Image::ExifTool(3)

NAME
Image::ExifTool - Read and write meta information

SYNOPSIS
  use Image::ExifTool qw(:Public);

  # ---- Simple procedural usage ----

  # Get hash of meta information tag names/values from an image
  $info = ImageInfo('a.jpg');

  # ---- Object-oriented usage ----

  # Create a new Image::ExifTool object
  $exifTool = new Image::ExifTool;

  # Extract meta information from an image
  $exifTool->ExtractInfo($file, \%options);

  # Get list of tags in the order they were found in the file
  @tagList = $exifTool->GetFoundTags('File');

  # Get the value of a specified tag
  $value = $exifTool->GetValue($tag, $type);

  # Get a tag description
  $description = $exifTool->GetDescription($tag);

  # Get the group name associated with this tag
  $group = $exifTool->GetGroup($tag, $family);

  # Set a new value for a tag
  $exifTool->SetNewValue($tag, $newValue);

  # Write new meta information to a file
  $success = $exifTool->WriteInfo($srcfile, $dstfile);

  # ...plus a host of other useful methods...

DESCRIPTION
ExifTool provides an extensible set of perl modules to read and write meta information in image, audio and video files, including the maker note information of many digital cameras by various manufacturers such as Canon, Casio, FujiFilm, HP, JVC/Victor, Kodak, Leaf, Minolta/Konica-Minolta, Nikon, Olympus/Epson, Panasonic/Leica, Pentax/Asahi, Ricoh, Sanyo, Sigma/Foveon and Sony.

Below is a list of file types and meta information formats currently supported by ExifTool (r = read, w = write, c = create):

                File Types                 |    Meta Information
  ---------------------------------------  |  --------------------
  3FR   r       ITC   r       PPM   r/w    |  EXIF           r/w/c
  ACR   r       JNG   r/w     PPT   r      |  GPS            r/w/c
  AI    r       JP2   r/w     PS    r/w    |  IPTC           r/w/c
  AIFF  r       JPEG  r/w     PSD   r/w    |  XMP            r/w/c
  APE   r       K25   r       QTIF  r      |  MakerNotes     r/w/c
  ARW   r       KDC   r       RA    r      |  Photoshop IRB  r/w/c
  ASF   r       M4A   r       RAF   r/w    |  ICC Profile    r/w/c
  AVI   r       MEF   r/w     RAM   r      |  MIE            r/w/c
  BMP   r       MIE   r/w/c   RAW   r/w    |  JFIF           r/w/c
  BTF   r       MIFF  r       RIFF  r      |  Ducky APP12    r/w/c
  CR2   r/w     MNG   r/w     RM    r      |  CIFF           r/w
  CRW   r/w     MOS   r/w     SR2   r      |  AFCP           r/w
  CS1   r/w     MOV   r       SRF   r      |  JPEG 2000      r
  DCM   r       MP3   r       SVG   r      |  DICOM          r
  DCR   r       MP4   r       SWF   r      |  Flash          r
  DIVX  r       MPC   r       THM   r/w    |  FlashPix       r
  DNG   r/w     MPG   r       TIFF  r/w    |  QuickTime      r
  DOC   r       MRW   r/w     VRD   r/w/c  |  GeoTIFF        r
  EPS   r/w     NEF   r/w     WAV   r      |  PrintIM        r
  ERF   r/w     OGG   r       WDP   r/w    |  ID3            r
  FLAC  r       ORF   r/w     WMA   r      |  Kodak Meta     r
  FLV   r       PBM   r/w     WMV   r      |  Ricoh RMETA    r
  FPX   r       PDF   r/w     X3F   r      |  Picture Info   r
  GIF   r/w     PEF   r/w     XLS   r      |  Adobe APP14    r
  HDP   r/w     PGM   r/w     XMP   r/w/c  |  APE            r
  HTML  r       PICT  r                    |  Vorbis         r
  ICC   r/w/c   PNG   r/w                  |  (and more)

CONFIGURATION
User-defined tags can be added via the ExifTool configuration file, or by defining the %Image::ExifTool::UserDefined hash before calling any ExifTool functions. See "ExifTool_config" in the ExifTool distribution for more details. If necessary, the configuration feature can be disabled by setting the ExifTool "noConfig" flag before loading Image::ExifTool. For example:

    BEGIN { $Image::ExifTool::noConfig = 1 }
    use Image::ExifTool;

EXPORTS
Exports nothing by default, but "ImageInfo" and all static functions may be exported with the ":Public" export list.

METHODS

  new
Creates a new ExifTool object.

    $exifTool = new Image::ExifTool;

Note that ExifTool uses AUTOLOAD to load non-member methods, so any class using Image::ExifTool as a base class must define an AUTOLOAD which calls Image::ExifTool::DoAutoLoad(). ie)

    sub AUTOLOAD
    {
        Image::ExifTool::DoAutoLoad($AUTOLOAD, @_);
    }

  ImageInfo
Obtain meta information from image. This is the one step function for obtaining meta information from an image. Internally, "ImageInfo" calls "ExtractInfo" to extract the information, "GetInfo" to generate the information hash, and "GetTagList" for the returned tag list.

    # Return meta information for 2 tags only (procedural)
    $info = ImageInfo($filename, $tag1, $tag2);

    # Return information about an open image file (object-oriented)
    $info = $exifTool->ImageInfo(\*FILE);

    # Return information from image data in memory for specified tags
    %options = (PrintConv => 0);
    @tagList = qw(filename imagesize xmp:creator exif:* -ifd1:*);
    $info = ImageInfo(\$imageData, \@tagList, \%options);

    # Extract information from an embedded thumbnail image
    $info = ImageInfo('image.jpg', 'thumbnailimage');
    $thumbInfo = ImageInfo($$info{ThumbnailImage});

Inputs:
    "ImageInfo" is very flexible about the input arguments, and interprets them based on their type. It may be called with one or more arguments. The one required argument is either a SCALAR (the image file name), a file reference (a reference to the image file) or a SCALAR reference (a reference to the image in memory). Other arguments are optional. The order of the arguments is not significant, except that the first SCALAR is taken to be the file name unless a file reference or scalar reference comes earlier in the argument list.

