File Coverage

blib/lib/Image/ExifTool/SigmaRaw.pm

Criterion	Covered	Total	%
statement	195	222	87.8
branch	87	148	58.7
condition	13	33	39.3
subroutine	10	10	100.0
pod	0	6	0.0
total	305	419	72.7

#------------------------------------------------------------------------------
# File:         SigmaRaw.pm
#
# Description:  Read Sigma/Foveon RAW (X3F) meta information
#
# Revisions:    2005/10/16 - P. Harvey Created
#               2009/11/30 - P. Harvey Support X3F v2.3 written by Sigma DP2
#
# References:   1) http://www.x3f.info/technotes/FileDocs/X3F_Format.pdf
#------------------------------------------------------------------------------

package Image::ExifTool::SigmaRaw;

use strict;
use vars qw($VERSION);
use Image::ExifTool qw(:DataAccess :Utils);
use Image::ExifTool::Sigma;

$VERSION = '1.30';

sub ProcessX3FHeader($$$);
sub ProcessX3FDirectory($$$);
sub ProcessX3FProperties($$$);

# main X3F sections (plus header stuff)
%Image::ExifTool::SigmaRaw::Main = (
    PROCESS_PROC => \&ProcessX3FDirectory,
    NOTES => q{
        These tags are used in Sigma and Foveon RAW (.X3F) images.  Metadata is also
        extracted from the JpgFromRaw image if it exists (all models but the SD9 and
        SD10).  Currently, metadata may only be written to the embedded JpgFromRaw.
    },
    Header => {
        SubDirectory => { TagTable => 'Image::ExifTool::SigmaRaw::Header' },
    },
    Header4 => {
        SubDirectory => { TagTable => 'Image::ExifTool::SigmaRaw::Header4' },
    },
    HeaderExt => {
        SubDirectory => { TagTable => 'Image::ExifTool::SigmaRaw::HeaderExt' },
    },
    PROP => {
        Name => 'Properties',
        SubDirectory => { TagTable => 'Image::ExifTool::SigmaRaw::Properties' },
    },
    IMAG => {
        Name => 'PreviewImage',
        Groups => { 2 => 'Preview' },
        Binary => 1,
    },
    IMA2 => [
        {
            Name => 'PreviewImage',
            Condition => 'not $$self{IsJpgFromRaw}',
            Groups => { 2 => 'Preview' },
            Binary => 1,
        },
        {
            Name => 'JpgFromRaw',
            Groups => { 2 => 'Preview' },
            Binary => 1,
        },
    ]
);

# common X3F header structure
%Image::ExifTool::SigmaRaw::Header = (
    PROCESS_PROC => \&ProcessX3FHeader,
    FORMAT => 'int32u',
    NOTES => 'Information extracted from the header of an X3F file.',
    1 => {
        Name => 'FileVersion',
        ValueConv => '($val >> 16) . "." . ($val & 0xffff)',
    },
    2 => {
        Name => 'ImageUniqueID',
        # the serial number (with an extra leading "0") makes up
        # the first 8 digits of this UID,
        Format => 'undef[16]',
        ValueConv => 'unpack("H*", $val)',
    },
    6 => {
        Name => 'MarkBits',
        PrintConv => { BITMASK => { } },
    },
    7 => 'ImageWidth',
    8 => 'ImageHeight',
    9 => 'Rotation',
    10 => {
        Name => 'WhiteBalance',
        Format => 'string[32]',
    },
    18 => { #PH (DP2, FileVersion 2.3)
        Name => 'SceneCaptureType',
        Format => 'string[32]',
    },
);

# X3F version 4 header structure (ref PH)
%Image::ExifTool::SigmaRaw::Header4 = (
    PROCESS_PROC => \&Image::ExifTool::ProcessBinaryData,
    FORMAT => 'int32u',
    NOTES => 'Header information for version 4.0 or greater X3F.',
    1 => {
        Name => 'FileVersion',
        ValueConv => '($val >> 16) . "." . ($val & 0xffff)',
    },
    # 8 - undef[4]: 4 random ASCII characters
    10 => 'ImageWidth',
    11 => 'ImageHeight',
    12 => 'Rotation',
    # don't know what the rest of the header contains, but none of
    # these values change in any of my samples...
);

