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#!/usr/bin/perl
## -----------------------------------------------------------------------
##
## Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, Inc., 53 Temple Place Ste 330,
## Boston MA 02111-1307, USA; either version 2 of the License, or
## (at your option) any later version; incorporated herein by reference.
##
## -----------------------------------------------------------------------
##
## ppmtolss16
##
## Convert a PNM file with max 16 colors to a simple RLE-based format:
##
## uint32 0x1413f33d ; magic (littleendian)
## uint16 xsize ; littleendian
## uint16 ysize ; littleendian
## 16 x uint8 r,g,b ; color map, in 6-bit format (each byte is 0..63)
##
## Then, a sequence of nybbles:
##
## N ... if N is != previous pixel, one pixel of color N
## ... otherwise run sequence follows ...
## M ... if M > 0 then run length is M+1
## ... otherwise run sequence is encoded in two nybbles,
## littleendian, +17
##
## The nybble sequences are on a per-row basis; runs may not extend
## across rows and odd-nybble rows are zero-padded.
##
## At the start of row, the "previous pixel" is assumed to be zero.
##
## Usage:
##
## ppmtolss16 [#rrggbb=i ...] < input.ppm > output.rle
##
## Command line options of the form #rrggbb=i indicate that
## the color #rrggbb (hex) should be assigned index i (decimal)
##
eval { use bytes; };
eval { binmode STDIN; };
eval { binmode STDOUT; };
$magic = 0x1413f33d;
# Get a token from the PPM header. Ignore comments and leading
# and trailing whitespace, as is required by the spec.
# This routine eats exactly one character of trailing whitespace,
# unless it is a comment (in which case it eats the comment up
# to and including the end of line.)
sub get_token() {
my($token, $ch);
my($ch);
do {
$ch = getc(STDIN);
return undef if ( !defined($ch) ); # EOF
if ( $ch eq '#' ) {
do {
$ch = getc(STDIN);
return undef if ( !defined($ch) );
} while ( $ch ne "\n" );
}
} while ( $ch =~ /^[ \t\n\v\f\r]$/ );
$token = $ch;
while ( 1 ) {
$ch = getc(STDIN);
last if ( $ch =~ /^[ \t\n\v\f\r\#]$/ );
$token .= $ch;
}
if ( $ch eq '#' ) {
do {
$ch = getc(STDIN);
} while ( defined($ch) && $ch ne "\n" );
}
return $token;
}
# Get a token, and make sure it is numeric (and exists)
sub get_numeric_token() {
my($token) = get_token();
if ( $token !~ /^[0-9]+$/ ) {
print STDERR "Format error on input\n";
exit 1;
}
return $token + 0;
}
# Must be called before each pixel row is read
sub start_new_row() {
$getrgb_leftover_bit_cnt = 0;
$getrgb_leftover_bit_val = 0;
}
# Get a single RGB token depending on the PNM type
sub getrgb($) {
my($form) = @_;
my($rgb,$r,$g,$b);
if ( $form == 6 ) {
# Raw PPM, most common
return undef unless ( read(STDIN,$rgb,3) == 3 );
return unpack("CCC", $rgb);
} elsif ( $form == 3 ) {
# Plain PPM
$r = get_numeric_token();
$g = get_numeric_token();
$b = get_numeric_token();
