File Coverage

lib/Image/Info/JPEG.pm

Criterion	Covered	Total	%
statement	130	144	90.2
branch	54	82	65.8
condition	14	31	45.1
subroutine	13	15	86.6
pod	0	9	0.0
total	211	281	75.0

package Image::Info::JPEG;

# Copyright 1999-2000, Gisle Aas.
#
# This library is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.

# maintained by Tels 2007 - 2008

$VERSION = 0.06;

=begin register

MAGIC: /^\xFF\xD8/

For JPEG files we extract information both from C and C
application chunks.

C is the file format written by most digital cameras. This
encode things like timestamp, camera model, focal length, exposure
time, aperture, flash usage, GPS position, etc.

The C spec can be found at:
L.

The C element may have the following values: C,
C, and C. Note that detecting C and C
currently does not work, but will hopefully in future.

=end register

=cut

use strict;

my %sof = (
   0xC0 => "Baseline",
   0xC1 => "Extended sequential",
   0xC2 => "Progressive",
   0xC3 => "Lossless",
   0xC5 => "Differential sequential",
   0xC6 => "Differential progressive",
   0xC7 => "Differential lossless",
   0xC9 => "Extended sequential, arithmetic coding",
   0xCA => "Progressive, arithmetic coding",
   0xCB => "Lossless, arithmetic coding",
   0xCD => "Differential sequential, arithmetic coding",
   0xCE => "Differential progressive, arithmetic coding",
   0xCF => "Differential lossless, arithmetic coding",
);

sub my_read
{
    my($source, $len) = @_;
    my $buf;
    my $n = read($source, $buf, $len);
    die "read failed: $!" unless defined $n;
    die "short read ($len/$n) at pos " . tell($source) unless $n == $len;
    $buf;
}

BEGIN {
    my $f = ($] >= 5.008) ? <<'EOT' : <<'EOT';
        sub with_io_string (&$) {
	    open(my $fh, "<", \$_[1]);
	    local $_ = $fh;
	    &{$_[0]};
	}
EOT
	sub with_io_string (&$) {
	    require IO::String;
	    local $_ = IO::String->new($_[1]);
	    &{$_[0]};
	    $_->close;
	}
EOT

    #print $f;
    eval $f;
    die $@ if $@;
}

sub process_file
{
    my($info, $fh, $cnf) = @_;
    _process_file($info, $fh, 0);
}

sub _process_file
{
    my($info, $fh, $img_no) = @_;

    my $soi = my_read($fh, 2);
    unless ($soi eq "\xFF\xD8") {
	my $ofs = tell() - 2;
	die "SOI missing in JPEG file at offset $ofs";
    }

    $info->push_info($img_no, "file_media_type" => "image/jpeg");
    $info->push_info($img_no, "file_ext" => "jpg");

    while (1) {
        my($ff, $mark) = unpack("CC", my_read($fh, 2));
	last if !defined $ff;
        if ($ff != 0xFF) {
	    my $corrupt_bytes = 2;
	    while(1) {
		my($ff) = unpack("C", my_read($fh,1));
		return if !defined $ff;
		last if $ff == 0xFF;
		$corrupt_bytes++;
	    }
	    $mark = unpack("C", my_read($fh,1));
	    $info->push_info($img_no, "Warn", sprintf("Corrupt JPEG data, $corrupt_bytes extraneous bytes before marker 0x%02x", $mark));
	}
	if ($mark == 0xFF) {
	    # JPEG markers can be padded with unlimited 0xFF's
	    for (;;) {
		($mark) = unpack("C", my_read($fh, 1));
		last if $mark != 0xFF;
            }
	}
        last if $mark == 0xDA || $mark == 0xD9;  # SOS/EOI
	my($len) = unpack("n", my_read($fh, 2));
	last if $len < 2;
        process_chunk($info, $img_no, $mark, my_read($fh, $len - 2));
    }
}