# extended header tags
%Image::ExifTool::SigmaRaw::HeaderExt = (
    GROUPS => { 2 => 'Camera' },
    FORMAT => 'float',
    NOTES => 'Extended header data found in version 2.1 and 2.2 files',
    0 => 'Unused',
    1 => { Name => 'ExposureAdjust',PrintConv => 'sprintf("%.1f",$val)' },
    2 => { Name => 'Contrast',      PrintConv => 'sprintf("%.1f",$val)' },
    3 => { Name => 'Shadow',        PrintConv => 'sprintf("%.1f",$val)' },
    4 => { Name => 'Highlight',     PrintConv => 'sprintf("%.1f",$val)' },
    5 => { Name => 'Saturation',    PrintConv => 'sprintf("%.1f",$val)' },
    6 => { Name => 'Sharpness',     PrintConv => 'sprintf("%.1f",$val)' },
    7 => { Name => 'RedAdjust',     PrintConv => 'sprintf("%.1f",$val)' },
    8 => { Name => 'GreenAdjust',   PrintConv => 'sprintf("%.1f",$val)' },
    9 => { Name => 'BlueAdjust',    PrintConv => 'sprintf("%.1f",$val)' },
   10 => { Name => 'X3FillLight',   PrintConv => 'sprintf("%.1f",$val)' },
);