    Below is an explanation of how the "ImageInfo" function arguments are interpreted:

    ExifTool ref
        "ImageInfo" may be called with an ExifTool object if desired. The advantage of using the object-oriented form is that the options may be set before calling "ImageInfo", and the object may be used afterward to access member functions. Must be the first argument if used.

    SCALAR
        The first scalar argument is taken to be the file name unless an earlier argument specified the image data via a file reference (file ref) or data reference (SCALAR ref). The remaining scalar arguments are names of tags for requested information. If no tags are specified, all possible information is extracted.

        Tag names are case-insensitive and may be prefixed by an optional group name followed by a colon. The group name may begin with a family number (ie. '1IPTC:Keywords'), to restrict matches to a specific family. A tag name of '*' may be used, thus allowing 'GROUP:*' to represent all tags in a specific group, or a group name of '*' may be used, in which case all available instances of the specified tag are returned regardless of the "Duplicates" setting (ie. '*:WhiteBalance'). And finally, a leading '-' indicates tags to be excluded (ie. '-IFD1:*').

        Note that keys in the returned information hash and elements of the returned tag list are not necessarily the same as these tag names -- group names are removed, the case may be changed, and an instance number may be added. For this reason it is best to use either the keys of the returned hash or the elements of the tag array when accessing the tag values.

        See Image::ExifTool::TagNames for a complete list of ExifTool tag names.

    File ref
        A reference to an open image file. If you use this method (or a SCALAR reference) to access information in an image, the FileName and Directory tags will not be returned. (Also, the FileSize and FileModifyDate tags will not be returned unless it is a plain file.) Image processing begins at the current file position, and on return the file position is unspecified. May be either a standard GLOB reference, or a reference to a File::RandomAccess object;

    SCALAR ref
        A reference to image data in memory.

    ARRAY ref
        Reference to a list of tag names. On entry, any elements in the list are added to the list of requested tags. Tags with names beginning with '-' are excluded. On return, this list is updated to contain an ordered list of tag keys for all extracted tags.

    HASH ref
        Reference to a hash containing the options settings. See "Options" documentation below for a list of available options. Options specified as arguments to "ImageInfo" take precedence over "Options" settings.

Return Values:
    "ImageInfo" returns a reference to a hash of tag key/value pairs. The tag keys are identifiers, which are similar to the tag names but may have an embedded instance number if multiple tags with the same name were extracted from the image. Many of the ExifTool functions require a tag key as an argument. Use "GetTagName [static]" to get the tag name for a given tag key. Note that the case of the tag names may not be the same as requested. Here is a simple example to print out the information returned by "ImageInfo":

        foreach (sort keys %$info) {
            print "$_ => $$info{$_}\n";
        }

    Values of the returned hash are usually simple scalars, but a scalar reference is used to indicate binary data and an array reference may be used to indicate a list. Lists of values are joined by commas into a single string if and only if the PrintConv option is enabled and the List option is disabled (which are the defaults). Note that binary values are not necessarily extracted unless specifically requested or the Binary option is set. If not extracted the value is a reference to a string of the form "Binary data ##### bytes".

    The code below gives an example of how to handle these return values, as well as illustrating the use of other ExifTool functions:

        use Image::ExifTool;
        my $exifTool = new Image::ExifTool;
        $exifTool->Options(Unknown => 1);
        my $info = $exifTool->ImageInfo('a.jpg');
        my $group = '';
        my $tag;
        foreach $tag ($exifTool->GetFoundTags('Group0')) {
            if ($group ne $exifTool->GetGroup($tag)) {
                $group = $exifTool->GetGroup($tag);
                print "---- $group ----\n";
            }
            my $val = $info->{$tag};
            if (ref $val eq 'SCALAR') {
                if ($$val =~ /^Binary data/) {
                    $val = "($$val)";
                } else {
                    my $len = length($$val);
                    $val = "(Binary data $len bytes)";
                }
            }
            printf("%-32s : %s\n", $exifTool->GetDescription($tag), $val);
        }

    As well as tags representing information extracted from the image, the following tags generated by ExifTool may be returned:

        ExifToolVersion - The ExifTool version number.

        Error - An error message if the image could not be processed.

        Warning - A warning message if problems were encountered while
                  processing the image.

  Options
Get/set ExifTool options. This function can be called to set the default options for an ExifTool object. Options set this way are in effect for all function calls but may be overridden by options passed as arguments to a specific function.

    # Exclude the 'OwnerName' tag from returned information
    $exifTool->Options(Exclude => 'OwnerName');

    # Only get information in EXIF or MakerNotes groups
    $exifTool->Options(Group0 => ['EXIF', 'MakerNotes']);

    # Ignore information from IFD1
    $exifTool->Options(Group1 => '-IFD1');

    # Sort by groups in family 2, and extract unknown tags
    $exifTool->Options(Sort => 'Group2', Unknown => 1);

    # Do not extract duplicate tag names
    $oldSetting = $exifTool->Options(Duplicates => 0);

    # Get current setting
    $isVerbose = $exifTool->Options('Verbose');

Inputs:
    0) ExifTool object reference.

    1) Option parameter name.

    2) [optional] Option parameter value (may be undef to clear option).

    3-N) [optional] Additional parameter/value pairs.

Option Parameters:
    Binary
        Flag to extract the value data for all binary tags. Tag values representing large binary data blocks (ie. ThumbnailImage) are not necessarily extracted unless this option is set or the tag is specifically requested by name. Default is 0.