sub process_chunk
{
    my($info, $img_no, $mark, $data) = @_;
    #printf "MARK 0x%02X, len=%d\n", $mark, length($data);

    if ($mark == 0xFE) {
        $info->push_info($img_no, Comment => $data);
    }
    elsif ($mark >= 0xE0 && $mark <= 0xEF) {
        process_app($info, $mark, $data) if $img_no == 0;
    }
    elsif ($sof{$mark}) {
        my($precision, $height, $width, $num_comp) =
            unpack("CnnC", substr($data, 0, 6, ""));
	$info->push_info($img_no, "JPEG_Type", $sof{$mark});

	# fix bug #15167 by keeping the highest values
	my $old_w = $info->get_info($img_no, "width") || -1;
	my $old_h = $info->get_info($img_no, "height") || -1;

	$info->replace_info($img_no, "width", $width) if $old_w < $width;
	$info->replace_info($img_no, "height", $height) if $old_h < $height;

	for (1..$num_comp) {
	    $info->push_info($img_no, "BitsPerSample", $precision);
	}
	$info->push_info($img_no, "SamplesPerPixel" => $num_comp);

	# XXX need to consider JFIF/Adobe markers to determine this...
	if ($num_comp == 1) {
	    $info->push_info($img_no, "color_type" => "Gray");
	}
	elsif ($num_comp == 3) {
	    $info->push_info($img_no, "color_type" => "YCbCr");  # or RGB ?
	}
	elsif ($num_comp == 4) {
	    $info->push_info($img_no, "color_type" => "CMYK");  # or YCCK ?
	}

	if (1) {
	    my %comp_id_lookup = ( 1 => "Y",
				   2 => "Cb",
				   3 => "Cr",
				   82 => "R",
				   71 => "G",
				   66 => "B" );
	    while (length($data)) {
		my($comp_id, $hv, $qtable) =
		    unpack("CCC", substr($data, 0, 3, ""));
		my $horiz_sf = $hv >> 4 & 0x0f;
		my $vert_sf = $hv & 0x0f;
		$comp_id = $comp_id_lookup{$comp_id} || $comp_id;
		$info->push_info($img_no, "ColorComponents",  [$comp_id, $hv, $qtable]);
		$info->push_info($img_no, "ColorComponentsDecoded",
				 { ComponentIdentifier => $comp_id,
				   HorizontalSamplingFactor => $horiz_sf,
				   VerticalSamplingFactor => $vert_sf,
				   QuantizationTableDesignator => $qtable } );
	    }
	}
    }
}

sub process_app
{
    my($info, $mark, $data) = @_;
    my $app = $mark - 0xE0;
    my $id = substr($data, 0, 5, "");
    #$info->push_info(0, "Debug", "APP$app $id");
    $id = "$app-$id";
    if ($id eq "0-JFIF\0") {
	process_app0_jfif($info, $data);
    }
    elsif ($id eq "0-JFXX\0") {
	process_app0_jfxx($info, $data);
    }
    elsif ($id eq "1-Exif\0") {
	process_app1_exif($info, $data);
    }
    elsif ($id eq "14-Adobe") {
	process_app14_adobe($info, $data);
    }
    else {
	$info->push_info(0, "App$id", $data);
	#printf "  %s\n", Data::Dump::dump($data);
    }
}

sub process_app0_jfif
{
    my($info, $data) = @_;
    if (length $data < 9) {
	$info->push_info(0, "Debug", "Short JFIF chunk");
	return;
    }
    my($ver_hi, $ver_lo, $unit, $x_density, $y_density, $x_thumb, $y_thumb) =
	unpack("CC C nn CC", substr($data, 0, 9, ""));
    $info->push_info(0, "JFIF_Version", sprintf("%d.%02d", $ver_hi, $ver_lo));

    my $res = $x_density != $y_density || !$unit
	? "$x_density/$y_density" : $x_density;

