254 lines
7.5 KiB
Perl
254 lines
7.5 KiB
Perl
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#------------------------------------------------------------------------------
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# File: BPG.pm
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#
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# Description: Read BPG meta information
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#
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# Revisions: 2016-07-05 - P. Harvey Created
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#
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# References: 1) http://bellard.org/bpg/
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#------------------------------------------------------------------------------
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package Image::ExifTool::BPG;
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use strict;
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use vars qw($VERSION);
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use Image::ExifTool qw(:DataAccess :Utils);
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$VERSION = '1.01';
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# BPG information
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%Image::ExifTool::BPG::Main = (
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PROCESS_PROC => \&Image::ExifTool::ProcessBinaryData,
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GROUPS => { 0 => 'File', 1 => 'File', 2 => 'Image' },
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NOTES => q{
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The information listed below is extracted from BPG (Better Portable
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Graphics) images. See L<http://bellard.org/bpg/> for the specification.
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},
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4 => {
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Name => 'PixelFormat',
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Format => 'int16u',
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Mask => 0xe000,
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PrintConv => {
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0 => 'Grayscale',
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1 => '4:2:0 (chroma at 0.5, 0.5)',
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2 => '4:2:2 (chroma at 0.5, 0)',
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3 => '4:4:4',
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4 => '4:2:0 (chroma at 0, 0.5)',
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5 => '4:2:2 (chroma at 0, 0)',
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},
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},
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4.1 => {
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Name => 'Alpha',
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Format => 'int16u',
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Mask => 0x1004,
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BitShift => 0,
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PrintHex => 1,
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PrintConv => {
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0x0000 => 'No Alpha Plane',
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0x1000 => 'Alpha Exists (color not premultiplied)',
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0x1004 => 'Alpha Exists (color premultiplied)',
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0x0004 => 'Alpha Exists (W color component)',
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},
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},
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4.2 => {
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Name => 'BitDepth',
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Format => 'int16u',
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Mask => 0x0f00,
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ValueConv => '$val + 8',
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},
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4.3 => {
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Name => 'ColorSpace',
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Format => 'int16u',
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Mask => 0x00f0,
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PrintConv => {
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0 => 'YCbCr (BT 601)',
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1 => 'RGB',
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2 => 'YCgCo',
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3 => 'YCbCr (BT 709)',
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4 => 'YCbCr (BT 2020)',
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5 => 'BT 2020 Constant Luminance',
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},
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},
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4.4 => {
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Name => 'Flags',
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Format => 'int16u',
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Mask => 0x000b,
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PrintConv => { BITMASK => {
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0 => 'Animation',
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1 => 'Limited Range',
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3 => 'Extension Present',
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}},
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},
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6 => { Name => 'ImageWidth', Format => 'var_ue7' },
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7 => { Name => 'ImageHeight', Format => 'var_ue7' },
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# length of image data or 0 to EOF
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# (must be decoded so we know where the extension data starts)
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8 => { Name => 'ImageLength', Format => 'var_ue7' },
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);
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%Image::ExifTool::BPG::Extensions = (
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GROUPS => { 0 => 'File', 1 => 'File', 2 => 'Image' },
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VARS => { ALPHA_FIRST => 1 },
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1 => {
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Name => 'EXIF',
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SubDirectory => {
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TagTable => 'Image::ExifTool::Exif::Main',
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ProcessProc => \&Image::ExifTool::ProcessTIFF,
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},
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},
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2 => {
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Name => 'ICC_Profile',
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SubDirectory => { TagTable => 'Image::ExifTool::ICC_Profile::Main' },
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},
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3 => {
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Name => 'XMP',
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SubDirectory => { TagTable => 'Image::ExifTool::XMP::Main' },
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},
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4 => {
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Name => 'ThumbnailBPG',
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Binary => 1,
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},
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5 => {
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Name => 'AnimationControl',
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Binary => 1,
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Unknown => 1,
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},
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);
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#------------------------------------------------------------------------------
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# Get ue7 integer from binary data (max 32 bits)
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# Inputs: 0) data ref, 1) location in data (undef for 0)
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# Returns: 0) ue7 as integer or undef on error, 1) length of ue7 in bytes
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sub Get_ue7($;$)
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{
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my $dataPt = shift;
