ImageGear .NET uses its general metadata engine for all file formats, including DICOM. When ImageGear loads a DICOM image, it builds a metadata tree structure and attached it to the new ImGearPage Class object. Use ImageGear .NET Metadata support classes to access data items in this tree.

A DICOM file includes one header with metadata, and zero, one, or multiple images. Metadata applies to all images in the file. ImageGear loads a copy of DICOM metadata into every loaded page. DICOM Document metadata is empty.

DICOM tags map to ImageGear metadata tags as follows:

Tag group number, element number	ImGearMetadataNode.Tag Property
Value Representation	ImGearMetadataLeaf.NativeType Field
Value Length	Not stored explicitly. Application can use string and array lengths instead.
Value Multiplicity (Item count)	Not stored explicitly. For values of OB/OW/OF it is always 1. For other Value Representations, if data is singular it is 1, otherwise it is equal to the length of the data array.
Data	ImGearMetadataLeaf.Data Property

"Sequence" (SQ) tags are represented by nested metadata trees. SQ contains one or more Sequence Items, and cannot contain normal DICOM tags. Sequence Item contains a set of DICOM tags.

The following tags are read from the file, but not added to the metadata tree:

• Group lengths
• Sequence delimitation items
• Item delimitation items

The following table lists the mapping between DICOM Value Representations and .NET system types: 

VR	Meaning	System Type to which It Converts on Reading	Allowed System Types on Writing
AE	Application Entity	String	String
AS	Age String	String	String
AT	Attribute Tag	String	String
CS	Code String	String	String
DA	Date	String	String
DS	Decimal String	double	all numeric types, String
DT	Date Time	String	String
FL	Floating Point Single	float	all numeric types, String
FD	Floating Point Double	double	all numeric types, String
IS	Integer String	long (64-bit)	all integer types, String
LO	Long String	String	String
LT	Long Text	String	String
OB	Other Byte String	byte[]	byte[]
OW	Other Word String	ushort[]	ushort[]
PN	Person Name	String	String
SH	Short String	String	String
SL	Signed Long	int	all integer types, String
SQ	Sequence	-	-
SS	Signed Short	short	all integer types, String
ST	Short Text	String	String
TM	Time	String	String
UI	Unique Identifier	String	String
UL	Unsigned Long	uint	all integer types, String
UN	Unknown	byte[]	byte[]
US	Unsigned Short	ushort	all integer types, String
UT	Unlimited Text	String	String
OF	Other Float String	float[]	float[], double[]

For types other than OB, OW and OF, if the system type is an array, a multivalued data element is saved.

Example of conversion on metadata reading:

VR	Tag Value	Metadata Leaf Data Type	Metadata Leaf Value
US	0x0001	ushort	1
OW	0x0001 0x0002 0x0003	ushort[]	{1, 2, 3}
DS	"0.12345\0.6789"	double[]	{0.12345, 0.6789}
CS	"MR"	string	"MR"
CS	"ORIGINAL\PRIMARY"	string[]	{"ORIGINAL", "PRIMARY"}