Use Metadata Structures

Currently, ImageGear provides simplified access for the following types of metadata:

Metadata Type	ImageGear Class	ImGearMetadataHead Property
TIFF	ImGearTIFFMetadata Class	ImGearMetadataHead.TIFF
EXIF	ImGearEXIFMetadata Class	ImGearMetadataHead.EXIF
IPTC	ImGearIPTCMetadata Class	ImGearMetadataHead.IPTC

The following table shows the file formats that contain the metadata structure:

Metadata Type	File Formats
TIFF	TIFF, JFIF JPEG, Camera Raw formats
EXIF	TIFF, JFIF JPEG, Camera Raw formats
IPTC	TIFF, JFIF JPEG, Camera Raw formats

EXIF metadata also has subtrees that are represented by the following classes:

Metadata Type	ImageGear Class	ImGearEXIFMetadata Property
EXIF GPS	ImGearEXIFGPSMetadata Class	ImGearEXIFMetadata.GPS
EXIF Interoperability	ImGearEXIFInteropMetadata Class	ImGearEXIFMetadata.Interoperability

Classes of the simplified API do not store their own copy of the metadata values. Instead, they access values that are stored in the general metadata tree.

If the page does not contain a specific metadata structure, the corresponding accessor returns null. For example, if an ImGearPage Class was loaded from a BMP image, it will not contain EXIF metadata, and page.Metadata.EXIF will return null.

Simplified API only supports metadata items that were known to Accusoft at the time of toolkit development, i.e., standard or well-known items. Use general metadata API to access custom and non-standard metadata items.

The EXIF specification uses a subset of tags defined in the TIFF specification. Due to this, ImGearEXIFMetadata Class contains a subset of TIFF tags (those that are referenced in the EXIF specification). These tags can be accessed through either ImGearEXIFMetadata Class or ImGearTIFFMetadata Class accessors.