Herd Software Development
DaVinci Graphics Library
DaVinci Documentation

Leonardo: The GammaCorrectionApplyToDIB function

The function GammaCorrectionApplyToDIB changes the color representation of a DIB according to the gamma correction.

void API GammaCorrectionApplyToDIB(
HDIB	HDIB,
int	Gamma10000,
int	iReserved1,
int	iReserved2,
LPBYTE	lpabGamma);

HDIB HDIB Handle of the DIB to be adapted

iGamma1000 int Gamma correction value, multiplied by 10000.(see Gamma correction))

iReserved1 int Reserved for future use. Applications should specify this value as 0.

iReserved2 int Reserved for future use. Applications should specify this value as 0.

lpabGamma LPBYTE Pointer to an array of 256 byte values previously computed by GammaCorrectionGetArray, or NULL.

Remarks

The specified DIB is not returned as a gamma-corrected copy; the source image itself is gamma-corrected resulting in permanent change to the DIB. The process cannot be undone. Create a copy of the DIB prior to execution if needed using CopyHandle.

DIBs which require color palettes (biBitCount <= 8) will only have their palettes modified, so processing speed will be quite rapid. Higher-resolution DIBs require every byte of the DIB to be modified which takes considerably longer.

Example: Apply gamma correction to a DIB.

HDIB GammaCorrect(float Gamma, HDIB hOriginalDIB)
{
  HDIB hDIB = CopyHandle(hOriginalDIB);
  BYTE Array[256];
  if (hDIB)
  {
     GammaCorrectionGetArray(Gamma * 10000, 0, 0, Array);
     GammaCorrectionApplyToDIB(hDIB, Gamma*10000, 0, 0, Array);
  }
  return hDIB;
} // GammaCorrect