TIFF File Comments

When reading or updating TIFF comments, you must specify the comment type using the following constants.

For TIFF files: Each comment field can contain a character string. The maximum field size is 32K, except for the date-time field, which are always 20.

Please note that LEADTOOLS also supports IPTC Comments, which can be saved inside TIFF files. For more information, refer to IPTC Comments.

Value	Meaning
RasterCommentMetadataType.Artist	Person who created the image.
RasterCommentMetadataType.Copyright	Copyright notice.
RasterCommentMetadataType.DateTime	Date and time (YYYY:MM:DD HH:MM:SS). The field length is 20, counting the NULL terminator.
RasterCommentMetadataType.Description	Description of the image.
RasterCommentMetadataType.HostComputer	Computer and operating system in use.
RasterCommentMetadataType.Make	Manufacturer of the equipment used to create the image.
RasterCommentMetadataType.Model	Model name and number of the equipment.
RasterCommentMetadataType.NameOfDocument	Name of the document from which the image was scanned.
RasterCommentMetadataType.NameOfPage	Page name from which the image was scanned.
RasterCommentMetadataType.Software NOTE: If you are using the Nag version of Leadtools.dll, this comment is fixed and cannot be changed.	Name and version of the software package used to create the image.

To obtain specified tagged data from a TIFF file or stream, use one of the RasterCodecs.ReadTag methods. To write or change a tag to an existing file, use one of the RasterCodecs.WriteTag or RasterCodecs.WriteTags methods.

For more information about file comments, refer to RasterCodecs.ReadComment and RasterCodecs.WriteComment.

For technical reasons, the following restrictions apply when you pass an IFD offset by setting the RasterCodecs.Options.Tiff.Load.ImageFileDirectoryOffset property if you set PageNumber to 1:

You cannot add tags, comments or GeoKeys to this IFD. You can only update existing tags, comments or GeoKeys in this IFD.
You cannot replace the TIFF page indicated by this IFD.
You cannot add a page before the this IFD.
You cannot delete the page indicated by this IFD. You can, however, add tags, comments or GeoKeys to an IFD that follows the specified IFD (for example, if PageNumber is >= 2). You can also replace or delete a page that follows the specified IFD and you can insert a page after this IFD.

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