3
# Read an input image, crop its border to a standard width, and
4
# convert it into a square output image. Parameters are:
6
# - the required total image size
7
# - the output border thickness
8
# - the input image file name
9
# - the output image file name.
11
($osize, $oborder, $infile, $outfile) = @ARGV;
13
# Determine the input image's size.
14
$ident = `identify -format "%w %h" $infile`;
15
$ident =~ /(\d+) (\d+)/ or die "unable to get size for $infile\n";
18
# Read the input image data.
20
open IDATA, "convert -depth 8 $infile rgb:- |";
21
push @$data, $rgb while (read IDATA,$rgb,3,0) == 3;
23
# Check we have the right amount of data.
26
die "wrong amount of image data ($al, expected $xl) from $infile\n"
29
# Find the background colour, by looking around the entire border
30
# and finding the most popular pixel colour.
31
for ($i = 0; $i < $w; $i++) {
32
$pcount{$data->[$i]}++; # top row
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$pcount{$data->[($h-1)*$w+$i]}++; # bottom row
35
for ($i = 1; $i < $h-1; $i++) {
36
$pcount{$data->[$i*$w]}++; # left column
37
$pcount{$data->[$i*$w+$w-1]}++; # right column
39
@plist = sort { $pcount{$b} <=> $pcount{$a} } keys %pcount;
42
# Crop rows and columns off the image to find the central rectangle
43
# of non-background stuff.
45
$ystart++ while $ystart < $h and scalar(grep { $_ ne $back } map { $data->[$ystart*$w+$_] } 0 .. ($w-1)) == 0;
47
$yend-- while $yend >= $ystart and scalar(grep { $_ ne $back } map { $data->[$yend*$w+$_] } 0 .. ($w-1)) == 0;
49
$xstart++ while $xstart < $w and scalar(grep { $_ ne $back } map { $data->[$_*$w+$xstart] } 0 .. ($h-1)) == 0;
51
$xend-- while $xend >= $xstart and scalar(grep { $_ ne $back } map { $data->[$_*$w+$xend] } 0 .. ($h-1)) == 0;
53
# Decide how much border we're going to put back on to make the
54
# image perfectly square.
55
$hexpand = ($yend-$ystart) - ($xend-$xstart);
57
$left = int($hexpand / 2);
59
$xend += $hexpand - $left;
60
} elsif ($hexpand < 0) {
62
$top = int($vexpand / 2);
64
$yend += $vexpand - $top;
66
$ow = $xend - $xstart + 1;
67
$oh = $yend - $ystart + 1;
68
die "internal computation problem" if $ow != $oh; # should be square
70
# And decide how much _more_ border goes on to add the bit around
72
$realow = int($ow * ($osize / ($osize - 2*$oborder)));
73
$extra = $realow - $ow;
74
$left = int($extra / 2);
76
$xend += $extra - $left;
77
$top = int($extra / 2);
79
$yend += $extra - $top;
80
$ow = $xend - $xstart + 1;
81
$oh = $yend - $ystart + 1;
82
die "internal computation problem" if $ow != $oh; # should be square
84
# Now write out the resulting image, and resize it appropriately.
85
open IDATA, "| convert -size ${ow}x${oh} -depth 8 -resize ${osize}x${osize}! rgb:- $outfile";
86
for ($y = $ystart; $y <= $yend; $y++) {
87
for ($x = $xstart; $x <= $xend; $x++) {
88
if ($x >= 0 && $x < $w && $y >= 0 && $y < $h) {
89
print IDATA $data->[$y*$w+$x];