    if ($unit) {
	$unit = { 0 => "pixels",
		  1 => "dpi",
		  2 => "dpcm"
		}->{$unit} || "jfif-unit-$unit";
	$res .= " $unit";
    }
    $info->push_info(0, "resolution", $res);

    if ($x_thumb || $y_thumb) {
	$info->push_info(1, "width", $x_thumb);
	$info->push_info(1, "height", $y_thumb);
	$info->push_info(1, "ByteCount", length($data));
    }
}

sub process_app0_jfxx
{
    my($info, $data) = @_;
    my($code) = ord(substr($data, 0, 1, ""));
    $info->push_info(1, "JFXX_ImageType",
		     { 0x10 => "JPEG thumbnail",
		       0x11 => "Bitmap thumbnail",
		       0x13 => "RGB thumbnail",
		     }->{$code} || "Unknown extension code $code");

    if ($code == 0x10) {
	eval {
	    with_io_string {
		_process_file($info, $_, 1);
	    } $data;
	};
	$info->push_info(1, "error" => $@) if $@;
    }
}

sub process_app1_exif
{
    my($info, $data) = @_;
    my $null = substr($data, 0, 1, "");
    if ($null ne "\0") {
	$info->push_info(0, "Debug", "Exif chunk does not start with \\0");
	return;
    }

    require Image::TIFF;
    my $t = eval { Image::TIFF->new(\$data) };
    if (!$t) {
	$info->push_info(0, "Warn", "Cannot parse APP1 EXIF segment");
	return;
    }


    for my $i (0 .. $t->num_ifds - 1) {
	my $ifd = $t->ifd($i);

#	use Data::Dumper;
#	print STDERR Dumper($ifd);

	for (@$ifd) {
#		use Devel::Peek;
#		print STDERR "# pushing info $i $_->[0] $_->[3]\n";
#		print STDERR Devel::Peek::Dump($_->[3]),"\n" if $_->[0] =~ /Olympus-/;

	    $info->push_info($i, $_->[0], $_->[3]);
	}

	# If we find JPEGInterchangeFormat/JPEGInterchangeFormatLngth,
	# then we should apply process_file kind of recursively to extract
	# information of this (thumbnail) image file...
	if (my($ipos) = $info->get_info($i, "JPEGInterchangeFormat", 1)) {
	    my($ilen) = $info->get_info($i, "JPEGInterchangeFormatLength", 1);
	    if ($ilen)
		{
		my $jdata = substr($data, $ipos, $ilen);
		#$info->push_info($i, "JPEGImage" => $jdata);

		if ($jdata) {
		    with_io_string {
			_process_file($info, $_, $i);
		    } $jdata;
		}
	    }
	}

	# Turn XResolution/YResolution into 'resolution'
	my($xres) = $info->get_info($i, "XResolution", 1);
	my($yres) = $info->get_info($i, "YResolution", 1);

	# Samsung Digimax 200 is a totally confused camera that
	# puts rational numbers with 0 as denominator and they
	# also seem to not understand what resolution means.
	for ($xres, $yres) {
	    $_ += 0 if ref($_) eq "Image::TIFF::Rational";
	}

	my($unit) = $info->get_info($i, "ResolutionUnit", 1);
	my $res = "1/1";  # default;
	if ($xres && $yres) {
	    $res = ($xres == $yres) ? $xres : "$xres/$yres";
	}
	$res .= " $unit" if $unit && $unit ne "pixels";
	$info->push_info($i, "resolution", $res);
    }
}

sub process_app14_adobe
{
    my($info, $data) = @_;
    my($version, $flags0, $flags1, $transform) = unpack("nnnC", $data);
    $info->push_info(0, "AdobeTransformVersion" => $version);
    $info->push_info(0, "AdobeTransformFlags" => [$flags0, $flags1]);
    $info->push_info(0, "AdobeTransform" => $transform);
}

1;