# PROP tags
%Image::ExifTool::SigmaRaw::Properties = (
    PROCESS_PROC => \&ProcessX3FProperties,
    GROUPS => { 2 => 'Camera' },
    PRIORITY => 0,  # (because these aren't writable like the EXIF ones)
    AEMODE => {
        Name => 'MeteringMode',
        PrintConv => {
            8 => '8-segment',
            C => 'Center-weighted average',
            A => 'Average',
        },
    },
    AFAREA      => 'AFArea', # observed: CENTER_V
    AFINFOCUS   => 'AFInFocus', # observed: H
    AFMODE      => 'FocusMode',
    AP_DESC     => 'ApertureDisplayed',
    APERTURE => {
        Name => 'FNumber',
        Groups => { 2 => 'Image' },
        PrintConv => 'sprintf("%.1f",$val)',
    },
    BRACKET     => 'BracketShot',
    BURST       => 'BurstShot',
    CAMMANUF    => 'Make',
    CAMMODEL    => 'Model',
    CAMNAME     => 'CameraName',
    CAMSERIAL   => 'SerialNumber',
    CM_DESC     => 'SceneCaptureType', #PH (DP2)
    COLORSPACE  => 'ColorSpace', # observed: sRGB
    DRIVE => {
        Name => 'DriveMode',
        PrintConv => {
            SINGLE => 'Single Shot',
            MULTI  => 'Multi Shot',
            '2S'   => '2 s Timer',
            '10S'  => '10 s Timer',
            UP     => 'Mirror Up',
            AB     => 'Auto Bracket',
            OFF    => 'Off',
        },
    },
    EVAL_STATE  => 'EvalState', # observed: POST-EXPOSURE
    EXPCOMP => {
        Name => 'ExposureCompensation',
        Groups => { 2 => 'Image' },
        PrintConv => 'Image::ExifTool::Exif::PrintFraction($val)',
    },
    EXPNET => {
        Name => 'NetExposureCompensation',
        Groups => { 2 => 'Image' },
        PrintConv => 'Image::ExifTool::Exif::PrintFraction($val)',
    },
    EXPTIME => {
        Name => 'IntegrationTime',
        Groups => { 2 => 'Image' },
        ValueConv => '$val * 1e-6', # convert from usec
        PrintConv => 'Image::ExifTool::Exif::PrintExposureTime($val)',
    },
    FIRMVERS    => 'FirmwareVersion',
    FLASH => {
        Name => 'FlashMode',
        PrintConv => 'ucfirst(lc($val))',
    },
    FLASHEXPCOMP=> 'FlashExpComp',
    FLASHPOWER  => 'FlashPower',
    FLASHTTLMODE=> 'FlashTTLMode', # observed: ON
    FLASHTYPE   => 'FlashType', # observed: NONE
    FLENGTH => {
        Name => 'FocalLength',
        PrintConv => 'sprintf("%.1f mm",$val)',
    },
    FLEQ35MM => {
        Name => 'FocalLengthIn35mmFormat',
        PrintConv => 'sprintf("%.1f mm",$val)',
    },
    FOCUS => {
        Name => 'Focus',
        PrintConv => {
            AF => 'Auto-focus Locked',
           'NO LOCK' => "Auto-focus Didn't Lock",
            M => 'Manual',
        },
    },
    IMAGERBOARDID => 'ImagerBoardID',
    IMAGERTEMP  => {
        Name => 'SensorTemperature',
        PrintConv => '"$val C"',
    },
    IMAGEBOARDID=> 'ImageBoardID', #PH (DP2)
    ISO         => 'ISO',
    LENSARANGE  => 'LensApertureRange',
    LENSFRANGE  => 'LensFocalRange',
    LENSMODEL   => {
        Name => 'LensType',
        ValueConv => '$val =~ /^[0-9a-f]+$/i ? hex($val) : $val',
        ValueConvInv => '$val=~s/\.\d+$//; IsInt($val) ? sprintf("%x",$val) : $val', # (truncate decimal part)
        SeparateTable => 'Sigma LensType',
        PrintHex => 1,
        PrintConv => \%Image::ExifTool::Sigma::sigmaLensTypes,
    },
    PMODE => {
        Name => 'ExposureProgram',
        PrintConv => {
            P => 'Program',
            A => 'Aperture Priority',
            S => 'Shutter Priority',
            M => 'Manual',
        },
    },
    RESOLUTION => {
        Name => 'Quality',
        PrintConv => {
            LOW => 'Low',
            MED => 'Medium',
            HI  => 'High',
        },
    },
    SENSORID    => 'SensorID',
    SH_DESC     => 'ShutterSpeedDisplayed',
    SHUTTER => {
        Name => 'ExposureTime',
        Groups => { 2 => 'Image' },
        PrintConv => 'Image::ExifTool::Exif::PrintExposureTime($val)',
    },
    TIME => {
        Name => 'DateTimeOriginal',
        Groups => { 2 => 'Time' },
        Description => 'Date/Time Original',
        ValueConv => 'ConvertUnixTime($val)',
        PrintConv => '$self->ConvertDateTime($val)',
    },
    WB_DESC     => 'WhiteBalance',
    VERSION_BF  => 'VersionBF',
);

#------------------------------------------------------------------------------
# Extract null-terminated unicode string from list of characters
# Inputs: 0) ExifTool ref, 1) list ref, 2) position in list
# Returns: Converted string
sub ExtractUnicodeString($$$)
{
    my ($et, $chars, $pos) = @_;
    my $i;
    for ($i=$pos; $i<@$chars; ++$i) {
        last unless $$chars[$i];
    }
    my $buff = pack('v*', @$chars[$pos..$i-1]);
    return $et->Decode($buff, 'UCS2', 'II');
}

#------------------------------------------------------------------------------
# Process an X3F header
# Inputs: 0) ExifTool ref, 1) DirInfo ref, 2) tag table ref
# Returns: 1 on success
sub ProcessX3FHeader($$$)
{
    my ($et, $dirInfo, $tagTablePtr) = @_;
    my $dataPt = $$dirInfo{DataPt};
    my $hdrLen = $$dirInfo{DirLen};