    ByteOrder
        The byte order for newly created EXIF segments when writing. Note that if EXIF information already exists, the existing order is maintained. Valid values are 'MM', 'II' and undef. If ByteOrder is not defined (the default), then the maker note byte order is used (if they are being copied), otherwise big-endian ('MM') order is assumed. This can also be set via the ExifByteOrder tag, but the ByteOrder option takes precedence if both are set.

    Charset
        Character set for encoding character strings containing code points above U+007F. Valid values are:

          UTF8  - UTF-8 characters (the default)
          Latin - Windows Latin1 (cp1252)

        Note that this option affects some types of information when reading/writing the file and other types when getting/setting tag values, so it must be defined for both types of access.

    Compact
        Flag to write compact output. Default is 0. The XMP specification suggests that the data be padded with blanks to allow in-place editing. By setting this flag, 2kB is saved for files with XMP data.

    Composite
        Flag to calculate Composite tags automatically. Default is 1.

    Compress
        Flag to write new values in compressed format if possible. Has no effect unless Compress::Zlib is installed. Default is 0.

    CoordFormat
        Format for printing GPS coordinates. This is a printf format string with specifiers for degrees, minutes and seconds in that order, however minutes and seconds may be omitted. For example, the following table gives the output for the same coordinate using various formats:

                CoordFormat          Example Output
            -------------------    ------------------
            q{%d deg %d' %.2f"}    54 deg 59' 22.80"   (the default)
            q{%d deg %.4f min}     54 deg 59.3800 min
            q{%.6f degrees}        54.989667 degrees

    DateFormat
        Format for printing date/time values. See "strftime" in the POSIX package for details about the format string. The default is similar to a format of "%Y:%m:%d %H:%M:%S". If date can not be converted, value is left unchanged unless the StrictDate option is set. Timezones are ignored.

    Duplicates
        Flag to preserve values of duplicate tags (instead of overwriting existing value). Default is 1.

    Exclude
        Exclude specified tags from tags extracted from an image. The option value is either a tag name or reference to a list of tag names to exclude. The case of tag names is not significant. This option is ignored for specifically requested tags. Tags may also be excluded by preceeding their name with a '-' in the arguments to "ImageInfo".

    FastScan
        Flag to increase speed of extracting information from JPEG images. With this option set, ExifTool will not scan to the end of a JPEG image to check for an AFCP, CanonVRD, FotoStation, PhotoMechanic, MIE or PreviewImage trailer. Also, when combined with the ScanForXMP option, prevents scanning for XMP in recognized file types. Default 0.

    FixBase
        Fix maker notes base offset. A common problem with image editing software is that offsets in the maker notes are not adjusted properly when the file is modified. This may cause the wrong values to be extracted for some maker note entries when reading the edited file. FixBase specifies an integer value to be added to the maker notes base offset. It may also be set to the empty string ('') for ExifTool will take its best guess at the correct base, or undef (the default) for no base adjustment.

    Group#
        Extract tags only for specified groups in family # (Group0 assumed if # not given). The option value may be a single group name or a reference to a list of groups. Case is significant in group names. Specify a group to be excluded by preceding group name with a '-'. See "GetAllGroups [static]" for a list of available groups.

    HtmlDump
        Dump information in hex to dynamic HTML web page. The value may be 0-3 for increasingly larger limits on the maximum block size. Default is 0. Output goes to the file specified by the TextOut option (\*STDOUT by default).

    HtmlDumpBase
        Specifies base for HTML dump offsets. If not defined, the EXIF/TIFF base offset is used. Set to 0 for absolute offsets. Default is undef.

    IgnoreMinorErrors
        Flag to ignore minor errors. Causes minor errors to be downgraded to warnings, and minor warnings to be ignored. This option is provided mainly to allow writing of files when minor errors occur, but also allows thumbnail and preview images to be extracted even if they don't have a recognizable header. Minor errors/warnings are denoted by '[minor]' at the start of the message.

    List
        Flag to extract lists of PrintConv values into arrays instead of concatenating them into comma-separated strings. Default is 0.

    MakerNotes
        Option to extract MakerNotes and other writable subdirectories (such as PrintIM) as a data block. Normally when the MakerNotes are extracted they are rebuilt to include data outside the boundaries of the original maker note data block, but a value of 2 disables this feature. Possible values are:

          0 - Do not extract writable subdirectories [default]
          1 - Extract and rebuild maker notes into self-contained block
          2 - Extract without rebuilding maker notes

    MissingTagValue
        Value for missing tags in expressions evaluated by "SetNewValuesFromFile". If not set, a minor error is issued for missing values, or the value is set to '' if "IgnoreMinorErrors" is set. Default is undef.

    PrintConv
        Flag to enable automatic print conversion. Also enables inverse print conversion for writing. Default is 1.

    ScanForXMP
        Flag for scan all files (even unrecognized formats) for XMP information unless XMP was already found in the file. When combined with the FastScan option, only unrecognized file types are scanned for XMP. Default is 0.

    Sort
        Specifies order to sort tags in returned list:

          Alpha  - Sort alphabetically
          File   - Sort in order that tags were found in the file
          Group# - Sort by tag group, where # is the group family
                   number.  If # is not specified, Group0 is assumed.
                   See GetGroup for a list of groups.
          Input  - Sort in same order as input tag arguments (default)

    StrictDate
        Flag to return undefined value for any date which can't be converted when the DateFormat option is used. Default is 0.

    TextOut
        Output file reference for Verbose and HtmlDump options. Default is \*STDOUT.

    Unknown
        Flag to get the values of unknown tags. If set to 1, unknown tags are extracted from EXIF (or other tagged-format) directories. If set to 2, unknown tags are also extracted from binary data blocks. Default is 0.

