Grayscale image: Difference between revisions

Line 1,115:

end</lang>

=={{header|Perl}}==

=={{header|Perl 6}}==

This script expects to be fed a P6 .ppm file name at the command line. It will convert it to grey scale and save it as a binary portable grey map (P5 .pgm) file.

<lang perl6>sub MAIN ($filename = 'default.ppm') {

my $in = open($filename, :r, :enc<iso-8859-1>);

my ($type, $dim, $depth) = $in.lines[^3];

Since we are using Imlib2, this one '''does''' '''not''' implement really a gray-scale (single channel) storage; it only ''converts'' an RGB image to an RGB image with the same three colour components for each pixel (which result in a gray-scale-like image)

my $outfile = $filename.subst('.ppm', '.pgm');

<lang perl>#! /usr/bin/perl

my $out = open($outfile, :w, :enc<iso-8859-1>);

$out.say("P5\n$dim\n$depth");

use strict;

use Image::Imlib2;

for $in.lines.ords -> $r, $g, $b {

sub tograyscale

⚫

my $gs = $r * 0.2126 + $g * 0.7152 + $b * 0.0722;

{

my $~~img~~ = ~~shift~~;

$out.print: chr($gs min 255);

my $gimg = Image::Imlib2->new($img->width, $img->height);

for ( my $x = 0; $x < $gimg->width; $x++ ) {

for ( my $y = 0; $y < $gimg->height; $y++ ) {

my ( $r, $g, $b, $a ) = $img->query_pixel($x, $y);

⚫

my $~~gray~~ = ~~int(~~0.2126 * $r + 0.7152 * $g + 0.0722 * $b);

# discard alpha info...

$gimg->set_color($gray, $gray, $gray, 255);

$gimg->draw_point($x, $y);

}

return $gimg;

}

$in.close;

my $animage = Image::Imlib2->load("Lenna100.jpg");

$out.close;

my $gscale = tograyscale($animage);

⚫

}</lang>

$gscale->set_quality(80);

Using the .ppm file from the [[Bitmap/Write a PPM file#Perl 6|Write a PPM file]] task:

$gscale->save("Lennagray.jpg");

Original: [[File:Ppm-perl6.png]] Grey Scale: [[File:Pgm-g2-perl6.png]]

⚫

~~exit 0;~~</lang>

=={{header|Perl 6}}==

This script expects to be fed a P6 .ppm file name at the command line. It will convert it to grey scale and save it as a binary portable grey map (P5 .pgm) file.