@@ -192,6 +207,7 @@
Interactively Animate an Image Sequence
Convert to and from Cipher Pixels
Working with Image Lists
+
Image View Methods
Get or Set Image Pixels
Working with Cache Views
The Pixel FIFO
@@ -210,7 +226,7 @@
After you write your MagickCore program, compile it like this:
-
$magick> cc `MagickCore-config --cflags --cppflags` core.c \
`MagickCore-config --ldflags --libs`
+
$magick> cc `MagickCore-config --cflags --cppflags` -O2 core.c \
`MagickCore-config --ldflags --libs`
Here is a example program that utilizes the MagickCore API to get you started, core.c. It reads a GIF image, creates a thumbnail, and writes it to disk in the PNG image format.
@@ -280,14 +296,136 @@
}
+
Now lets perform the same contrast enhancement while taking advantage of our dual or quad-core processing system by running the algorithm in parallel utilizing wand views. The sigmoidal-contrast.c module reads an image, applies sigmoidal non-linearity contrast control, and writes the result to disk just like the previous contrast enhancement program, but now it does its work in parallel (assumes ImageMagick is built with OpenMP support).
+
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <magick/MagickCore.h>
+
+static MagickBooleanType SigmoidalContrast(ImageView *contrast_view,
+ const ssize_t y,const int id,void *context)
+{
+#define QuantumScale ((MagickRealType) 1.0/(MagickRealType) QuantumRange)
+#define SigmoidalContrast(x) \
+ (QuantumRange*(1.0/(1+exp(10.0*(0.5-QuantumScale*x)))-0.0066928509)*1.0092503)
+
+ RectangleInfo
+ extent;
+
+ register IndexPacket
+ *indexes;
+
+ register PixelPacket
+ *pixels;
+
+ register ssize_t
+ x;
+
+ extent=GetImageViewExtent(contrast_view);
+ pixels=GetImageViewAuthenticPixels(contrast_view);
+ for (x=0; x < (ssize_t) (extent.width-extent.x); x++)
+ {
+ pixels[x].red=RoundToQuantum(SigmoidalContrast(pixels[x].red));
+ pixels[x].green=RoundToQuantum(SigmoidalContrast(pixels[x].green));
+ pixels[x].blue=RoundToQuantum(SigmoidalContrast(pixels[x].blue));
+ pixels[x].opacity=RoundToQuantum(SigmoidalContrast(pixels[x].opacity));
+ }
+ indexes=GetImageViewAuthenticIndexes(contrast_view);
+ if (indexes != (IndexPacket *) NULL)
+ for (x=0; x < (ssize_t) (extent.width-extent.x); x++)
+ indexes[x]=(IndexPacket) RoundToQuantum(SigmoidalContrast(indexes[x]));
+ return(MagickTrue);
+}
+
+int main(int argc,char **argv)
+{
+#define ThrowImageException(image) \
+{ \
+ \
+ CatchException(exception); \
+ if (contrast_image != (Image *) NULL) \
+ contrast_image=DestroyImage(contrast_image); \
+ exit(-1); \
+}
+#define ThrowViewException(view) \
+{ \
+ char \
+ *description; \
+ \
+ ExceptionType \
+ severity; \
+ \
+ description=GetImageViewException(view,&severity); \
+ (void) fprintf(stderr,"%s %s %lu %s\n",GetMagickModule(),description); \
+ description=DestroyString(description); \
+ exit(-1); \
+}
+
+ ExceptionInfo
+ *exception;
+
+ Image
+ *contrast_image;
+
+ ImageInfo
+ *image_info;
+
+ ImageView
+ *contrast_view;
+
+ MagickBooleanType
+ status;
+
+ if (argc != 3)
+ {
+ (void) fprintf(stdout,"Usage: %s image sigmoidal-image\n",argv[0]);
+ exit(0);
+ }
+ /*
+ Read an image.
+ */
+ MagickCoreGenesis(*argv,MagickTrue);
+ image_info=AcquireImageInfo();
+ (void) CopyMagickString(image_info->filename,argv[1],MaxTextExtent);
+ exception=AcquireExceptionInfo();
+ contrast_image=ReadImage(image_info,exception);
+ if (contrast_image == (Image *) NULL)
+ ThrowImageException(contrast_image);
+ /*
+ Sigmoidal non-linearity contrast control.
+ */
+ contrast_view=NewImageView(contrast_image);
+ if (contrast_view == (ImageView *) NULL)
+ ThrowImageException(contrast_image);
+ status=UpdateImageViewIterator(contrast_view,SigmoidalContrast,(void *) NULL);
+ if (status == MagickFalse)
+ ThrowImageException(contrast_image);
+ contrast_view=DestroyImageView(contrast_view);
+ /*
+ Write the image then destroy it.
+ */
+ status=WriteImages(image_info,contrast_image,argv[2],exception);
+ if (status == MagickFalse)
+ ThrowImageException(contrast_image);
+ contrast_image=DestroyImage(contrast_image);
+ exception=DestroyExceptionInfo(exception);
+ image_info=DestroyImageInfo(image_info);
+ MagickCoreTerminus();
+ return(0);
+}
+
+