    Verbose
        Print verbose messages to file specified by TextOut option. Value may be from 0 to 5 for increasingly verbose messages. Default is 0. With the verbose option set, messages are printed to the console as the file is parsed. Level 1 prints the tag names and raw values. Level 2 adds more details about the tags. Level 3 adds a hex dump of the tag data, but with limits on the number of bytes dumped. Levels 4 and 5 remove the dump limit on tag values and JPEG segment data respectively.

Return Values:
    The original value of the last specified parameter.

  ClearOptions
Reset all options to their default values.

    $exifTool->ClearOptions();

Inputs:
    0) ExifTool object reference

Return Values:
    (none)

  ExtractInfo
Extract all meta information from an image.

    $success = $exifTool->ExtractInfo('image.jpg', \%options);

Inputs:
    "ExtractInfo" takes exactly the same arguments as "ImageInfo". The only difference is that a list of tag keys is not returned if an ARRAY reference is given. The following options are effective in the call to "ExtractInfo":

    Binary, Charset, Composite, FastScan, FixBase, HtmlDump, HtmlDumpBase, IgnoreMinorErrors, MakerNotes, ScanForXMP, TextOut, Unknown and Verbose.

Return Value:
    1 if image was valid, 0 otherwise (and 'Error' tag set).

  GetInfo
"GetInfo" is called to return meta information after it has been extracted from the image by a previous call to "ExtractInfo" or "ImageInfo". This function may be called repeatedly after a single call to "ExtractInfo" or "ImageInfo".

    # Get image width and hieght only
    $info = $exifTool->GetInfo('ImageWidth', 'ImageHeight');

    # Get information for all tags in list (list updated with tags found)
    $info = $exifTool->GetInfo(\@ioTagList);

    # Get all information in Author or Location groups
    $info = $exifTool->GetInfo({Group2 => ['Author', 'Location']});

Inputs:
    Inputs are the same as "ExtractInfo" and "ImageInfo" except that an image can not be specified. Options in effect are:

    Charset, CoordFormat, DateFormat, Duplicates, Exclude, Group#, List, StrictDate, PrintConv (and Sort if a tag list reference is given).

Return Value:
    Reference to information hash, the same as with "ImageInfo".

  WriteInfo
Write meta information to a file. The specified source file is rewritten to the same-type destination file with new information as specified by previous calls to "SetNewValue". The necessary segments and/or directories are created in the destination file as required to store the specified information. May be called repeatedly to write the same information to additional files without the need to call "SetNewValue" again.

    # add information to a source file, writing output to new file
    $exifTool->WriteInfo($srcfile, $dstfile);

    # create XMP data file from scratch
    $exifTool->WriteInfo(undef, $dstfile, 'XMP');

    # edit file in place (you do have backups, right?)
    $exifTool->WriteInfo($srcfile);

Inputs:
    0) ExifTool object reference

    1) Source file name, file reference, scalar reference, or undef to create a file from scratch

    2) [optional] Destination file name, file reference, scalar reference, or undef to edit in place

    3) [optional] Destination file type

Return Value:
    1 if file was written OK, 2 if file was written but no changes made, 0 on file write error.

    If an error code is returned, an Error tag is set and GetValue('Error') can be called to obtain the error description. A Warning tag may be set even if this routine is successful.

        $errorMessage = $exifTool->GetValue('Error');
        $warningMessage = $exifTool->GetValue('Warning');

Notes:
    The source file name may be undefined to create a file from scratch (currently only XMP, ICC and MIE files can be created in this way). If undefined, the destination file type is required unless the type can be determined from the destination file name.

    If a destination file name is given, the specified file must not exist because an existing destination file will not be overwritten. The destination file name may be undefined to edit the source file in place (make sure you have backups!). In this case, a temporary file is created and renamed to replace the source file if no errors occurred while writing.

    The destination file type is only used if the source file is undefined.

  CombineInfo
Combine information from more than one information hash into a single hash.

    $info = $exifTool->CombineInfo($info1, $info2, $info3);

Inputs:
    0) ExifTool object reference

    1-N) Information hash references

If the Duplicates option is disabled and duplicate tags exist, the order of the hashes is significant. In this case, the value used is the first value found as the hashes are scanned in order of input. The Duplicates option is the only option that is in effect for this function.

  GetTagList
Get a sorted list of tags from the specified information hash or tag list.

    @tags = $exifTool->GetTagList($info, 'Group0');

Inputs:
    0) ExifTool object reference,

    1) [optional] Information hash reference or tag list reference,

    2) [optional] Sort order ('File', 'Input', 'Alpha' or 'Group#').

    If the information hash or tag list reference is not provided, then the list of found tags from the last call to "ImageInfo", "ExtractInfo" or "GetInfo" is used instead, and the result is the same as if "GetFoundTags" was called. If sort order is not specified, the sort order is taken from the current options settings.

Return Values:
    A list of tags in the specified order.

  GetFoundTags
Get list of found tags in specified sort order. The found tags are the tags for the information obtained from the most recent call to "ImageInfo", "ExtractInfo" or "GetInfo" for this object.

    @tags = $exifTool->GetFoundTags('File');

Inputs:
    0) ExifTool object reference

    1) [optional] Sort order ('File', 'Input', 'Alpha' or 'Group#')

    If sort order is not specified, the sort order from the ExifTool options is used.

Return Values:
    A list of tag keys in the specified order.

  GetRequestedTags
Get list of requested tags. These are the tags that were specified in the arguments of the most recent call to "ImageInfo", "ExtractInfo" or "GetInfo", including tags specified via a tag list reference. Shortcut tags are expanded in the list.

    @tags = $exifTool->GetRequestedTags();

Inputs:
    (none)

Return Values:
    List of requested tag keys in the same order that the tags were specified. Note that this list will be empty if tags were not specifically requested (ie. If extracting all tags).

