#include "MagickCore/image-private.h"
#include "MagickCore/list.h"
#include "MagickCore/log.h"
+#include "MagickCore/matrix.h"
#include "MagickCore/memory_.h"
#include "MagickCore/memory-private.h"
#include "MagickCore/monitor.h"
% The format of the EdgeImage method is:
%
% Image *CannyEdgeImage(const Image *image,const double radius,
-% const double sigma,const double low_factor,const double high_factor,
+% const double sigma,const double low_percent,const double high_percent,
% const size_t threshold,ExceptionInfo *exception)
%
% A description of each parameter follows:
%
% o sigma: the sigma of the gaussian smoothing filter.
%
-% o low_factor: use this low factor in hysteresis.
+% o low_percent: percentage of pixels in the low threshold.
%
-% o hight_factor: use this high factor in hysteresis.
+% o high_percent: percentage of pixels in the high threshold.
%
% o exception: return any errors or warnings in this structure.
%
*/
+
+typedef struct _CannyInfo
+{
+ double
+ Dx,
+ Dy,
+ magnitude,
+ intensity;
+} CannyInfo;
+
+static MagickBooleanType IsAuthenticPixel(const Image *image,const ssize_t x,
+ const ssize_t y)
+{
+ if ((x < 0) || (x >= (ssize_t) image->columns))
+ return(MagickFalse);
+ if ((y < 0) || (y >= (ssize_t) image->rows))
+ return(MagickFalse);
+ return(MagickTrue);
+}
+
+static MagickBooleanType TraceEdge(Image *edge_image,CacheView *edge_view,
+ MatrixInfo *pixel_cache,const ssize_t x,const ssize_t y,
+ const double threshold,ExceptionInfo *exception)
+{
+ CannyInfo
+ pixel;
+
+ Quantum
+ *q;
+
+ MagickBooleanType
+ status;
+
+ q=GetCacheViewAuthenticPixels(edge_view,x,y,1,1,exception);
+ if ((q != (Quantum *) NULL) && (GetPixelIntensity(edge_image,q) == 0))
+ {
+ ssize_t
+ v;
+
+ *q=QuantumRange;
+ status=SyncCacheViewAuthenticPixels(edge_view,exception);
+ if (status != MagickFalse)
+ {
+ for (v=(-1); v <= 1; v++)
+ {
+ ssize_t
+ u;
+
+ for (u=(-1); u <= 1; u++)
+ {
+ if (((y != 0) || (u != 0)) &&
+ (IsAuthenticPixel(edge_image,x+u,y+v) != MagickFalse))
+ {
+ (void) GetMatrixElement(pixel_cache,x+u,y+v,&pixel);
+ if (pixel.intensity >= threshold)
+ {
+ status=TraceEdge(edge_image,edge_view,pixel_cache,x+u,y+v,
+ threshold,exception);
+ if (status != MagickFalse)
+ return(MagickTrue);
+ }
+ }
+ }
+ }
+ return(MagickTrue);
+ }
+ }
+ return(MagickFalse);
+}
+
MagickExport Image *CannyEdgeImage(const Image *image,const double radius,
- const double sigma,const double low_factor,const double high_factor,
+ const double sigma,const double low_percent,const double high_percent,
ExceptionInfo *exception)
{
+ CacheView
+ *edge_view;
+
+ char
+ geometry[MaxTextExtent];
+
+ double
+ high_threshold,
+ low_threshold;
+
Image
*edge_image;
+ KernelInfo
+ *kernel_info;
+
+ MagickBooleanType
+ status;
+
+ MatrixInfo
+ *pixel_cache;
+
+ register ssize_t
+ i;
+
+ size_t
+ *histogram,
+ number_pixels;
+
+ ssize_t
+ count,
+ y;
+
assert(image != (const Image *) NULL);
assert(image->signature == MagickSignature);
if (image->debug != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
assert(exception != (ExceptionInfo *) NULL);
assert(exception->signature == MagickSignature);
- edge_image=(Image *) NULL;
+ /*
+ Filter out noise before trying to locate and detect any edges.
+ */
+ (void) FormatLocaleString(geometry,MaxTextExtent,
+ "blur:%.20gx%.20g;blur:%.20gx%.20g+90",radius,sigma,radius,sigma);
+ kernel_info=AcquireKernelInfo(geometry);
+ if (kernel_info == (KernelInfo *) NULL)
+ ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
+ edge_image=MorphologyApply(image,ConvolveMorphology,1,kernel_info,
+ UndefinedCompositeOp,0.0,exception);
+ kernel_info=DestroyKernelInfo(kernel_info);
+ if (edge_image == (Image *) NULL)
+ return((Image *) NULL);
+ if (SetImageColorspace(edge_image,GRAYColorspace,exception) == MagickFalse)
+ {
+ edge_image=DestroyImage(edge_image);
+ return((Image *) NULL);
+ }
+ /*
+ Find the edge strength by taking the gradient of the image.