    # process the static header structure first
    $et->ProcessBinaryData($dirInfo, $tagTablePtr);

    # process extended data if available
    if (length($$dataPt) - $hdrLen >= 160) {
        my $verbose = $et->Options('Verbose');
        if ($verbose) {
            $et->VerboseDir('X3F HeaderExt', 32);
            $et->VerboseDump($dataPt, Start => $hdrLen);
        }
        $tagTablePtr = GetTagTable('Image::ExifTool::SigmaRaw::HeaderExt');
        my @tags = unpack("x${hdrLen}C32", $$dataPt);
        my $i;
        my $unused = 0;
        for ($i=0; $i<32; ++$i) {
            $tags[$i] or ++$unused, next;
            $et->HandleTag($tagTablePtr, $tags[$i], undef,
                Index  => $i,
                DataPt => $dataPt,
                Start  => $hdrLen + 32 + $i * 4,
                Size   => 4,
            );
        }
        $et->VPrint(0, "$$et{INDENT}($unused entries unused)\n");
    }
    return 1;
}

#------------------------------------------------------------------------------
# Process an X3F properties
# Inputs: 0) ExifTool ref, 1) DirInfo ref, 2) tag table ref
# Returns: 1 on success
sub ProcessX3FProperties($$$)
{
    my ($et, $dirInfo, $tagTablePtr) = @_;
    my $dataPt = $$dirInfo{DataPt};
    my $size = length($$dataPt);
    my $verbose = $et->Options('Verbose');
    my $unknown = $et->Options('Unknown');

    unless ($size >= 24 and $$dataPt =~ /^SECp/) {
        $et->Warn('Bad properties header');
        return 0;
    }
    my ($entries, $fmt, $len) = unpack('x8V2x4V', $$dataPt);
    unless ($size >= 24 + 8 * $entries + $len) {
        $et->Warn('Truncated Property directory');
        return 0;
    }
    $verbose and $et->VerboseDir('Properties', $entries);
    $fmt == 0 or $et->Warn("Unsupported character format $fmt"), return 0;
    my $charPos = 24 + 8 * $entries;
    my @chars = unpack('v*',substr($$dataPt, $charPos, $len * 2));
    my $index;
    for ($index=0; $index<$entries; ++$index) {
        my ($namePos, $valPos) = unpack('V2',substr($$dataPt, $index*8 + 24, 8));
        if ($namePos >= @chars or $valPos >= @chars) {
            $et->Warn('Bad Property pointer');
            return 0;
        }
        my $tag = ExtractUnicodeString($et, \@chars, $namePos);
        my $val = ExtractUnicodeString($et, \@chars, $valPos);
        if (not $$tagTablePtr{$tag} and $unknown and $tag =~ /^\w+$/) {
            my $tagInfo = {
                Name => "SigmaRaw_$tag",
                Description => Image::ExifTool::MakeDescription('SigmaRaw', $tag),
                Unknown => 1,
                Writable => 0,  # can't write unknown tags
            };
            # add tag information to table
            AddTagToTable($tagTablePtr, $tag, $tagInfo);
        }

        $et->HandleTag($tagTablePtr, $tag, $val,
            Index => $index,
            DataPt => $dataPt,
            Start => $charPos + 2 * $valPos,
            Size => 2 * (length($val) + 1),
        );
    }
    return 1;
}

#------------------------------------------------------------------------------
# Write an X3F file
# Inputs: 0) ExifTool ref, 1) DirInfo ref (DirStart = directory offset)
# Returns: error string, undef on success, or -1 on write error
# Notes: Writes metadata to embedded JpgFromRaw image
sub WriteX3F($$)
{
    my ($et, $dirInfo) = @_;
    my $raf = $$dirInfo{RAF};
    my $outfile = $$dirInfo{OutFile};
    my ($hdr, $buff, $ver, $entries, $dir, $outPos, $index, $didContain, %order, @order);

    $raf->Seek($$dirInfo{DirStart}, 0) or return 'Error seeking to directory start';

    # read the X3F directory header (will be copied directly to output)
    $raf->Read($hdr, 12) == 12 or return 'Truncated X3F image';
    $hdr =~ /^SECd/ or return 'Bad section header';
    ($ver, $entries) = unpack('x4V2', $hdr);

