RGBToHLS

RGB to HLS color conversion. More...

Functions
NppStatus	nppiRGBToHLS_8u_C3R (const Npp8u *pSrc, int nSrcStep, Npp8u *pDst, int nDstStep, NppiSize oSizeROI)
	3 channel 8-bit unsigned packed RGB to 3 channel 8-bit unsigned packed HLS color conversion. More...
NppStatus	nppiRGBToHLS_8u_AC4R (const Npp8u *pSrc, int nSrcStep, Npp8u *pDst, int nDstStep, NppiSize oSizeROI)
	4 channel 8-bit unsigned packed RGB with alpha to 4 channel 8-bit unsigned packed HLS with alpha color conversion. More...

Detailed Description

RGB to HLS color conversion.

This is how NPP converts gamma corrected RGB or BGR to HLS. This code uses the fmaxf() and fminf() 32 bit floating point math functions.

*  Npp32f nNormalizedR = (Npp32f)R * 0.003921569F;  // / 255.0F

*  Npp32f nNormalizedG = (Npp32f)G * 0.003921569F;
*  Npp32f nNormalizedB = (Npp32f)B * 0.003921569F;
*  Npp32f nS;
*  Npp32f nH;
*  // Lightness

*  Npp32f nMax = fmaxf(nNormalizedR, nNormalizedG);
*         nMax = fmaxf(nMax, nNormalizedB);
*  Npp32f nMin = fminf(nNormalizedR, nNormalizedG);
*         nMin = fminf(nMin, nNormalizedB);
*  Npp32f nL = (nMax + nMin) * 0.5F;
*  Npp32f nDivisor = nMax - nMin;
*  // Saturation

*  if (nDivisor == 0.0F) // achromatics case

*  {
*      nS = 0.0F;
*      nH = 0.0F;
*  }
*  else // chromatics case

*  {
*      if (nL > 0.5F)
*          nS = nDivisor / (1.0F - (nMax + nMin - 1.0F));
*      else

*          nS = nDivisor / (nMax + nMin);
*  }
*  // Hue

*  Npp32f nCr = (nMax - nNormalizedR) / nDivisor;
*  Npp32f nCg = (nMax - nNormalizedG) / nDivisor;
*  Npp32f nCb = (nMax - nNormalizedB) / nDivisor;
*  if (nNormalizedR == nMax)
*      nH = nCb - nCg;
*  else if (nNormalizedG == nMax)
*      nH = 2.0F + nCr - nCb;
*  else if (nNormalizedB == nMax)
*      nH = 4.0F + nCg - nCr;
*  nH = nH * 0.166667F; // / 6.0F       

*  if (nH < 0.0F)
*      nH = nH + 1.0F;
*  H = (Npp8u)(nH * 255.0F);
*  L = (Npp8u)(nL * 255.0F);
*  S = (Npp8u)(nS * 255.0F);
*  

Function Documentation

NppStatus nppiRGBToHLS_8u_AC4R	(	const Npp8u *	pSrc,
		int	nSrcStep,
		Npp8u *	pDst,
		int	nDstStep,
		NppiSize	oSizeROI
	)

4 channel 8-bit unsigned packed RGB with alpha to 4 channel 8-bit unsigned packed HLS with alpha color conversion.

Parameters

pSrc	Source-Image Pointer.
nSrcStep	Source-Image Line Step.
pDst	Destination-Image Pointer.
nDstStep	Destination-Image Line Step.
oSizeROI	Region-of-Interest (ROI).

Returns

Image Data Related Error Codes, ROI Related Error Codes

NppStatus nppiRGBToHLS_8u_C3R	(	const Npp8u *	pSrc,
		int	nSrcStep,
		Npp8u *	pDst,
		int	nDstStep,
		NppiSize	oSizeROI
	)

3 channel 8-bit unsigned packed RGB to 3 channel 8-bit unsigned packed HLS color conversion.

Parameters

pSrc	Source-Image Pointer.
nSrcStep	Source-Image Line Step.
pDst	Destination-Image Pointer.
nDstStep	Destination-Image Line Step.
oSizeROI	Region-of-Interest (ROI).

Returns

Image Data Related Error Codes, ROI Related Error Codes