+ */
+ pixel_cache=AcquireMatrixInfo(edge_image->columns,edge_image->rows,
+ sizeof(CannyInfo),exception);
+ if (pixel_cache == (MatrixInfo *) NULL)
+ {
+ edge_image=DestroyImage(edge_image);
+ return((Image *) NULL);
+ }
+ status=MagickTrue;
+ edge_view=AcquireVirtualCacheView(edge_image,exception);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+ #pragma omp parallel for schedule(static,4) shared(status) \
+ magick_threads(edge_image,edge_image,edge_image->rows,1)
+#endif
+ for (y=0; y < (ssize_t) edge_image->rows; y++)
+ {
+ register const Quantum
+ *restrict p;
+
+ register ssize_t
+ x;
+
+ if (status == MagickFalse)
+ continue;
+ p=GetCacheViewVirtualPixels(edge_view,-1,y-1,edge_image->columns+2,3,
+ exception);
+ if (p == (const Quantum *) NULL)
+ {
+ status=MagickFalse;
+ continue;
+ }
+ for (x=0; x < (ssize_t) edge_image->columns; x++)
+ {
+ CannyInfo
+ pixel;
+
+ register const Quantum
+ *restrict kernel_pixels;
+
+ ssize_t
+ v;
+
+ static double
+ Gx[3][3] =
+ {
+ { -1.0, 0.0, +1.0 },
+ { -2.0, 0.0, +2.0 },
+ { -1.0, 0.0, +1.0 }
+ },
+ Gy[3][3] =
+ {
+ { +1.0, +2.0, +1.0 },
+ { 0.0, 0.0, 0.0 },
+ { -1.0, -2.0, -1.0 }
+ };
+
+ (void) ResetMagickMemory(&pixel,0,sizeof(pixel));
+ kernel_pixels=p;
+ for (v=0; v < 3; v++)
+ {
+ ssize_t
+ u;
+
+ for (u=0; u < 3; u++)
+ {
+ double
+ intensity;
+
+ intensity=GetPixelIntensity(edge_image,kernel_pixels+u);
+ pixel.Dx+=Gx[v][u]*intensity;
+ pixel.Dy+=Gy[v][u]*intensity;
+ }
+ kernel_pixels+=edge_image->columns+2;
+ }
+ pixel.magnitude=sqrt(pixel.Dx*pixel.Dx+pixel.Dy*pixel.Dy);
+ if (SetMatrixElement(pixel_cache,x,y,&pixel) == MagickFalse)
+ continue;
+ p+=GetPixelChannels(edge_image);
+ }
+ }
+ edge_view=DestroyCacheView(edge_view);
+ /*
+ Non-maxima suppression; reset edge image.
+ */
+ histogram=(size_t *) AcquireQuantumMemory(65536,sizeof(*histogram));
+ if (histogram == (size_t *) NULL)
+ {
+ pixel_cache=DestroyMatrixInfo(pixel_cache);
+ edge_image=DestroyImage(edge_image);
+ return((Image *) NULL);
+ }
+ (void) ResetMagickMemory(histogram,0,65536*sizeof(*histogram));
+ edge_view=AcquireAuthenticCacheView(edge_image,exception);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+ #pragma omp parallel for schedule(static,4) shared(status) \
+ magick_threads(edge_image,edge_image,edge_image->rows,1)
+#endif
+ for (y=0; y < (ssize_t) edge_image->rows; y++)
+ {
+ register Quantum
+ *restrict q;
+
+ register ssize_t
+ x;
+
+ if (status == MagickFalse)
+ continue;
+ q=GetCacheViewAuthenticPixels(edge_view,0,y,edge_image->columns,1,
+ exception);
+ if (q == (Quantum *) NULL)
+ {
+ status=MagickFalse;
+ continue;
+ }
+ for (x=0; x < (ssize_t) edge_image->columns; x++)
+ {
+ CannyInfo
+ alpha_pixel,
+ beta_pixel,
+ pixel;
+
+ ssize_t
+ direction;
+
+ (void) GetMatrixElement(pixel_cache,x,y,&pixel);
+ direction=2;
+ if (pixel.Dx != 0.0)
+ {
+ double
+ sector;
+
+ sector=pixel.Dy/pixel.Dx;
+ if (sector < 0.0)
+ {
+ if (sector < -2.41421356237)
+ direction=0;
+ else
+ if (sector < -0.414213562373)
+ direction=1;
+ else
+ direction=2;
+ }
+ else
+ {
+ if (sector > 2.41421356237)
+ direction=0;
+ else
+ if (sector > 0.414213562373)
+ direction=3;
+ else
+ direction=2;
+ }
+ }
+ switch (direction)
+ {
+ case 0:
+ {
+ /*
+ 0 degrees.
