45 lines
1.2 KiB
Perl
45 lines
1.2 KiB
Perl
use strict;
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use warnings;
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use Imager;
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use constant pi => 3.14159265;
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sub hough {
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my($im) = shift;
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my($width) = shift || 460;
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my($height) = shift || 360;
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$height = 2 * int $height/2;
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$height = 2 * int $height/2;
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my($xsize, $ysize) = ($im->getwidth, $im->getheight);
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my $ht = Imager->new(xsize => $width, ysize => $height);
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my @canvas;
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for my $i (0..$height-1) { for my $j (0..$width-1) { $canvas[$i][$j] = 255 } }
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$ht->box(filled => 1, color => 'white');
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my $rmax = sqrt($xsize**2 + $ysize**2);
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my $dr = 2 * $rmax / $height;
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my $dth = pi / $width;
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for my $x (0..$xsize-1) {
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for my $y (0..$ysize-1) {
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my $col = $im->getpixel(x => $x, y => $y);
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my($r,$g,$b) = $col->rgba;
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next if $r==255; # && $g==255 && $b==255;
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for my $k (0..$width) {
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my $th = $dth*$k;
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my $r2 = ($x*cos($th) + $y*sin($th));
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my $iry = ($height/2 + int($r2/$dr + 0.5));
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$ht->setpixel(x => $k, y => $iry, color => [ ($canvas[$iry][$k]--) x 3] );
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}
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}
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}
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return $ht;
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}
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my $img = Imager->new;
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$img->read(file => 'ref/pentagon.png') or die "Cannot read: ", $img->errstr;
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my $ht = hough($img);
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$ht->write(file => 'hough_transform.png');
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