/
qzst_encoder.pl
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/
qzst_encoder.pl
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#!/usr/bin/perl
# Variation of the QOI encoder, combined with Zstandard compression.
# See also:
# https://qoiformat.org/
# https://github.com/phoboslab/qoi
use 5.020;
use warnings;
use Imager;
use experimental qw(signatures);
use IO::Compress::Zstd qw(zstd $ZstdError);
sub qzst_encoder ($img, $out_fh) {
use constant {
QOI_OP_RGB => 0b1111_1110,
QOI_OP_RGBA => 0b1111_1111,
QOI_OP_DIFF => 0b01_000_000,
QOI_OP_RUN => 0b11_000_000,
QOI_OP_LUMA => 0b10_000_000,
};
my $width = $img->getwidth;
my $height = $img->getheight;
my $channels = $img->getchannels;
my $colorspace = 0;
say "[$width, $height, $channels, $colorspace]";
my @header = unpack('C*', 'qzst');
push @header, unpack('C4', pack('N', $width));
push @header, unpack('C4', pack('N', $height));
push @header, $channels;
push @header, $colorspace;
my $qoi_data = '';
my $run = 0;
my @px = (0, 0, 0, 255);
my @prev_px = @px;
my @colors = (map { [0, 0, 0, 0] } 1 .. 64);
foreach my $y (0 .. $height - 1) {
my @line = unpack('C*', scalar $img->getscanline(y => $y));
my $line_len = scalar(@line);
for (my $i = 0 ; $i < $line_len ; $i += 4) {
@px = splice(@line, 0, 4);
if ( $px[0] == $prev_px[0]
and $px[1] == $prev_px[1]
and $px[2] == $prev_px[2]
and $px[3] == $prev_px[3]) {
if (++$run == 62) {
$qoi_data .= chr(QOI_OP_RUN | ($run - 1));
$run = 0;
}
}
else {
if ($run > 0) {
$qoi_data .= chr(QOI_OP_RUN | ($run - 1));
$run = 0;
}
my $hash = ($px[0] * 3 + $px[1] * 5 + $px[2] * 7 + $px[3] * 11) % 64;
my $index_px = $colors[$hash];
if ( $px[0] == $index_px->[0]
and $px[1] == $index_px->[1]
and $px[2] == $index_px->[2]
and $px[3] == $index_px->[3]) { # OP INDEX
$qoi_data .= chr($hash);
}
else {
$colors[$hash] = [@px];
if ($px[3] == $prev_px[3]) {
my $vr = $px[0] - $prev_px[0];
my $vg = $px[1] - $prev_px[1];
my $vb = $px[2] - $prev_px[2];
my $vg_r = $vr - $vg;
my $vg_b = $vb - $vg;
if ( $vr > -3
and $vr < 2
and $vg > -3
and $vg < 2
and $vb > -3
and $vb < 2) {
$qoi_data .= chr(QOI_OP_DIFF | (($vr + 2) << 4) | (($vg + 2) << 2) | ($vb + 2));
}
elsif ( $vg_r > -9
and $vg_r < 8
and $vg > -33
and $vg < 32
and $vg_b > -9
and $vg_b < 8) {
$qoi_data .= join('', chr(QOI_OP_LUMA | ($vg + 32)), chr((($vg_r + 8) << 4) | ($vg_b + 8)));
}
else {
$qoi_data .= join('', chr(QOI_OP_RGB), chr($px[0]), chr($px[1]), chr($px[2]));
}
}
else {
$qoi_data .= join('', chr(QOI_OP_RGBA), chr($px[0]), chr($px[1]), chr($px[2]), chr($px[3]));
}
}
}
@prev_px = @px;
}
}
if ($run > 0) {
$qoi_data .= chr(0b11_00_00_00 | ($run - 1));
}
my @footer;
push(@footer, (0x00) x 7);
push(@footer, 0x01);
# Header
print $out_fh pack('C*', @header);
# Compressed data
zstd(\$qoi_data, \my $zstd_data) or die "zstd failed: $ZstdError\n";
print $out_fh pack("N", length($zstd_data));
print $out_fh $zstd_data;
# Footer
print $out_fh pack('C*', @footer);
}
@ARGV || do {
say STDERR "usage: $0 [input.png] [output.qzst]";
exit(2);
};
my $in_file = $ARGV[0];
my $out_file = $ARGV[1] // "$in_file.qzst";
my $img = 'Imager'->new(file => $in_file)
or die "Can't read image: $in_file";
open(my $out_fh, '>:raw', $out_file)
or die "Can't open file <<$out_file>> for writing: $!";
qzst_encoder($img, $out_fh);