+ */
+ (void) GetMatrixElement(pixel_cache,x,y-1,&alpha_pixel);
+ (void) GetMatrixElement(pixel_cache,x,y+1,&beta_pixel);
+ break;
+ }
+ case 1:
+ {
+ /*
+ 45 degrees.
+ */
+ (void) GetMatrixElement(pixel_cache,x-1,y-1,&alpha_pixel);
+ (void) GetMatrixElement(pixel_cache,x+1,y+1,&beta_pixel);
+ break;
+ }
+ case 2:
+ {
+ /*
+ 90 degrees.
+ */
+ (void) GetMatrixElement(pixel_cache,x-1,y,&alpha_pixel);
+ (void) GetMatrixElement(pixel_cache,x+1,y,&beta_pixel);
+ }
+ case 3:
+ {
+ /*
+ 135 degrees.
+ */
+ (void) GetMatrixElement(pixel_cache,x+1,y-1,&alpha_pixel);
+ (void) GetMatrixElement(pixel_cache,x-1,y+1,&beta_pixel);
+ }
+ }
+ pixel.intensity=pixel.magnitude;
+ if ((pixel.magnitude < alpha_pixel.magnitude) ||
+ (pixel.magnitude < beta_pixel.magnitude))
+ pixel.intensity=0;
+ else
+ if (pixel.magnitude > QuantumRange)
+ pixel.intensity=QuantumRange;
+ (void) SetMatrixElement(pixel_cache,x,y,&pixel);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+ #pragma omp critical (MagickCore_CannyEdgeImage)
+#endif
+ histogram[ScaleQuantumToShort(ClampToQuantum(pixel.intensity))]++;
+ *q=0;
+ q+=GetPixelChannels(edge_image);
+ }
+ if (SyncCacheViewAuthenticPixels(edge_view,exception) == MagickFalse)
+ status=MagickFalse;
+ }
+ edge_view=DestroyCacheView(edge_view);
+ /*
+ Estimate hysteresis threshold.
+ */
+ number_pixels=(size_t) (low_percent*(image->columns*image->rows-
+ histogram[0]));
+ count=0;
+ for (i=65535; count < (ssize_t) number_pixels; i--)
+ count+=histogram[i];
+ high_threshold=(double) ScaleShortToQuantum((unsigned short) i);
+ for (i=0; histogram[i] == 0; i++) ;
+ low_threshold=high_percent*(high_threshold+
+ ScaleShortToQuantum((unsigned short) i));
+ histogram=(size_t *) RelinquishMagickMemory(histogram);
+ /*
+ Hysteresis thresholding.
+ */
+ edge_view=AcquireAuthenticCacheView(edge_image,exception);
+#if defined(MAGICKCORE_OPENMP_SUPPORT)
+ #pragma omp parallel for schedule(static,4) shared(status) \
+ magick_threads(edge_image,edge_image,edge_image->rows,1)
+#endif
+ for (y=0; y < (ssize_t) edge_image->rows; y++)
+ {
+ register Quantum
+ *restrict q;
+
+ register ssize_t
+ x;
+
+ if (status == MagickFalse)
+ continue;
+ q=GetCacheViewAuthenticPixels(edge_view,0,y,edge_image->columns,1,
+ exception);
+ if (q == (Quantum *) NULL)
+ {
+ status=MagickFalse;
+ continue;
+ }
+ for (x=0; x < (ssize_t) edge_image->columns; x++)
+ {
+ CannyInfo
+ pixel;
+
+ (void) GetMatrixElement(pixel_cache,x,y,&pixel);
+ if (pixel.intensity >= high_threshold)
+ (void) TraceEdge(edge_image,edge_view,pixel_cache,x,y,low_threshold,
+ exception);
+ }
+ if (SyncCacheViewAuthenticPixels(edge_view,exception) == MagickFalse)
+ status=MagickFalse;
+ }
+ edge_view=DestroyCacheView(edge_view);
+ pixel_cache=DestroyMatrixInfo(pixel_cache);
return(edge_image);
}
\f
projects / imagemagick / commitdiff