#!/usr/local/bin/perl
## Program name: jpegsize
## Author: Stuart Curtis Lathrop <sclathrop@niitech.com>
## Version: 1.0. July 2000.
## Copyright: This code is placed into the Public Domain under the
## terms of the GNU Public License. No fee may be charged
## for its use or distribution.
##
## Kudos to: Rajiv Pant (Betul) <betul@rajiv.com [URL unfurl="true"]http://rajiv.org>,[/URL]
## author of gifsize.pl
## Jef Poskanzer <jef@acme.com>, author of image_size.c
## and the Independent JPEG Group for their direction!
##
## THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
## ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
## IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
## ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
## FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
## DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
## OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
## HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
## LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
## OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
## SUCH DAMAGE.
##
## Notes: This script will _not_ handle JPEG redefinition of image size
## via DNL marker tag. Files so encoded will either return zero
## width & height (typically) or will generate a tag error.
##
foreach $jpeg (@ARGV)
{
$M_SOI = "\xd8";
$M_BLK = "\xff";
($width, $height, $type) = jpegsize($jpeg);
print "$jpeg width = ", $width, ", height = ", $height;
($type =~ $M_BLK.$M_SOI) ? print "\n" : print "$jpeg is not a JPEG.\n" ;
}
sub jpegsize
{
local ($jpeg) = @_ ;
local ($type, $tag, $marker, $buffer, $lhob, $llob, $blocklen) = ();
local ($whob, $wlob, $hhob, $hlob, $width, $height) = ();
## required jpeg markers
$M_SOF0 = "\xc0";
$M_SOF1 = "\xc1";
$M_SOF2 = "\xc2";
$M_SOF3 = "\xc3";
$M_SOI = "\xd8";
$M_EOI = "\xd9";
$M_SOS = "\xda";
$M_BLK = "\xff";
open (JPEG, "<".$jpeg) || die "Unable to open $jpeg, $!";
binmode (JPEG) || die "Cannot read $jpeg in binary mode, $!";
read (JPEG, $type, 2) || die "Error while reading $jpeg, $!";
## check for jpeg file type (start of image) marker
if (!($type eq $M_BLK.$M_SOI))
{
close(JPEG) || die "Error closing $jpeg, $!";
return ( 0, 0, $type );
}
for (;;)
{
## check for block tag
read (JPEG, $tag, 1) || die "Error while reading $jpeg, $!";
if ($tag ne $M_BLK)
{
print "Error: No start of block marker (0xff) found!\n";
close(JPEG) || die "Error closing $jpeg, $!";
return ( 0, 0, $type );
}
## get marker type & block length
read (JPEG, $marker, 1) || die "Error while reading $jpeg, $!";
read (JPEG, $lhob, 1) || die "Error while reading $jpeg, $!";
read (JPEG, $llob, 1) || die "Error while reading $jpeg, $!";
$blocklen = (ord($lhob) * 256) + ord($llob) - 2;
## check for any start of field marker
if ( $marker ge $M_SOF0 && $marker le $M_SOF3 )
{
## ignore data precision
read (JPEG, $buffer, 1) || die "Error while reading $jpeg, $!";
## read the height and width.
read (JPEG, $hhob, 1) || die "Error while reading $jpeg, $!";
read (JPEG, $hlob, 1) || die "Error while reading $jpeg, $!";
$height = (ord($hhob) * 256) + ord($hlob);
read (JPEG, $whob, 1) || die "Error while reading $jpeg, $!";
read (JPEG, $wlob, 1) || die "Error while reading $jpeg, $!";
$width = (ord($whob) * 256) + ord($wlob);
# ignore components & rest of file...
close(JPEG) || die "Error closing $jpeg, $!";
return ($width, $height, $type);
}
else
{
if ( $marker eq M_SOS || $marker eq M_EOI )
{
## past header data; size indeterminable
close(JPEG) || die "Error closing $jpeg, $!";
return (0, 0, $type);
}
## skip to next marker
read (JPEG, $buffer, $blocklen);
}
}
}
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