  GetValue
Get the value of a specified tag. The returned value is either the human-readable (PrintConv) value, the converted machine-readable (ValueConv) value, or the original raw (Raw) value. If the value type is not specified, the PrintConv value is returned if the PrintConv option is set, otherwise the ValueConv value is returned. The PrintConv values are same as the values returned by "ImageInfo" and "GetInfo" in the tag/value hash unless the PrintConv option is disabled.

Tags which represent lists of multiple values (as may happen with 'Keywords' for example) are handled specially. In scalar context, the returned PrintConv value for these tags is either a comma-separated string of values or a list reference (depending on the List option setting), and the ValueConv value is always a list reference. But in list context, "GetValue" always returns the list itself.

    # PrintConv example
    my $val = $exifTool->GetValue($tag);
    if (ref $val eq 'SCALAR') {
        print "$tag = (unprintable value)\n";
    } else {
        print "$tag = $val\n";
    }

    # ValueConv examples
    my $val = $exifTool->GetValue($tag, 'ValueConv');
    if (ref $val eq 'ARRAY') {
        print "$tag is a list of values\n";
    } elsif (ref $val eq 'SCALAR') {
        print "$tag represents binary data\n";
    } else {
        print "$tag is a simple scalar\n";
    }

    my @keywords = $exifTool->GetValue('Keywords', 'ValueConv');

Inputs:
    0) ExifTool object reference

    1) Tag key

    2) [optional] Value type, 'PrintConv', 'ValueConv', 'Both' or 'Raw'

    The default value type is 'PrintConv' if the PrintConv option is set, otherwise the default is 'ValueConv'. A value type of 'Both' returns both ValueConv and PrintConv values as a list.

Return Values:
    The value of the specified tag. If the tag represents a list of values and the List option is disabled then PrintConv returns a comma separated string of values, otherwise a reference to the list is returned in scalar context. The list itself is returned in list context. Values may also be scalar references to binary data.

    Note: It is possible for "GetValue" to return an undefined ValueConv or PrintConv value (or an empty list in list context) even if the tag exists, since it is possible for these conversions to yield undefined values.

  SetNewValue
Set the new value for a tag. The routine may be called multiple times to set the values of many tags before using "WriteInfo" to write the new values to an image.

For list-type tags (like Keywords), either call repeatedly with the same tag name for each value, or call with a reference to the list of values.

    # set a new value for a tag (errors go to STDERR)
    $success = $exifTool->SetNewValue($tag, $value);

    # set a new value and capture any error message
    ($success, $errStr) = $exifTool->SetNewValue($tag, $value);

    # delete information for specified tag if it exists in image
    # (also resets AddValue and DelValue options for this tag)
    $exifTool->SetNewValue($tag);

    # reset all values from previous calls to SetNewValue()
    $exifTool->SetNewValue();

    # delete a specific keyword
    $exifTool->SetNewValue('Keywords', $word, DelValue => 1);

    # write a list of keywords
    $exifTool->SetNewValue('Keywords', ['word1','word2']);

    # add a keyword without replacing existing keywords
    $exifTool->SetNewValue(Keywords => $word, AddValue => 1);

    # set a tag in a specific group
    $exifTool->SetNewValue(Headline => $val, Group => 'XMP');
    $exifTool->SetNewValue('XMP:Headline' => $val);  # equivalent

    # shift original date/time back by 1 hour
    $exifTool->SetNewValue(DateTimeOriginal => '1:00', Shift => -1);

    # delete all but EXIF tags
    $exifTool->SetNewValue('*');  # delete all...
    $exifTool->SetNewValue('EXIF:*', undef, Replace => 2); # ...but EXIF

Inputs:
    0) ExifTool object reference

    1) [optional] Tag key or tag name, or undef to clear all new values. A tag name of '*' can be used when deleting tags to delete all tags, or all tags in a specified group. The tag name may be prefixed by group name, separated by a colon (ie. 'GROUP:TAG'), which is equivalent to using a 'Group' option argument.

    2) [optional] New value for tag. Undefined to delete tag from file. May be a scalar, scalar reference, or list reference to set a list of values.

    3-N) [optional] SetNewValue options hash entries (see below)

SetNewValue Options:
    Type
        The type of value being set. Valid values are PrintConv, ValueConv or Raw. Default is PrintConv if the "PrintConv" Option is set, otherwise ValueConv.

    AddValue
        Specifies that the value be added to an existing list rather than replacing the list. Valid values are 0 or 1. Default is 0.

    DelValue
        Delete the existing tag if it has the specified value. Valid values are 0 or 1. Default is 0.

    Group
        Specifies group name where tag should be written. If not specified, tag is written to highest priority group as specified by "SetNewGroups". Any family 0 or 1 group name may be used. Case is not significant.

    NoShortcut
        Disables default behaviour of looking up tag in shortcuts if not found otherwise.

    Protected
        Bit mask for tag protection levels to write. Bit 0x01 allows writing of 'unsafe' tags (ie. tags not copied automatically via "SetNewValuesFromFile"). Bit 0x02 allows writing of 'protected' tags, and should only be used internally by ExifTool. See Image::ExifTool::TagNames, for a list of tag names indicating 'unsafe' and 'protected' tags. Default is 0.

    Replace
        Flag to replace the previous new value for this tag (ie. replace the value set in a previous call to "SetNewValue"). Valid values are 0 (don't replace), 1 (replace with specified new value) or 2 (reset previous new value only).

    Shift
        Shift the tag by the specified value. Currently only date/time tags can be shifted. Undefined for no shift, 1 for a positive shift, or -1 for a negative shift. If 0, the shift is applied only if the tag is shiftable, and the shift is positive if AddValue is set, or negative if DelValue is set. Default is undef. See Image::ExifTool::Shift.pl for more information.

Return Values:
    In scalar context, returns the number of tags set and error messages are printed to STDERR. In list context, returns the number of tags set and the error string.