return ($r,$g,$b);
} elsif ( $form == 5 ) {
# Raw PGM
return undef unless ( read(STDIN,$rgb,1) == 1 );
$r = unpack("C", $rgb);
return ($r,$r,$r);
} elsif ( $form == 2 ) {
# Plain PGM
$r = get_numeric_token();
return ($r,$r,$r);
} elsif ( $form == 4 ) {
# Raw PBM
if ( !$getrgb_leftover_bit_cnt ) {
return undef unless ( read(STDIN,$rgb,1) == 1 );
$getrgb_leftover_bit_val = unpack("C", $rgb);
$getrgb_leftover_bit_cnt = 8;
}
$r = ( $getrgb_leftover_bit_val & 0x80 ) ? 0x00 : 0xff;
$getrgb_leftover_bit_val <<= 1;
$getrgb_leftover_bit_cnt--;
return ($r,$r,$r);
} elsif ( $form == 1 ) {
# Plain PBM
my($ch);
do {
$ch = getc(STDIN);
return undef if ( !defined($ch) );
return (255,255,255) if ( $ch eq '0' ); # White
return (0,0,0) if ( $ch eq '1'); # Black
if ( $ch eq '#' ) {
do {
$ch = getc(STDIN);
return undef if ( !defined($ch) );
} while ( $ch ne "\n" );
}
} while ( $ch =~ /^[ \t\n\v\f\r]$/ );
return undef;
} else {
die "Internal error: unknown format: $form\n";
}
}
sub rgbconvert($$$$) {
my($r,$g,$b,$maxmult) = @_;
my($rgb);
$r = int($r*$maxmult);
$g = int($g*$maxmult);
$b = int($b*$maxmult);
$rgb = pack("CCC", $r, $g, $b);
return $rgb;
}
foreach $arg ( @ARGV ) {
if ( $arg =~ /^\#([0-9a-f])([0-9a-f])([0-9a-f])=([0-9]+)$/i ) {
$r = hex($1) << 4;
$g = hex($2) << 4;
$b = hex($3) << 4;
$i = $4 + 0;
} elsif ( $arg =~ /^\#([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})=([0-9]+)$/i ) {
$r = hex($1);
$g = hex($2);
$b = hex($3);
$i = $4 + 0;
} elsif ( $arg =~ /^\#([0-9a-f]{3})([0-9a-f]{3})([0-9a-f]{3})=([0-9]+)$/i ) {
$r = hex($1) >> 4;
$g = hex($2) >> 4;
$b = hex($3) >> 4;
$i = $4 + 0;
} elsif ( $arg =~ /^\#([0-9a-f]{4})([0-9a-f]{4})([0-9a-f]{4})=([0-9]+)$/i ) {
$r = hex($1) >> 8;
$g = hex($2) >> 8;
$b = hex($3) >> 8;
$i = $4 + 0;
} else {
print STDERR "$0: Unknown argument: $arg\n";
next;
}
if ( $i > 15 ) {
print STDERR "$0: Color index out of range: $arg\n";
next;
}
$rgb = rgbconvert($r, $g, $b, 64/256);
if ( defined($index_forced{$i}) ) {
print STDERR "$0: More than one color index $i\n";
exit(1);
}
$index_forced{$i} = $rgb;
$force_index{$rgb} = $i;
}
$form = get_token();
die "$0: stdin is not a PNM file" if ( $form !~ /^P([1-6])$/ );
$form = $1+0;
$xsize = get_numeric_token();
$ysize = get_numeric_token();
if ( $form == 1 || $form == 4 ) {
$maxcol = 255; # Internal convention
} else {
$maxcol = get_numeric_token();
}
$maxmult = 64/($maxcol+1); # Equal buckets conversion
@data = ();
for ( $y = 0 ; $y < $ysize ; $y++ ) {
start_new_row();
for ( $x = 0 ; $x < $xsize ; $x++ ) {
die "$0: Premature EOF at ($x,$y) of ($xsize,$ysize)\n"
if ( !defined(@pnmrgb = getrgb($form)) );
# Convert to 6-bit representation
$rgb = rgbconvert($pnmrgb[0], $pnmrgb[1], $pnmrgb[2], $maxmult);
$color_count{$rgb}++;
push(@data, $rgb);
}
}
# Sort list of colors according to freqency
@colors = sort { $color_count{$b} <=> $color_count{$a} } keys(%color_count);
