File:Felis_silvestris_silvestris_small_gradual_decrease_of_quality.png
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Felis_silvestris_silvestris_small_gradual_decrease_of_quality.png (519 × 600 pixels, file size: 156 KB, MIME type: image/png)
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Summary
DescriptionFelis silvestris silvestris small gradual decrease of quality.png |
English: Gradual JPEG artifacts example, with decreasing quality from right to left |
Date | |
Source | Felis_silvestris_silvestris.jpg |
Author |
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Other versions | Derivative works of this file: Felis silvestris silvestris small gradual decrease of quality - JPEG compression.jpg |
This is a retouched picture, which means that it has been digitally altered from its original version. Modifications: Gradual JPEG artifacts example. The original can be viewed here: Felis silvestris silvestris.jpg: . Modifications made by AzaToth.
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Source code
#!/usr/bin/perl
use strict;
use warnings;
use v5.12;
use File::Temp qw/ tempdir /;
use Graphics::Magick;
use Math::Round qw(:all);
my $p = new Graphics::Magick;
$p->Read("Felis_silvestris_silvestris_small.png");
#$p->Resize('x600');
my ($width, $height) = $p->Get('width', 'height');
my $center = $height;
my $result = new Graphics::Magick;
$result->Set(size=>"${width}x${height}");
$result->Read();
$result->Set('quality', 100);
my $dir = tempdir(CLEANUP => 1);
my $chop = 16; # 1 MCU normally
my $vertical = 0;
for my $n (0..($vertical?$height:$width)) {
next if $n%$chop;
my $current = $p->Clone();
$current->Crop(width => $vertical?$width:$chop, height => $vertical?$chop:$height, x => $vertical?0:$n, y=>$vertical?$n:0);
my $quality = round_even(100*abs(($n+6*$chop)**4/$center**4));
say $quality;
$current->Set('quality' => $quality);
my $filename = sprintf "%s/%05d.jpg", $dir, $n;
$current->Write($filename);
my $m = new Graphics::Magick;
$m->Read($filename);
$result->Composite( image => $m, x => $vertical?0:$n, y => $vertical?$n:0);
}
$result->Write('Felis_silvestris_silvestris_small_gradual_decrease_of_quality.png');
Licensing
This file is licensed under the Creative Commons Attribution 3.0 Unported license.
- You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
- Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
Original upload log
This image is a derivative work of the following images:
- File:Felis_silvestris_silvestris.jpg licensed with Cc-by-3.0
- 2010-02-18T00:29:12Z Michael Gäbler 1496x1729 (1659050 Bytes) {{Information |Description=''[[Felis silvestris silvestris|Felis silvestris silvestris]]'' (Schreber, 1775) {{en|1=[[:en: European Wildcat|European Wildcat]]}} {{de|1=[[:de:Europäische Wildkatze|Europäische Wildkatze]] im [
Uploaded with derivativeFX
Items portrayed in this file
depicts
3 October 2011
image/png
File history
Click on a date/time to view the file as it appeared at that time.
Date/Time | Thumbnail | Dimensions | User | Comment | |
---|---|---|---|---|---|
current | 16:22, 25 May 2022 | 519 × 600 (156 KB) | TilmannR | This is an image about JPEG compression artifacts. Therefore quantized re-encoding is undesirable. Reverted to version as of 15:42, 4 March 2017 (UTC) | |
08:59, 11 April 2022 | 519 × 600 (94 KB) | Phreneticc | Reduced "weight" of the file. | ||
15:42, 4 March 2017 | 519 × 600 (156 KB) | Gnash | Optimized | ||
21:28, 3 October 2011 | 519 × 600 (278 KB) | AzaToth |
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