  SetNewValuesFromFile
A very powerful routine that sets new values for tags from information found in a specified file.

    # set new values from all information in a file...
    my $info = $exifTool->SetNewValuesFromFile($srcFile);
    # ...then write these values to another image
    my $result = $exifTool->WriteInfo($file2, $outFile);

    # set all new values, preserving original groups
    $exifTool->SetNewValuesFromFile($srcFile, '*:*');

    # set specific information
    $exifTool->SetNewValuesFromFile($srcFile, @tags);

    # set new value from a different tag in specific group
    $exifTool->SetNewValuesFromFile($fp, 'IPTC:Keywords>XMP-dc:Subject');

    # add all IPTC keywords to XMP subject list
    $exifTool->SetNewValuesFromFile($fp, 'IPTC:Keywords+>XMP-dc:Subject');

    # set new value from an expression involving other tags
    $exifTool->SetNewValuesFromFile($file,
        'Comment<ISO=$ISO Aperture=$aperture Exposure=$shutterSpeed');

Inputs:
    0) ExifTool object reference

    1) File name, file reference, or scalar reference

    2-N) [optional] List of tag names to set. All writable tags are set if none are specified. The tag names are not case sensitive, and may be prefixed by an optional family 0 or 1 group name, separated by a colon (ie. 'exif:iso'). A leading '-' indicates tags to be excluded (ie. '-comment'). An asterisk ('*') may be used for the tag name, and is useful when a group is specified to set all tags from a group (ie. 'XMP:*'). A special feature allows tag names of the form 'SRCTAG>DSTTAG' (or 'DSTTAG<SRCTAG') to be specified to copy information to a tag with a different name or a specified group. Both 'SRCTAG' and 'DSTTAG' may use '*' and/or be prefixed by a group name (ie. 'modifyDate>fileModifyDate' or '*>xmp:*'). Copied tags may also be added or deleted from a list with arguments of the form 'SRCTAG+>DSTTAG' or 'SRCTAG->DSTTAG'. Tags are evaluated in order, so exclusions apply only to tags included earlier in the list. An extension of this feature allows the tag value to be set from an expression containing tag names with leading '$' symbols (ie. 'Comment<Filename: $filename'). Braces '{}' may be used around the tag name to separate it from subsequent text, and a '$$' is used to to represent a '$' symbol. (The behaviour for missing tags in expressions is defined by the "MissingTagValue" option.)

    By default, this routine will commute information between same-named tags in different groups, allowing information to be translated between images with different formats. This behaviour may be modified by specifying a group name for extracted tags (even if '*' is used as a group name), in which case the information is written to the original group, unless redirected to a different group. (For example, a tag name of '*:*' may be specified to copy all information while preserving the original groups.)

Return Values:
    A hash of information that was set successfully. May include Warning or Error entries if there were problems reading the input file.

Notes:
    The PrintConv option applies to this routine, but it normally should be left on to provide more reliable transfer of information between groups.

    If a preview image exists, it is not copied. The preview image must be transferred separately if desired.

    When simply copying all information between files of the same type, it is usually desirable to preserve the original groups by specifying '*:*' for the tags to set.

  GetNewValues
Get list of new Raw values for the specified tag. These are the values that will be written to file. Only tags which support a 'List' may return more than one value.

    $rawVal = $exifTool->GetNewValues($tag);

    @rawVals = $exifTool->GetNewValues($tag);

Inputs:
    0) ExifTool object reference

    1) Tag key or tag name

Return Values:
    List of new Raw tag values. The list may be empty if the tag is being deleted (ie. if SetNewValue was called without a value).

  CountNewValues
Return the total number of new values set.

    $numSet = $exifTool->CountNewValues();
    ($numSet, $numPseudo) = $exifTool->CountNewValues();

Inputs:
    0) ExifTool object reference

Return Values:
    In scalar context, returns the total number of tags with new values set. In list context, also returns the number of "pseudo" tag values which have been set. "Pseudo" tags are tags like FileName and FileModifyDate which are not contained within the file and can be changed without rewriting the file.

  SaveNewValues
Save state of new values to be later restored by "RestoreNewValues".

    $exifTool->SaveNewValues();         # save state of new values
    $exifTool->SetNewValue(ISO => 100); # set new value for ISO
    $exifTool->WriteInfo($src, $dst1);  # write ISO + previous new values
    $exifTool->RestoreNewValues();      # restore previous new values
    $exifTool->WriteInfo($src, $dst2);  # write previous new values only

Inputs:
    0) ExifTool object reference

Return Value:
    None.

  RestoreNewValues
Restore new values to the settings that existed when "SaveNewValues" was last called. May be called repeatedly after a single call to "SaveNewValues". See "SaveNewValues" above for an example.

Inputs:
    0) ExifTool object reference

Return Value:
    None.

  SetFileModifyDate
Set the file modification time from the new value of the FileModifyDate tag.

    $result = $exifTool->SetFileModifyDate($file);

Inputs:
    0) ExifTool object reference

    1) File name

    2) [optional] Base time if applying shift (days before $^T)

Return Value:
    1 if the time was changed, 0 if nothing was done, or -1 if there was an error setting the time.

  SetFileName
Set the file name and directory. If not specified, the new file name is derived from the new values of the FileName and Directory tags. If the FileName tag contains a '/', then the file is renamed into a new directory. If FileName ends with '/', then it is taken as a directory name and the file is moved into the new directory. The new value for the Directory tag takes precedence over any directory specified in FileName.

    $result = $exifTool->SetFileName($file);
    $result = $exifTool->SetFileName($file, $newName);

Inputs:
    0) ExifTool object reference

    1) Current file name

    2) [optional] New file name

Return Value:
    1 if the file name or directory was changed, 0 if nothing was done, or -1 if there was an error renaming the file.

