Re^3: working with png data

The decoding is more different than I thought:

use warnings;
use strict;
use GD::Simple;
use Imager;
$\="\n";
my @txt; $txt[0]="       GD::Simple   <=>        Imager";
my ($x1,$x2,$y)=(1375,1395,29);

print "Line $y: Pixel $x1->$x2 ";

my $png = GD::Image->newFromPng('test.png');  
my ($width, $height) = $png->getBounds;
print "GD::Simple Image dimensions: height = $height, width = $width";
for my $x ( $x1 .. $x2 )      
{ my @c=$png->rgb($png->getPixel($x,$y));
  push (@txt,sprintf("%4d: [%3d,%3d,%3d]",$x,@c));
} 

my $i = Imager-> new;
$i->read(file => 'test.png') or die "Cannot read: ", $i->errstr;
$width  = $i->getwidth();
$height = $i->getheight();
print "Imager     Image dimensions: height = $height, width = $width\n
+";

for my $x ( $x1 .. $x2 )      
{ my $color = $i->getpixel( x => $x, y => $y );
  my ( $r, $g, $b,$a ) = $color->rgba();
  $txt[$x-$x1+1].=sprintf(" <=> %4d: [%3d,%3d,%3d]",$x,$r,$g,$b);
}
 
print $_ foreach @txt;
[download]

The output for my example is:

Line 29: Pixel 1375->1395
GD::Simple Image dimensions: height = 2560, width = 1600
Imager     Image dimensions: height = 2560, width = 1600

       GD::Simple   <=>        Imager
1375: [  4,  2,  4] <=> 1375: [  1,  1,  1]
1376: [  4,  2,  4] <=> 1376: [  1,  1,  1]
1377: [  4,  2,  4] <=> 1377: [  1,  1,  1]
1378: [  4,  2,  4] <=> 1378: [  1,  1,  1]
1379: [ 12, 13, 12] <=> 1379: [ 11, 11, 11]
1380: [ 28, 28, 28] <=> 1380: [ 31, 31, 31]
1381: [ 68, 68, 68] <=> 1381: [ 61, 61, 61]
1382: [100,100,100] <=> 1382: [100,100,100]
1383: [100,100,100] <=> 1383: [102,102,102]
1384: [ 68, 68, 68] <=> 1384: [ 68, 68, 68]
1385: [ 52, 52, 52] <=> 1385: [ 48, 48, 48]
1386: [ 36, 34, 36] <=> 1386: [ 40, 40, 40]
1387: [ 36, 34, 36] <=> 1387: [ 33, 33, 33]
1388: [ 20, 26, 28] <=> 1388: [ 26, 26, 26]
1389: [ 20, 20, 20] <=> 1389: [ 20, 20, 20]
1390: [ 12, 13, 12] <=> 1390: [ 14, 14, 14]
1391: [  4, 10, 12] <=> 1391: [  9,  9,  9]
1392: [  4,  6,  4] <=> 1392: [  6,  6,  6]
1393: [  4,  2,  4] <=> 1393: [  4,  4,  4]
1394: [  4,  2,  4] <=> 1394: [  2,  2,  2]
1395: [  4,  2,  4] <=> 1395: [  1,  1,  1]
[download]

