GammaCorrect method (ILEADRasterProcess)

Visual Basic example

Visual C++ 5.0 example

Delphi 4 example

C++ Builder example

 

Syntax

short GammaCorrect (ILEADRaster *pRaster, short iGamma);

Overview

Refer to Changing Brightness and Contrast.

Remarks

Adjusts the intensity of colors in the bitmap by changing the gamma constant that is used to map the intensity values.

Intensity values ideally follow a logarithmic progression, because the eye perceives changes in intensity as being equal when the ratio of change is equal. For example, we would see a change from 0.1 to 0.2 as being equal to a change from 0.2 to 0.4.

Gamma is a standard constant that is used to calculate the progression. For most CRTs the gamma constant is in the range of 2.2 to 2.5.

This method supports 12 and 16-bit grayscale images and 48 and 64-bit color images. Support for 12 and 16-bit grayscale images and 48 and 64-bit color images is available only in the Document/Medical toolkits.

This method does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this method.

This method supports signed images.

See Also

Elements:

Intensity method, Contrast method, HistoContrast method, HistoEqualize method, StretchIntensity method

Topics:

Raster Images: Modifying Intensity Values

 

Raster Images: Where the Region Preempts the Bitmap