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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)

Summary

Description
English: Gradual JPEG artifacts example, with decreasing quality from right to left
Date
Source Felis_silvestris_silvestris.jpg
Author
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.

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

w:en:Creative Commons
attribution
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

Captions

Example of the relationship between compression rate to quality of a .jpg image file. The rate is high compression to low quality.

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/TimeThumbnailDimensionsUserComment
current16:22, 25 May 2022Thumbnail for version as of 16:22, 25 May 2022519 × 600 (156 KB)TilmannRThis 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 2022Thumbnail for version as of 08:59, 11 April 2022519 × 600 (94 KB)PhreneticcReduced "weight" of the file.
15:42, 4 March 2017Thumbnail for version as of 15:42, 4 March 2017519 × 600 (156 KB)GnashOptimized
21:28, 3 October 2011Thumbnail for version as of 21:28, 3 October 2011519 × 600 (278 KB)AzaToth

Global file usage

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