Precision of values in IG_ISIS_TAG_GRAYRESPONSECURVE. 0x0122 ∙ 290
IG_ISIS_TAG_GRAYRESPONSEUNIT the precision of the values contained in IG_ISIS_TAG_GRAYRESPONSECURVE.
IG_ISIS_TAG_TYPE_SHORT
None
The precision is specified as an integer that represents a power of tenths factor. For example, if IG_ISIS_TAG_GRAYRESPONSEUNIT is set to 4, this represents then-thousandths of a unit, and a IG_ISIS_TAG_GRAYRESPONSECURVE value for a particular gray level is 3455, then the actual value is 0.3455.
Optical densitometers typically measure densities in the range of 0.0 to 2.0. For historical reasons, the default IG_ISIS_TAG_GRAYRESPONSEUNIT is 2; however, the TIFF specification recommends using 3 for greater accuracy.