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improve posterize algorithm

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Cristy
2024-02-02 22:29:24 -05:00
parent 122a1f6589
commit 92c93c30ad
1 changed files with 19 additions and 11 deletions
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MagickCore/quantize.c
+19 -11
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@@ -2851,12 +2851,18 @@ static inline double MagickRound(double x)
return(ceil(x));
}
static inline Quantum PosterizePixel(const Quantum pixel,const size_t levels)
{
ssize_t
alpha = (ssize_t) ((QuantumRange+1)/levels);
return(ClampToQuantum((MagickRealType) (alpha*(pixel/alpha))));
}
MagickExport MagickBooleanType PosterizeImage(Image *image,const size_t levels,
const DitherMethod dither_method,ExceptionInfo *exception)
{
#define PosterizeImageTag "Posterize/Image"
#define PosterizePixel(pixel) ClampToQuantum((MagickRealType) (QuantumScale* \
(pixel)*(levels-1))*(QuantumRange*PerceptibleReciprocal((double) levels-1)))
CacheView
*image_view;
@@ -2880,6 +2886,8 @@ MagickExport MagickBooleanType PosterizeImage(Image *image,const size_t levels,
assert(exception->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
if (levels == 0)
return(MagickTrue);
if (image->storage_class == PseudoClass)
#if defined(MAGICKCORE_OPENMP_SUPPORT)
#pragma omp parallel for schedule(static) shared(progress,status) \
@@ -2892,16 +2900,16 @@ MagickExport MagickBooleanType PosterizeImage(Image *image,const size_t levels,
*/
if ((GetPixelRedTraits(image) & UpdatePixelTrait) != 0)
image->colormap[i].red=(double)
PosterizePixel(image->colormap[i].red);
PosterizePixel(image->colormap[i].red,levels);
if ((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0)
image->colormap[i].green=(double)
PosterizePixel(image->colormap[i].green);
PosterizePixel(image->colormap[i].green,levels);
if ((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0)
image->colormap[i].blue=(double)
PosterizePixel(image->colormap[i].blue);
PosterizePixel(image->colormap[i].blue,levels);
if ((GetPixelAlphaTraits(image) & UpdatePixelTrait) != 0)
image->colormap[i].alpha=(double)
PosterizePixel(image->colormap[i].alpha);
PosterizePixel(image->colormap[i].alpha,levels);
}
/*
Posterize image.
@@ -2932,17 +2940,17 @@ MagickExport MagickBooleanType PosterizeImage(Image *image,const size_t levels,
for (x=0; x < (ssize_t) image->columns; x++)
{
if ((GetPixelRedTraits(image) & UpdatePixelTrait) != 0)
SetPixelRed(image,PosterizePixel(GetPixelRed(image,q)),q);
SetPixelRed(image,PosterizePixel(GetPixelRed(image,q),levels),q);
if ((GetPixelGreenTraits(image) & UpdatePixelTrait) != 0)
SetPixelGreen(image,PosterizePixel(GetPixelGreen(image,q)),q);
SetPixelGreen(image,PosterizePixel(GetPixelGreen(image,q),levels),q);
if ((GetPixelBlueTraits(image) & UpdatePixelTrait) != 0)
SetPixelBlue(image,PosterizePixel(GetPixelBlue(image,q)),q);
SetPixelBlue(image,PosterizePixel(GetPixelBlue(image,q),levels),q);
if (((GetPixelBlackTraits(image) & UpdatePixelTrait) != 0) &&
(image->colorspace == CMYKColorspace))
SetPixelBlack(image,PosterizePixel(GetPixelBlack(image,q)),q);
SetPixelBlack(image,PosterizePixel(GetPixelBlack(image,q),levels),q);
if (((GetPixelAlphaTraits(image) & UpdatePixelTrait) != 0) &&
(image->alpha_trait != UndefinedPixelTrait))
SetPixelAlpha(image,PosterizePixel(GetPixelAlpha(image,q)),q);
SetPixelAlpha(image,PosterizePixel(GetPixelAlpha(image,q),levels),q);
q+=GetPixelChannels(image);
}
if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)