L_SetPaintGamma

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_SetPaintGamma(pBitmap, uValue)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_UINT uValue;	/* gamma value */

Sets the current gamma correction value for the specified bitmap. This value can be retrieved using the L_GetPaintGamma function.

Parameter	Description
pBitmap	Pointer to the bitmap handle that references the bitmap to be affected.
uValue	Unsigned integer that represents the gamma value. It can be any number greater than 0. The default value is 100.
	Because this is an unsigned integer, it is 100 times the actual gamma value. For example, use 235 to set a gamma value of 2.35.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

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.

When applying contrast, gamma, and intensity changes to a bitmap, LEAD applies the changes in the following order:

Contrast

Intensity

Gamma

Required DLLs and Libraries

LTDIS

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Windows 95 / 98 / Me, Windows 2000 / XP, Windows CE.

Functions:	L_GetPaintContrast, L_SetPaintContrast, L_GetPaintGamma, L_GetPaintIntensity, L_SetPaintIntensity, L_DlgGammaAdjustment
Topics:	Raster Image Functions: Displaying Images
	Changing Brightness and Contrast
	Raster Image Functions: Changing Brightness and Contrast