    # do sanity check on number of entries in directory
    return 'Invalid X3F directory count' unless $entries > 2 and $entries < 20;
    # read the directory entries
    unless ($raf->Read($dir, $entries * 12) == $entries * 12) {
        return 'Truncated X3F directory';
    }
    # do a quick scan to determine the offset of the first data subsection,
    # and the order in which the actual data is stored in the file
    for ($index=0; $index<$entries; ++$index) {
        my $pos = $index * 12;
        my ($offset, $len, $tag) = unpack("x${pos}V2a4", $dir);
        # remember position of first data subsection
        $outPos = $offset if not defined $outPos or $outPos > $offset;
        # save the order of the data
        $order{BAD} = 1 if defined $order{$offset};
        $order{$offset} = $index;
    }
    # copy the file header up to the start of the first data subsection
    unless ($raf->Seek(0,0) and $raf->Read($buff, $outPos) == $outPos) {
        return 'Error reading X3F header';
    }
    Write($outfile, $buff) or return -1;

    # this is a bit tricky/unfortunate:  the current version of Sigma Photo Pro
    # (2022-10-18) is sensitive to the order of the data sections, and these may
    # differ from the order of their respective entries in the footer.  To patch
    # this, instead of looping through the footer sections in order, we process
    # them in the order of the offsets they contain, writing their referenced data
    # sequentially as we go.  This preserves both the order of the data sections
    # and the order of the footer entries.  (Note that the upcoming release of
    # Sigma Photo Pro will fix this issue at their end, but this patch will remain
    # to maintain backward compatibilty with older SPP versions.)
    if ($order{BAD}) {
        # (this could perhaps happen if any of the sections is ever zero-length)
        $et->Error('Double-referenced data in footer directory!', 1);
        @order = ( 0 .. $entries-1 );
    } else {
        @order = map $order{$_}, sort { $a <=> $b } keys %order;
    }

    # loop through footer directory, rewriting each section
    foreach $index (@order) {

        my $pos = $index * 12;
        my ($offset, $len, $tag) = unpack("x${pos}V2a4", $dir);
        $raf->Seek($offset, 0) or return 'Bad data offset';

        if ($tag eq 'IMA2' and $len > 28) {
            # check subsection header (28 bytes) to see if this is a JPEG preview image
            $raf->Read($buff, 28) == 28 or return 'Error reading PreviewImage header';
            Write($outfile, $buff) or return -1;
            $len -= 28;

            # only rewrite full-sized JpgFromRaw (version 2.0, type 2, format 18)
            if ($buff =~ /^SECi\0\0\x02\0\x02\0\0\0\x12\0\0\0/) {
                $raf->Read($buff, $len) == $len or return 'Error reading JpgFromRaw';
                if ($buff =~ /^\xff\xd8\xff\xe1/) { # does this preview contain EXIF?
                    # use same write directories as JPEG
                    $et->InitWriteDirs('JPEG');
                    # make sure we don't add APP0 JFIF because it would mess up our preview identification
                    delete $$et{ADD_DIRS}{APP0};
                    delete $$et{ADD_DIRS}{JFIF};
                    # rewrite the embedded JPEG in memory
                    my $newData;
                    my %jpegInfo = (
                        Parent  => 'X3F',
                        RAF     => new File::RandomAccess(\$buff),
                        OutFile => \$newData,
                    );
                    $$et{FILE_TYPE} = 'JPEG';
                    my $success = $et->WriteJPEG(\%jpegInfo);
                    $$et{FILE_TYPE} = 'X3F';
                    SetByteOrder('II');
                    return 'Error writing X3F JpgFromRaw' unless $success and $newData;
                    return -1 if $success < 0;
                    # (this shouldn't happen unless someone tries to delete the EXIF...)
                    return 'EXIF segment must come first in X3F JpgFromRaw' unless $newData =~ /^\xff\xd8\xff\xe1/;
                    # trim off any extra null bytes (since section length includes padding -- silly Sigma)
                    $newData =~ s/\0+$//;
                    # write new data if anything changed, otherwise copy old image
                    my $outPt = $$et{CHANGED} ? \$newData : \$buff;
                    Write($outfile, $$outPt) or return -1;
                    # set $len to the total subsection data length
                    $len = length($$outPt);
                    $didContain = 1;
                } else {
                    Write($outfile, $buff) or return -1;
                }
            } else {
                # copy original image data
                Image::ExifTool::CopyBlock($raf, $outfile, $len) or return 'Corrupted X3F image';
            }
            $len += 28;     # add back header length
        } else {
            # copy data for this subsection
            Image::ExifTool::CopyBlock($raf, $outfile, $len) or return 'Corrupted X3F directory';
        }
        # pad data to an even 4-byte boundary
        # (stored length includes padding! ref Sigma engineer Yuki Miyahara)
        if ($len & 0x03) {
            my $pad = 4 - ($len & 0x03);
            Write($outfile, "\0" x $pad) or return -1;
            $len += $pad;
        }
        # update footer entry with new offset/size
        substr($dir, $pos, 8) = pack('V2', $outPos, $len);
        $outPos += $len;
    }
    # warn if we couldn't add metadata to this image (should only be SD9 or SD10)
    $didContain or $et->Warn("Can't yet write SD9 or SD10 X3F images");
    # write out the directory and the directory pointer, and we are done
    Write($outfile, $hdr, $dir, pack('V', $outPos)) or return -1;
    return undef;
}