Notes:
    Will not overwrite existing files. New directories are created as necessary.

  SetNewGroups
Set the order of the preferred groups when adding new information. In subsequent calls to "SetNewValue", new information will be created in the first valid group of this list. This has an impact only if the group is not specified when calling "SetNewValue" and if the tag name exists in more than one group. The default order is EXIF, IPTC, XMP then MakerNotes. Any family 0 group name may be used. Case is not significant.

    $exifTool->SetNewGroups('XMP','EXIF','IPTC');

Inputs:
    0) ExifTool object reference

    1-N) Groups in order of priority. If no groups are specified, the priorities are reset to the defaults.

Return Value:
    None.

  GetNewGroups
Get current group priority list.

    @groups = $exifTool->GetNewGroups();

Inputs:
    0) ExifTool object reference

Return Values:
    List of group names in order of write priority. Highest priority first.

  GetTagID
Get the ID for the specified tag. The ID is the IFD tag number in EXIF information, the property name in XMP information, or the data offset in a binary data block. For some tags, such as Composite tags where there is no ID, an empty string is returned.

    $id = $exifTool->GetTagID($tag);

Inputs:
    0) ExifTool object reference

    1) Tag key

Return Values:
    Tag ID or '' of there is no ID for this tag.

  GetDescription
Get description for specified tag. This function will always return a defined value. In the case where the description doesn't exist, the tag name is returned.

Inputs:
    0) ExifTool object reference

    1) Tag key

Return Values:
    A description for the specified tag.

  GetGroup
Get group name for specified tag.

    $group = $exifTool->GetGroup($tag, 0);

Inputs:
    0) ExifTool object reference

    1) Tag key

    2) [optional] Group family number

Return Values:
    Group name (or 'Other' if tag has no group). If no group family is specified, "GetGroup" returns the name of the group in family 0 when called in scalar context, or the names of groups for all families in list context. See "GetAllGroups [static]" for a list of groups in each famly.

  GetGroups
Get list of group names for specified information.

    @groups = $exifTool->GetGroups($info, 2);

Inputs:
    0) ExifTool object reference

    1) [optional] Info hash ref (default is all extracted info)

    2) [optional] Group family number (default 0)

Return Values:
    List of group names in alphabetical order. If information hash is not specified, the group names are returned for all extracted information.

  BuildCompositeTags
Builds composite tags from required tags. The composite tags are convenience tags which are derived from the values of other tags. This routine is called automatically by "ImageInfo" and "ExtractInfo" if the Composite option is set.

Inputs:
    0) ExifTool object reference

Return Values:
    (none)

Notes:
    Tag values are calculated in alphabetical order unless a tag Require's or Desire's another composite tag, in which case the calculation is deferred until after the other tag is calculated. Composite tags may need to read data from the image for their value to be determined, so for these "BuildCompositeTags" must be called while the image is available. This is only a problem if "ImageInfo" is called with a filename (as opposed to a file reference or scalar reference) since in this case the file is closed before "ImageInfo" returns. However if you enable the Composite option, "BuildCompositeTags" is called from within "ImageInfo" before the file is closed.

  GetTagName [static]
Get name of tag from tag key. This is a convenience function that strips the embedded instance number, if it exists, from the tag key.

Note: "static" in the heading above indicates that the function does not require an ExifTool object reference as the first argument. All functions documented below are also static.

    $tagName = Image::ExifTool::GetTagName($tag);

Inputs:
    0) Tag key

Return Value:
    Tag name. This is the same as the tag key but has the instance number removed.

  GetShortcuts [static]
Get a list of shortcut tags.

Inputs:
    (none)

Return Values:
    List of shortcut tags (as defined in Image::ExifTool::Shortcuts).

  GetAllTags [static]
Get list of all available tag names.

    @tagList = Image::ExifTool::GetAllTags($group);

Inputs:
    0) [optional] Group name

Return Values:
    A list of all available tags in alphabetical order, or all tags in specified group. The group name is case insensitive, and any group in any family may be used except for EXIF family 1 groups (ie. the specific IFD).

  GetWritableTags [static]
Get list of all writable tag names.

    @tagList = Image::ExifTool::GetWritableTags($group);

Inputs:
    0) [optional] Group name

Return Values:
    A list of all writable tags in alphabetical order. These are the tags for which values may be set through "SetNewValue". If a group name is given, returns only writable tags in specified group. The group name is case insensitive, and any group in any family may be used except for EXIF family 1 groups (ie. the specific IFD).

  GetAllGroups [static]
Get list of all group names in specified family.

    @groupList = Image::ExifTool::GetAllGroups($family);

Inputs:
    0) Group family number (0-2)

Return Values:
    A list of all groups in the specified family in alphabetical order.

Three families of groups are currently defined: 0, 1 and 2. Families 0 and 1 are based on the file structure, and family 2 classifies information based on the logical category to which the information refers.

Families 0 and 1 are similar except that family 1 is more specific, and sub-divides the EXIF, MakerNotes, XMP and ICC_Profile groups to give more detail about the specific location where the information was found. The EXIF group is split up based on the specific IFD (Image File Directory), the MakerNotes group is divided into groups for each manufacturer, and the XMP group is separated based on the XMP namespace prefix. Note that only common XMP namespaces are listed below but additional namespaces may be present in some XMP data. Also note that the 'XMP-xmp...' group names may appear in the older form 'XMP-xap...' since these names evolved as the XMP standard was developed. The ICC_Profile group is broken down to give information about the specific ICC_Profile tag from which multiple values were extracted. As well, information extracted from the ICC_Profile header is separated into the ICC-header group.

