#import "GPUImageCannyEdgeDetectionFilter.h"
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#import "GPUImageGrayscaleFilter.h"
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#import "GPUImageDirectionalSobelEdgeDetectionFilter.h"
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#import "GPUImageDirectionalNonMaximumSuppressionFilter.h"
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#import "GPUImageWeakPixelInclusionFilter.h"
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#import "GPUImageSingleComponentGaussianBlurFilter.h"
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@implementation GPUImageCannyEdgeDetectionFilter
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@synthesize upperThreshold;
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@synthesize lowerThreshold;
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@synthesize blurRadiusInPixels;
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@synthesize blurTexelSpacingMultiplier;
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@synthesize texelWidth;
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@synthesize texelHeight;
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- (id)init;
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{
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if (!(self = [super init]))
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{
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return nil;
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}
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// First pass: convert image to luminance
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luminanceFilter = [[GPUImageGrayscaleFilter alloc] init];
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[self addFilter:luminanceFilter];
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// Second pass: apply a variable Gaussian blur
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blurFilter = [[GPUImageSingleComponentGaussianBlurFilter alloc] init];
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[self addFilter:blurFilter];
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// Third pass: run the Sobel edge detection, with calculated gradient directions, on this blurred image
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edgeDetectionFilter = [[GPUImageDirectionalSobelEdgeDetectionFilter alloc] init];
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[self addFilter:edgeDetectionFilter];
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// Fourth pass: apply non-maximum suppression
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nonMaximumSuppressionFilter = [[GPUImageDirectionalNonMaximumSuppressionFilter alloc] init];
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[self addFilter:nonMaximumSuppressionFilter];
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// Fifth pass: include weak pixels to complete edges
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weakPixelInclusionFilter = [[GPUImageWeakPixelInclusionFilter alloc] init];
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[self addFilter:weakPixelInclusionFilter];
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[luminanceFilter addTarget:blurFilter];
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[blurFilter addTarget:edgeDetectionFilter];
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[edgeDetectionFilter addTarget:nonMaximumSuppressionFilter];
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[nonMaximumSuppressionFilter addTarget:weakPixelInclusionFilter];
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self.initialFilters = [NSArray arrayWithObject:luminanceFilter];
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// self.terminalFilter = nonMaximumSuppressionFilter;
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self.terminalFilter = weakPixelInclusionFilter;
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self.blurRadiusInPixels = 2.0;
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self.blurTexelSpacingMultiplier = 1.0;
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self.upperThreshold = 0.4;
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self.lowerThreshold = 0.1;
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return self;
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}
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#pragma mark -
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#pragma mark Accessors
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- (void)setBlurRadiusInPixels:(CGFloat)newValue;
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{
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blurFilter.blurRadiusInPixels = newValue;
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}
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- (CGFloat)blurRadiusInPixels;
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{
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return blurFilter.blurRadiusInPixels;
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}
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- (void)setBlurTexelSpacingMultiplier:(CGFloat)newValue;
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{
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blurFilter.texelSpacingMultiplier = newValue;
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}
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- (CGFloat)blurTexelSpacingMultiplier;
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{
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return blurFilter.texelSpacingMultiplier;
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}
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- (void)setTexelWidth:(CGFloat)newValue;
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{
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edgeDetectionFilter.texelWidth = newValue;
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}
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- (CGFloat)texelWidth;
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{
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return edgeDetectionFilter.texelWidth;
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}
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- (void)setTexelHeight:(CGFloat)newValue;
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{
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edgeDetectionFilter.texelHeight = newValue;
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}
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- (CGFloat)texelHeight;
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{
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return edgeDetectionFilter.texelHeight;
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}
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- (void)setUpperThreshold:(CGFloat)newValue;
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{
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nonMaximumSuppressionFilter.upperThreshold = newValue;
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}
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- (CGFloat)upperThreshold;
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{
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return nonMaximumSuppressionFilter.upperThreshold;
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}
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- (void)setLowerThreshold:(CGFloat)newValue;
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{
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nonMaximumSuppressionFilter.lowerThreshold = newValue;
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}
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- (CGFloat)lowerThreshold;
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{
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return nonMaximumSuppressionFilter.lowerThreshold;
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}
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@end
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