This section provides detailed information about the image formats and compressions that ImageGear supports.

• File Formats provides background information about different types of file formats, and contains additional topics that provide information on the following:
  • Format Bit Depths is a table that lists the bit depths and the read/write capabilities of the supported formats. Using this table, you can easily find out whether an image can be converted to a particular format.
  • File Formats Reference provides information about every ImageGear supported format, its ID, supported versions, encoding type, multi-page and alpha channel support, supported compressions, color spaces and bit depths for read and write, as well as information about ImageGear supported features and filter control parameters.
  • Metadata Structures provides detailed information about ImageGear supported metadata.
• Compressions provides information about every ImageGear supported imaging compression.

Supported Formats

The following formats are supported by ImageGear PDF:

Format	Full Name
BMP	Microsoft Windows Bitmap
CLP	Windows Clipboard
CUR	Windows Cursor
GIF	CompuServe Graphic Interchange Format
ICO	Windows Icon
JPEG	JPEG File Interchange Format
PDF	Adobe Portable Document Format
PNG	Portable Network Graphics
PS	Adobe PostScript
TIFF	Tagged Image File Format

Supported Compressions

All supported formats use compression for storing data on a file. ImageGear PDF uses the following compressions:

Format	Full Name	Formats Supported
CCITT Group 3 Compression	CCITT Group 3	PDF, PS, TIFF
CCITT Group 3 2D Compression	CCITT Group 3 2D	PDF, PS, TIFF
CCITT Group 4 Compression	CCITT Group 4	PDF, PS, TIFF
Deflate Compression	Deflate Compression	PDF, PS, TIFF, PNG
Huffman Compression	Huffman Encoding	TIFF
JPEG Compressions "Lossy" JPEG Compression Lossless JPEG Compression Progressive JPEG Compression	JPEG Compression	Lossy: JPEG, PDF, PS, TIFF Lossless: JPEG, TIFF Progressive: JPEG
LZW (Lempel-Ziv-Welch) Compression	Lempel-Zif-Welch (LZW) Compression	GIF, PDF, PS, TIFF
Packbits Compression	Packed Bits Compression	TIFF
RLE Compression	Run Length Encoding Compression	BMP, CLP, PDF, PS

Encoding vs. Compressing

These two words are often used interchangeably in discussions of graphics file formats. Encoding is actually a broad term under which compression falls. For the sake of clarity, use these terms separately with the following intended meanings:

• Encoding - The manner that data is stored when uncompressed (binary, ASCII, etc.), how it is packed (e.g., 4-bit pixels may be packed at a rate of two pixels per byte), and the unique set of symbols used to represent the range of data items.
• Compressing - A "physical" rewriting of the graphics data so that it is represented by a smaller set of data.