Here is a complete list of groups for each family:

Family 0 (Information Type):
    AFCP, AIFF, APE, APP12, APP13, APP14, APP15, APP5, APP6, APP8, ASF, BMP, CanonVRD, Composite, DICOM, DNG, Ducky, EXIF, ExifTool, FLAC, File, Flash, FlashPix, FotoStation, GeoTiff, HTML, ICC_Profile, ID3, IPTC, ITC, JFIF, JPEG, Jpeg2000, Leaf, MIE, MIFF, MNG, MPC, MPEG, MakerNotes, Meta, PDF, PICT, PNG, PhotoMechanic, Photoshop, PostScript, PrintIM, QuickTime, RAF, RIFF, Real, SVG, SigmaRaw, Vorbis, XMP

Family 1 (Specific Location):
    AFCP, AIFF, APE, ASF, Adobe, AdobeCM, BMP, Canon, CanonCustom, CanonRaw, CanonVRD, Casio, Composite, DICOM, DNG, Ducky, EPPIM, ExifIFD, ExifTool, FLAC, File, Flash, FlashPix, FotoStation, FujiFilm, GPS, GeoTiff, GlobParamIFD, GraphConv, HP, HTML, HTML-dc, HTML-ncc, HTML-prod, HTML-vw96, HTTP-equiv, ICC-chrm, ICC-clrt, ICC-header, ICC-meas, ICC-view, ICC_Profile, ID3, ID3v1, ID3v2_2, ID3v2_3, ID3v2_4, IFD0, IFD1, IPTC, ITC, InteropIFD, JFIF, JPEG, JVC, Jpeg2000, Kodak, KodakBordersIFD, KodakEffectsIFD, KodakIFD, KyoceraRaw, Leaf, LeafSubIFD, Leica, MAC, MIE-Audio, MIE-Camera, MIE-Doc, MIE-Extender, MIE-Flash, MIE-GPS, MIE-Geo, MIE-Image, MIE-Lens, MIE-Main, MIE-MakerNotes, MIE-Meta, MIE-Orient, MIE-Preview, MIE-Test, MIE-Thumbnail, MIE-UTM, MIE-Unknown, MIE-Video, MIFF, MNG, MPC, MPEG, MakerNotes, MakerUnknown, MetaIFD, Minolta, MinoltaRaw, Nikon, NikonCapture, NikonPreview, NikonScan, Olympus, PDF, PICT, PNG, Panasonic, Pentax, PhotoMechanic, Photoshop, PictureInfo, PostScript, PrintIM, QuickTime, RAF, RAF2, RIFF, RMETA, Real, Real-CONT, Real-MDPR, Real-PROP, Real-RA3, Real-RA4, Real-RA5, Real-RJMD, Ricoh, SPIFF, SR2, SR2DataIFD, SR2SubIFD, SRF#, SVG, Sanyo, Sigma, SigmaRaw, Sony, SubIFD, Track#, Vorbis, XMP, XMP-DICOM, XMP-PixelLive, XMP-aux, XMP-cc, XMP-crs, XMP-dc, XMP-dex, XMP-exif, XMP-iptcCore, XMP-lr, XMP-mediapro, XMP-microsoft, XMP-pdf, XMP-photomech, XMP-photoshop, XMP-tiff, XMP-xmp, XMP-xmpBJ, XMP-xmpDM, XMP-xmpMM, XMP-xmpPLUS, XMP-xmpRights, XMP-xmpTPg

Family 2 (Category):
    Audio, Author, Camera, Document, ExifTool, Image, Location, Other, Printing, Time, Unknown, Video

  GetDeleteGroups [static]
Get list of all deletable group names.

    @delGroups = Image::ExifTool::GetDeleteGroups();

Inputs:
    None.

Return Values:
    A list of deletable group names in alphabetical order. The current list of deletable group names is:

    AFCP, CIFF, CanonVRD, EXIF, ExifIFD, Ducky, File, FlashPix, FotoStation, GlobParamIFD, GPS, IFD0, IFD1, InteropIFD, ICC_Profile, IPTC, JFIF, MakerNotes, Meta, MetaIFD, MIE, PhotoMechanic, Photoshop, PNG, PrintIM, RMETA, SubIFD, Trailer, XMP

    All names in this list are either family 0 or family 1 group names, with the exception of 'Trailer' which allows all trailers in JPEG and TIFF-format images to be deleted at once, including unknown trailers. To schedule a group for deletion, call "SetNewValue" with an undefined value and a tag name like 'Trailer:*'.

  GetFileType [static]
Get type of file given file name.

    my $type = Image::ExifTool::GetFileType($filename);
    my $desc = Image::ExifTool::GetFileType($filename, 1);

Inputs:
    0) [optional] File name (or just an extension)

    1) [optional] Flag to return a description instead of a type

Return Value:
    A string, based on the file extension, which represents the type of file. Returns undefined value if file type is not supported by ExifTool. In array context, may return more than one file type if the file may be different formats. Returns a list of extensions for all recognized file types if no input extension is specified.

  CanWrite [static]
Can the specified file or file type be written?

    my $writable = Image::ExifTool::CanWrite($filename);

Inputs:
    0) File name, file extension, or file type

Return Value:
    True if the specified file type can be written (edited).

  CanCreate [static]
Can the specified file or file type be created?

    my $creatable = Image::ExifTool::CanCreate($filename);

Inputs:
    0) File name, file extension, or file type

Return Value:
    True if the specified file type can be created from scratch. Currently, this can only be done with XMP, MIE, ICC and VRD files.

AUTHOR
Copyright 2003-2008, Phil Harvey

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

CREDITS
Many people have helped in the development of ExifTool through their bug reports, comments and suggestions, and/or additions to the code. See html/index.html in the Image::ExifTool distribution package for a list of people who have contributed to this project.

SEE ALSO
exiftool(1), Image::ExifTool::TagNames(3pm), Image::ExifTool::Shortcuts(3pm), Image::ExifTool::Shift.pl, Image::Info(3pm), Image::MetaData::JPEG(3pm)