#------------------------------------------------------------------------------
# Process an X3F directory
# Inputs: 0) ExifTool ref, 1) DirInfo ref, 2) tag table ref
# Returns: error string or undef on success
sub ProcessX3FDirectory($$$)
{
    my ($et, $dirInfo, $tagTablePtr) = @_;
    my $raf = $$dirInfo{RAF};
    my $verbose = $et->Options('Verbose');

    $raf->Seek($$dirInfo{DirStart}, 0) or return 'Error seeking to directory start';

    # parse the X3F directory structure
    my ($buff, $ver, $entries, $index, $dir);
    $raf->Read($buff, 12) == 12 or return 'Truncated X3F image';
    $buff =~ /^SECd/ or return 'Bad section header';
    ($ver, $entries) = unpack('x4V2', $buff);
    $verbose and $et->VerboseDir('X3F Subsection', $entries);
    $raf->Read($dir, $entries * 12) == $entries * 12 or return 'Truncated X3F directory';
    for ($index=0; $index<$entries; ++$index) {
        my $pos = $index * 12;
        my ($offset, $len, $tag) = unpack("x${pos}V2a4", $dir);
        my $tagInfo = $et->GetTagInfo($tagTablePtr, $tag);
        if ($verbose) {
            $et->VPrint(0, "$$et{INDENT}$index) $tag Subsection ($len bytes):\n");
            if ($verbose > 2) {
                $raf->Seek($offset, 0) or return 'Error seeking';
                $raf->Read($buff, $len) == $len or return 'Truncated image';
                $et->VerboseDump(\$buff);
            }
        }
        next unless $tagInfo;
        $raf->Seek($offset, 0) or return "Error seeking for $$tagInfo{Name}";
        if  ($$tagInfo{Name} eq 'PreviewImage') {
            # check image header to see if this is a JPEG preview image
            $raf->Read($buff, 28) == 28 or return 'Error reading PreviewImage header';
            $offset += 28;
            $len -= 28;
            # ignore all image data but JPEG compressed (version 2.0, type 2, format 18)
            unless ($buff =~ /^SECi\0\0\x02\0\x02\0\0\0\x12\0\0\0/) {
                # do MD5 on non-preview data if requested
                if ($$et{ImageDataMD5} and substr($buff,8,1) ne "\x02") {
                    $et->ImageDataMD5($raf, $len, 'SigmaRaw IMAG');
                }
                next;
            }
            $raf->Read($buff, $len) == $len or return "Error reading PreviewImage data";
            # check fore EXIF segment, and extract this image as the JpgFromRaw
            if ($buff =~ /^\xff\xd8\xff\xe1/) {
                $$et{IsJpgFromRaw} = 1;
                $tagInfo = $et->GetTagInfo($tagTablePtr, $tag);
                delete $$et{IsJpgFromRaw};
            }
        } else {
            $raf->Read($buff, $len) == $len or return "Error reading $$tagInfo{Name} data";
        }
        my $subdir = $$tagInfo{SubDirectory};
        if ($subdir) {
            my %dirInfo = ( DataPt => \$buff );
            my $subTable = GetTagTable($$subdir{TagTable});
            $et->ProcessDirectory(\%dirInfo, $subTable);
        } else {
            # extract metadata from JpgFromRaw
            if ($$tagInfo{Name} eq 'JpgFromRaw') {
                my %dirInfo = (
                    Parent => 'X3F',
                    RAF    => new File::RandomAccess(\$buff),
                );
                $$et{BASE} += $offset;
                $et->ProcessJPEG(\%dirInfo);
                $$et{BASE} -= $offset;
                SetByteOrder('II');
            }
            $et->FoundTag($tagInfo, $buff);
        }
    }
    return undef;
}

