#!/usr/bin/perl

#-- ----------------------------------------------------------------------------
#-- From http://egb13.net/
#-- Last updated: 2011-09-01
#-- ----------------------------------------------------------------------------
#-- Copyright (C) 2011 by EGB13.net
#-- 
#-- Permission is hereby granted, free of charge, to any person obtaining a copy
#-- of this software and associated documentation files (the "Software"), to deal
#-- in the Software without restriction, including without limitation the rights
#-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#-- copies of the Software, and to permit persons to whom the Software is
#-- furnished to do so, subject to the following conditions:
#-- 
#-- The above copyright notice and this permission notice shall be included in
#-- all copies or substantial portions of the Software.
#-- 
#-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#-- THE SOFTWARE.
#-- ----------------------------------------------------------------------------
#-- removes (makes transparent) certain colors in a transparent GIF or PNG file
#-- used to remove noise from NOAA weather radar images, tho at the loss of some
#-- valid low-intensity returns.  Intended for use on the radar-only images from
#-- http://radar.weather.gov/Conus/RadarImg/
#--
#-- lately added "-c" option to specify a single color to remove, used for removing
#-- the black background on images found at http://mesonet.agron.iastate.edu/docs/nexrad_composites/
#--
##-- 2011-09-01: Switch to Image::Magick package as that's what works with
##-- ActiveState Perl for this utility.
#-- ----------------------------------------------------------------------------

my @noise =	(	
			'#019ff4'
		,	'#04e9e7'
		,	'#e3e3e3'
		,	'#e6e6e6'
		,	'#e8e8e8'
		,	'#ebebeb'
		,	'#eeeeee'
		,	'#f0f0f0'
		) ;

my $darkblue = 	'#0300f4' ;	# darkest  blue

use Image::Magick ;	#-- Graphics::Magick may work, too; you'd have to change "Image::" where ever it appears

require 'getopt.pl' ;
sub Usage {	my ($msg) = @_ ;

	print STDERR "$msg" if (defined ($msg) && $msg ne "") ;
	print STDERR "Usage: $0 -i inputfile -o outputfile [-f fuzzfactor] [-x] [-c #xxxxxx]\n" ;
	print STDERR "    fuzzfactor is an integer (default=32)\n    -x to get the extra bit of blue out\n    -c specifies the ONLY color to remove\n" ;
	exit 1 ;
}
&Getopt('iofc') ;

&Usage if (defined ($opt_h) ) ;
&Usage ("Please specify input file\n") if (!defined ($opt_i) ) ;
&Usage ("Please specify output file\n") if (!defined ($opt_i) ) ;
$opt_f = 32 unless defined ($opt_f) ;
&Usage ("Fuzz factor must be an integer.") unless ($opt_f =~ m/^\d+$/) ;
push @noise, $darkblue if (defined ($opt_x) ) ;

if (defined ($opt_c) ) {
	if ($opt_c =~ m/^\#?([0-9a-f]{6})$/i) {		#-- works w/ or w/o the "#" in the argument
		@noise = ( "#".$1 ) ;
	} else {
		&Usage (sprintf "Don't recognize a color value in '%s'; use xxxxxx where 'x' is a hex digit.\n", $opt_c) ;
		exit 1 ;
	}
}


my $img = Image::Magick->new;
my $res = $img->Read($opt_i) ;
die "$opt_i: $!\n" if ($res) ;

$img->Set(colorspace => RGB, type => TrueColor) ;
foreach my $color (@noise) {
	$img->Transparent(color => $color, fuzz => $opt_f) ;
}
$res = $img->write(filename => $opt_o) ;
die "$opt_o: $!\n" if ($res) ;

undef $img ;

exit 0 ;