# Now we have our pick of colors. Sort according to intensity;
# this is more or less an ugly hack to cover for the fact that
# using PPM as input doesn't let the user set the color map,
# which the user really needs to be able to do.
sub by_intensity() {
my($ra,$ga,$ba) = unpack("CCC", $a);
my($rb,$gb,$bb) = unpack("CCC", $b);
my($ia) = $ra*0.299 + $ga*0.587 + $ba*0.114;
my($ib) = $rb*0.299 + $gb*0.587 + $bb*0.114;
return ( $ia <=> $ib ) if ( $ia != $ib );
# If same, sort based on RGB components,
# with highest priority given to G, then R, then B.
return ( $ga <=> $gb ) if ( $ga != $gb );
return ( $ra <=> $rb ) if ( $ra != $rb );
return ( $ba <=> $bb );
}
@icolors = sort by_intensity @colors;
# Insert forced colors into "final" array
@colors = (undef) x 16;
foreach $rgb ( keys(%force_index) ) {
$i = $force_index{$rgb};
$colors[$i] = $rgb;
$color_index{$rgb} = $i;
}
undef %force_index;
# Insert remaining colors in the remaining slots,
# in luminosity-sorted order
$nix = 0;
while ( scalar(@icolors) ) {
# Advance to the next free slot
$nix++ while ( defined($colors[$nix]) && $nix < 16 );
last if ( $nix >= 16 );
$rgb = shift @icolors;
if ( !defined($color_index{$rgb}) ) {
$colors[$nix] = $rgb;
$color_index{$rgb} = $nix;
}
}
while ( scalar(@icolors) ) {
$rgb = shift @icolors;
$lost++ if ( !defined($color_index{$rgb}) );
}
if ( $lost ) {
printf STDERR
"$0: Warning: color palette truncated (%d colors ignored)\n", $lost;
}
undef @icolors;
# Output header
print pack("Vvv", $magic, $xsize, $ysize);
# Output color map
for ( $i = 0 ; $i < 16 ; $i++ ) {
if ( defined($colors[$i]) ) {
print $colors[$i];
} else {
# Padding for unused color entries
print pack("CCC", 63*$i/15, 63*$i/15, 63*$i/15);
}
}
sub output_nybble($) {
my($ny) = @_;
if ( !defined($ny) ) {
if ( defined($nybble_tmp) ) {
$ny = 0; # Force the last byte out
} else {
return;
}
}
$ny = $ny & 0x0F;
if ( defined($nybble_tmp) ) {
$ny = ($ny << 4) | $nybble_tmp;
print chr($ny);
$bytes++;
undef $nybble_tmp;
} else {
$nybble_tmp = $ny;
}
}
sub output_run($$$) {
my($last,$this,$run) = @_;
if ( $this != $last ) {
output_nybble($this);
$run--;
}
while ( $run ) {
if ( $run >= 16 ) {
output_nybble($this);
output_nybble(0);
if ( $run > 271 ) {
$erun = 255;
$run -= 271;
} else {
$erun = $run-16;
$run = 0;
}
output_nybble($erun);
output_nybble($erun >> 4);
} else {
output_nybble($this);
output_nybble($run);
$run = 0;
}
}
}
$bytes = 0;
undef $nybble_tmp;
for ( $y = 0 ; $y < $ysize ; $y++ ) {
$last = $prev = 0;
$run = 0;
for ( $x = 0 ; $x < $xsize ; $x++ ) {
$rgb = shift(@data);
$i = $color_index{$rgb} + 0;
if ( $i == $last ) {
$run++;
} else {
output_run($prev, $last, $run);
$prev = $last;
$last = $i;
$run = 1;
}
}
# Output final datum for row; we're always at least one pixel behind
output_run($prev, $last, $run);
output_nybble(undef); # Flush row
}
$pixels = $xsize * $ysize;
$size = ($pixels+1)/2;
printf STDERR "%d pixels, %d bytes, (%2.2f%% compression)\n",
$pixels, $bytes, 100*($size-$bytes)/$size;