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my $pos = shift || 0;
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my $size = length $$dataPt;
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my $val = 0;
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my $i;
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for ($i=0; ; ) {
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return() if $pos+$i >= $size or $i >= 5;
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my $byte = Get8u($dataPt, $pos + $i);
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$val = ($val << 7) | ($byte & 0x7f);
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unless ($byte & 0x80) {
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return() if $i == 4 and $byte & 0x70; # error if bits 32-34 are set
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last; # this was the last byte
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}
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return() if $i == 0 and $byte == 0x80; # error if first byte is 0x80
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++$i; # step to the next byte
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}
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return($val, $i+1);
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}
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#------------------------------------------------------------------------------
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# Extract EXIF information from a BPG image
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# Inputs: 0) ExifTool object reference, 1) dirInfo reference
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# Returns: 1 on success, 0 if this wasn't a valid BPG file
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sub ProcessBPG($$)
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{
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local $_;
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my ($et, $dirInfo) = @_;
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my $raf = $$dirInfo{RAF};
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my ($buff, $size, $n, $len, $pos);
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# verify this is a valid BPG file
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return 0 unless $raf->Read($buff, 21) == 21; # (21 bytes is maximum header length)
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return 0 unless $buff =~ /^BPG\xfb/;
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$et->SetFileType(); # set the FileType tag
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SetByteOrder('MM');
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my %dirInfo = (
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DataPt => \$buff,
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DirStart => 0,
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DirLen => length($buff),
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VarFormatData => [ ],
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);
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$et->ProcessDirectory(\%dirInfo, GetTagTable('Image::ExifTool::BPG::Main'));
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return 1 unless $$et{VALUE}{Flags} & 0x0008; # all done unless extension flag is set
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# add varSize from last entry in VarFormatData to determine
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# the current read position in the file
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my $dataPos = 9 + $dirInfo{VarFormatData}[-1][1];
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# read extension length
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unless ($raf->Seek($dataPos, 0) and $raf->Read($buff, 5) == 5) {
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$et->Warn('Missing BPG extension data');
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return 1;
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}
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($size, $n) = Get_ue7(\$buff);
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defined $size or $et->Warn('Corrupted BPG extension length'), return 1;
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$dataPos += $n;
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$size > 10000000 and $et->Warn('BPG extension is too large'), return 1;
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unless ($raf->Seek($dataPos, 0) and $raf->Read($buff, $size) == $size) {
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$et->Warn('Truncated BPG extension');
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return 1;
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}
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my $tagTablePtr = GetTagTable('Image::ExifTool::BPG::Extensions');
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# loop through the individual extensions
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for ($pos=0; $pos<$size; $pos+=$len) {
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my $type = Get8u(\$buff, $pos);
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# get length of this extension
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($len, $n) = Get_ue7(\$buff, ++$pos);
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defined $len or $et->Warn('Corrupted BPG extension'), last;
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$pos += $n; # point to start of data for this extension
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$pos + $len > $size and $et->Warn('Invalid BPG extension size'), last;
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$$tagTablePtr{$type} or $et->Warn("Unrecognized BPG extension $type ($len bytes)", 1), next;
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# libbpg (in my opinion) incorrectly copies the padding byte after the
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# "EXIF\0" APP1 header to the start of the BPG EXIF extension, so issue a
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# minor warning and ignore the padding if we find it before the TIFF header
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if ($type == 1 and $len > 3 and substr($buff,$pos,3)=~/^.(II|MM)/s) {
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$et->Warn("Ignored extra byte at start of EXIF extension", 1);
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++$pos;
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--$len;
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}
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$et->HandleTag($tagTablePtr, $type, undef,
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DataPt => \$buff,
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DataPos => $dataPos,
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Start => $pos,
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Size => $len,
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Parent => 'BPG',
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);
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}
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return 1;
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}
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1; # end
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__END__
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=head1 NAME
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Image::ExifTool::BPG - Read BPG meta information
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=head1 SYNOPSIS
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This module is used by Image::ExifTool
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=head1 DESCRIPTION
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This module contains definitions required by Image::ExifTool to read BPG
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(Better Portable Graphics) images.
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=head1 AUTHOR
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Copyright 2003-2018, Phil Harvey (phil at owl.phy.queensu.ca)
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This library is free software; you can redistribute it and/or modify it
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under the same terms as Perl itself.
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=head1 REFERENCES
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=over 4
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=item L<http://bellard.org/bpg/>
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=back
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=head1 SEE ALSO
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L<Image::ExifTool::TagNames/BPG Tags>,
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L<Image::ExifTool(3pm)|Image::ExifTool>
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=cut
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