Data Type:

TW_UINT16

Purpose:

Allows the application and Source to identify which compression schemes they have in common for Buffered Memory and File transfers.

Since only certain file formats support compression, this capability must be negotiated after setting the desired file format with ICAP_IMAGEFILEFORMAT.

• TWCP_NONE - All Sources must support this
• TWCP_PACKBITS - Macintosh PackBits format (can be used with TIFF or PICT)
• TWCP_GROUP31D
• TWCP_GROUP31DEOL
• TWCP_GROUP32D
• TWCP_GROUP4 - Are all from the CCITT specification (now ITU), intended for document images (can be used with TIFF)
• TWCP_JPEG - Intended for the compression of color photographs (can be used with TIFF, JFIF or SPIFF)
• TWCP_LZW - A compression licensed by UNISYS (can be used with TIFF)
• TWCP_JBIG - Intended for bi-tonal and grayscale document images (can be used with TIFF or SPIFF)
• TWCP_PNG - This compression can only be used if ICAP_IMAGEFILEFORMAT is set to TWFF_PNG
• TWCP_RLE4
• TWCP_RLE8
• TWCP_BITFIELDS - These compressions can only be used if ICAP_IMAGEFILEFORMAT is set to TWFF_BMP

Applications must not assume that a Source can provide compressed Buffered Memory or File transfers, because many cannot. The application should use MSG_SET on a TW_ONEVALUE container to specify the compression type for future transfers.

Valid Values:

• TWCP_NONE = 0
• TWCP_PACKBITS = 1
• TWCP_GROUP31D = 2
• TWCP_GROUP31DEOL = 3
• TWCP_GROUP32D = 4
• TWCP_GROUP4 = 5
• TWCP_JPEG = 6
• TWCP_LZW = 7
• TWCP_JBIG = 8
• TWCP_PNG = 9
• TWCP_RLE4 = 10
• TWCP_RLE8 = 11
• TWCP_BITFIELDS = 12

Default Value:

TWCP_NONE