't have any of the newlines... we need the quotes to 
# preserve the \n

echo
echo "Stylus CSS Processor Output ... mmm copy/paste"
echo "-------------------------------------------------------"
for l in "$results"
do
    echo "$l" | awk '{printf "#%s \n    width %spx\n    height %spx\n", $1, $5, $7}'
done

output.txt

Key   Open       Stroke     Close      Max Dimensions 
-------------------------------------------------------
t01   178x116    172x81     192x97     192 x 116
t02   104x93     93x81      102x89     104 x 93
t03   98x69      96x52      102x58     102 x 69
t04   121x94     94x88      121x101    121 x 101
t05   123x82     118x60     130x73     130 x 82
t06   97x94      71x85      72x89      97 x 94
t07   114x90     112x75     115x81     115 x 90
t08   102x107    81x89      102x106    102 x 107
t09   126x98     114x69     130x80     130 x 98
t10   74x109     70x92      74x100     74 x 109
t11   112x214    115x207    113x222    115 x 222
t12   105x120    83x95      104x115    105 x 120
t13   111x98     111x68     112x80     112 x 98
t14   69x103     71x86      73x91      73 x 103
t15   106x118    85x88      106x95     106 x 118
t16   112x214    115x207    113x222    115 x 222
t17   83x71      79x56      79x61      83 x 71
t18   94x83      81x69      92x74      94 x 83
t19   71x66      67x56      74x58      74 x 66
t20   79x94      75x81      76x86      79 x 94

Stylus CSS Processor Output ... mmm copy/paste
-------------------------------------------------------
#t01 
    width 192px
    height 116px
#t02 
    width 104px
    height 93px
#t03 
    width 102px
    height 69px
#t04 
    width 121px
    height 101px
#t05 
    width 130px
    height 82px
#t06 
    width 97px
    height 94px
#t07 
    width 115px
    height 90px
#t08 
    width 102px
    height 107px
#t09 
    width 130px
    height 98px
#t10 
    width 74px
    height 109px
#t11 
    width 115px
    height 222px
#t12 
    width 105px
    height 120px
#t13 
    width 112px
    height 98px
#t14 
    width 73px
    height 103px
#t15 
    width 106px
    height 118px
#t16 
    width 115px
    height 222px
#t17 
    width 83px
    height 71px
#t18 
    width 94px
    height 83px
#t19 
    width 74px
    height 66px
#t20 
    width 79px
    height 94px