#------------------------------------------------------------------------------
# Read/write information from a Sigma raw (X3F) image
# Inputs: 0) ExifTool ref, 1) DirInfo ref
# Returns: 1 on success, 0 if this wasn't a valid X3F image, or -1 on write error
sub ProcessX3F($$)
{
    my ($et, $dirInfo) = @_;
    my $outfile = $$dirInfo{OutFile};
    my $raf = $$dirInfo{RAF};
    my $warn = $outfile ? \&Image::ExifTool::Error : \&Image::ExifTool::Warn;
    my ($buff, $err, $hdrLen);

    return 0 unless $raf->Read($buff, 40) == 40;
    return 0 unless $buff =~ /^FOVb/;

    SetByteOrder('II');
    $et->SetFileType();

    # check version number
    my $ver = unpack('x4V',$buff);
    $ver = ($ver >> 16) . '.' . ($ver & 0xffff);
    if ($ver > 5) {
        &$warn($et, "Untested X3F version ($ver). Please submit sample for testing", 1);
    }
    # read version 2.1/2.2/2.3 extended header
    if ($ver > 2) {
        my ($extra, $buf2);
        if ($ver >= 4) {
            $hdrLen = 0x300;
            $extra = 0;
        } else {
            $hdrLen = $ver > 2.2 ? 104 : 72;    # SceneCaptureType string added in 2.3
            $extra = 160;                       # (extended header is 160 bytes)
        }
        my $more = $hdrLen - length($buff) + $extra;
        unless ($raf->Read($buf2, $more) == $more) {
            &$warn($et, 'Error reading X3F header');
            return 1;
        }
        $buff .= $buf2;
    }
    my ($widPos, $hdrType) = $ver < 4 ? (28, 'Header') : (40, 'Header4');
    # process header information
    my $tagTablePtr = GetTagTable('Image::ExifTool::SigmaRaw::Main');
    unless ($outfile) {
        $et->HandleTag($tagTablePtr, $hdrType, $buff,
            DataPt => \$buff,
            Size   => $hdrLen,
        );
    }
    # read the directory pointer
    $raf->Seek(-4, 2) or &$warn($et, 'Seek error'), return 1;
    unless ($raf->Read($buff, 4) == 4) {
        &$warn($et, 'Error reading X3F dir pointer');
        return 1;
    }
    my $offset = unpack('V', $buff);
    my %dirInfo = (
        RAF => $raf,
        DirStart => $offset,
    );
    if ($outfile) {
        $dirInfo{OutFile} = $outfile;
        $err = WriteX3F($et, \%dirInfo);
        return -1 if $err and $err eq '-1';
    } else {
        # process the X3F subsections
        $err = $et->ProcessDirectory(\%dirInfo, $tagTablePtr);
    }
    $err and &$warn($et, $err);
    return 1;
}

1;  # end

__END__