Gamma curve adjustment for scanning. 0x050F ∙ 1295

IG_ISIS_TAG_GAMMA allows an application to adjust the scanner's gamma curve.

Type:

IG_ISIS_TAG_TYPE_SHORT

Drivers:

Drivers for all scanners that have either automatic or downloadable gamma correction tables.

Values:

Legal values for IG_ISIS_TAG_GAMMA include the following, but may also include other values depending on the scanner's specific capabilities. Query the choices for IG_ISIS_TAG_GAMMA to determine the specific values available from the currently-selected scanner.

Value	Defined Constant	Meaning
0	IG_ISIS_GAMMA_AUTO	Scanner's gamma correction is set to automatic.
0x80	IG_ISIS_GAMMA_DOWNLOAD1	Scanner's gamma correction is set to the first downloaded correction table.
0x81	IG_ISIS_GAMMA_DOWNLOAD2	Scanner's gamma correction is set to the second downloaded correction table.
0x82	IG_ISIS_GAMMA_DOWNLOAD3	Scanner's gamma correction is set to the third downloaded correction table.
0x83	IG_ISIS_GAMMA_DOWNLOAD4	Scanner's gamma correction is set to the fourth downloaded correction table.
0x84	IG_ISIS_GAMMA_DOWNLOAD5	Scanner's gamma correction is set to the fifth downloaded correction table.
0x85	IG_ISIS_GAMMA_DOWNLOAD6	Scanner's gamma correction is set to the sixth downloaded correction table.

The downloadable gamma tables are typically lists of 256 values.

Remarks:

Not all scanners support gamma correction. Of those that do, some provide automatic gamma correction, and may provide downloadable gamma correction tables. Other scanners have built-in gamma correction values that are specific to the scanner. For example, the Ricoh IS-520 has many values, including IG_ISIS_TAG_GAMMA_BOTTOMCLIP, IG_ISIS_TAG_GAMMA_1TO1INVERT, IG_ISIS_TAG_GAMMA_SHARP_61, and so forth. Refer to your scanner's documentation and to the individual scanner tag documentation included with this toolkit for additional information.