Gamma curve adjustment for scanning. 0x050F ∙ 1295
IG_ISIS_TAG_GAMMA allows an application to adjust the scanner's gamma curve.
IG_ISIS_TAG_TYPE_SHORT
Drivers for all scanners that have either automatic or downloadable gamma correction tables.
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.
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.