Comment on Re^3: working with png data Select or Download Code

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Re^4: working with png data by vr (Curate) on Sep 11, 2019 at 08:47 UTC
I could not manage to install PDL yet. Prerequisite 'Module::Compile' is not passing for WIN 10 (report). Only one test is failing.(data1_t). Any idea what I could do here ? Force install ? I've never tried to compile PDL from source on Windows. Try Strawberry Perl PDL edition. PDL::IO::Image still needs to be installed from CPAN though. The decoding is more different than I thought GD documentation is misleading -- without forcing an image to remain true color, it's appears to be palettized on open: use strict; use warnings; use GD; use Imager; system 'convert rose: -resize 50% rose.png'; for my $force_true_color ( 0, 1 ) { my $png = GD::Image-> newFromPng( 'rose.png', $force_true_color ); print "GD, \$force_true_color is $force_true_color:\n"; for my $y ( 0 .. 4 ) { for my $x ( 0 .. 4 ) { my @c = $png-> rgb( $png-> getPixel( $x, $y )); print join '/', @c; print "\t"; } print "\n"; } print "\n"; } my $i = Imager-> new( file => 'rose.png' ); print "Imager:\n"; for my $y ( 0 .. 4 ) { for my $x ( 0 .. 4 ) { my @c = $i-> getpixel( x => $x, y => $y )-> rgba; pop @c; print join '/', @c; print "\t"; } print "\n"; } print "\n"; system 'convert rose.png -crop 5x5+0+0 txt:-'; __END__ GD, $force_true_color is 0: 52/48/45 52/48/45 60/50/46 52/48/45 60/50/ +46 44/48/44 44/48/44 52/40/40 44/41/44 52/48/ +45 44/48/44 44/48/44 52/48/45 44/41/44 44/41/ +44 52/55/45 60/56/50 60/56/50 60/50/46 52/48/ +45 60/56/50 60/62/68 68/68/52 76/66/53 68/60/ +51 GD, $force_true_color is 1: 48/47/45 54/50/46 57/49/44 56/48/45 56/49/ +45 44/45/46 47/45/43 48/43/40 46/43/43 49/44/ +43 45/47/47 47/47/46 48/45/42 44/41/41 42/41/ +43 53/54/47 57/56/50 62/56/52 59/52/48 54/51/ +51 56/57/51 64/63/57 70/66/62 72/67/60 70/59/ +47 Imager: 48/47/45 54/50/46 57/49/44 56/48/45 56/49/ +45 44/45/46 47/45/43 48/43/40 46/43/43 49/44/ +43 45/47/47 47/47/46 48/45/42 44/41/41 42/41/ +43 53/54/47 57/56/50 62/56/52 59/52/48 54/51/ +51 56/57/51 64/63/57 70/66/62 72/67/60 70/59/ +47 # ImageMagick pixel enumeration: 5,5,255,srgb 0,0: (48,47,45) #302F2D srgb(48,47,45) 1,0: (54,50,46) #36322E srgb(54,50,46) 2,0: (57,49,44) #39312C srgb(57,49,44) 3,0: (56,48,45) #38302D srgb(56,48,45) 4,0: (56,49,45) #38312D srgb(56,49,45) 0,1: (44,45,46) #2C2D2E srgb(44,45,46) 1,1: (47,45,43) #2F2D2B srgb(47,45,43) 2,1: (48,43,40) #302B28 srgb(48,43,40) 3,1: (46,43,43) #2E2B2B srgb(46,43,43) 4,1: (49,44,43) #312C2B srgb(49,44,43) 0,2: (45,47,47) #2D2F2F srgb(45,47,47) 1,2: (47,47,46) #2F2F2E srgb(47,47,46) 2,2: (48,45,42) #302D2A srgb(48,45,42) 3,2: (44,41,41) #2C2929 srgb(44,41,41) 4,2: (42,41,43) #2A292B srgb(42,41,43) 0,3: (53,54,47) #35362F srgb(53,54,47) 1,3: (57,56,50) #393832 srgb(57,56,50) 2,3: (62,56,52) #3E3834 srgb(62,56,52) 3,3: (59,52,48) #3B3430 srgb(59,52,48) 4,3: (54,51,51) #363333 srgb(54,51,51) 0,4: (56,57,51) #383933 srgb(56,57,51) 1,4: (64,63,57) #403F39 srgb(64,63,57) 2,4: (70,66,62) #46423E srgb(70,66,62) 3,4: (72,67,60) #48433C srgb(72,67,60) 4,4: (70,59,47) #463B2F srgb(70,59,47) [download]	[reply] [d/l]
Re^5: working with png data by Anonymous Monk on Sep 26, 2019 at 10:31 UTC
Many Thanks for your good help !! Setting the option force_true_color is solving the difference completly ! Special thanks to point to Strawberry Perl. Using Strawberry solves some of my install problems !	[reply]


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