//
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// GPUImageHistogramEqualizationFilter.m
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// FilterShowcase
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//
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// Created by Adam Marcus on 19/08/2014.
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// Copyright (c) 2014 Sunset Lake Software LLC. All rights reserved.
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//
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#import "GPUImageHistogramEqualizationFilter.h"
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageRedHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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lowp float redCurveValue = texture2D(inputImageTexture2, vec2(textureColor.r, 0.0)).r;
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gl_FragColor = vec4(redCurveValue, textureColor.g, textureColor.b, textureColor.a);
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}
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);
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#else
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NSString *const kGPUImageRedHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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float redCurveValue = texture2D(inputImageTexture2, vec2(textureColor.r, 0.0)).r;
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gl_FragColor = vec4(redCurveValue, textureColor.g, textureColor.b, textureColor.a);
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}
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);
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#endif
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageGreenHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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lowp float greenCurveValue = texture2D(inputImageTexture2, vec2(textureColor.g, 0.0)).g;
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gl_FragColor = vec4(textureColor.r, greenCurveValue, textureColor.b, textureColor.a);
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}
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);
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#else
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NSString *const kGPUImageGreenHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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float greenCurveValue = texture2D(inputImageTexture2, vec2(textureColor.g, 0.0)).g;
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gl_FragColor = vec4(textureColor.r, greenCurveValue, textureColor.b, textureColor.a);
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}
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);
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#endif
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageBlueHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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lowp float blueCurveValue = texture2D(inputImageTexture2, vec2(textureColor.b, 0.0)).b;
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gl_FragColor = vec4(textureColor.r, textureColor.g, blueCurveValue, textureColor.a);
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}
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);
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#else
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NSString *const kGPUImageBlueHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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float blueCurveValue = texture2D(inputImageTexture2, vec2(textureColor.b, 0.0)).b;
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gl_FragColor = vec4(textureColor.r, textureColor.g, blueCurveValue, textureColor.a);
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}
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);
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#endif
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageRGBHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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lowp float redCurveValue = texture2D(inputImageTexture2, vec2(textureColor.r, 0.0)).r;
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lowp float greenCurveValue = texture2D(inputImageTexture2, vec2(textureColor.g, 0.0)).g;
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lowp float blueCurveValue = texture2D(inputImageTexture2, vec2(textureColor.b, 0.0)).b;
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gl_FragColor = vec4(redCurveValue, greenCurveValue, blueCurveValue, textureColor.a);
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}
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);
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#else
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NSString *const kGPUImageRGBHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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float redCurveValue = texture2D(inputImageTexture2, vec2(textureColor.r, 0.0)).r;
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float greenCurveValue = texture2D(inputImageTexture2, vec2(textureColor.g, 0.0)).g;
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float blueCurveValue = texture2D(inputImageTexture2, vec2(textureColor.b, 0.0)).b;
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gl_FragColor = vec4(redCurveValue, greenCurveValue, blueCurveValue, textureColor.a);
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}
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);
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#endif
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageLuminanceHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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const lowp vec3 W = vec3(0.2125, 0.7154, 0.0721);
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void main()
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{
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lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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lowp float luminance = dot(textureColor.rgb, W);
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lowp float newLuminance = texture2D(inputImageTexture2, vec2(luminance, 0.0)).r;
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lowp float deltaLuminance = newLuminance - luminance;
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lowp float red = clamp(textureColor.r + deltaLuminance, 0.0, 1.0);
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lowp float green = clamp(textureColor.g + deltaLuminance, 0.0, 1.0);
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lowp float blue = clamp(textureColor.b + deltaLuminance, 0.0, 1.0);
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gl_FragColor = vec4(red, green, blue, textureColor.a);
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}
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);
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#else
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NSString *const kGPUImageLuminanceHistogramEqualizationFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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const vec3 W = vec3(0.2125, 0.7154, 0.0721);
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void main()
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{
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vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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float luminance = dot(textureColor.rgb, W);
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float newLuminance = texture2D(inputImageTexture2, vec2(luminance, 0.0)).r;
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float deltaLuminance = newLuminance - luminance;
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float red = clamp(textureColor.r + deltaLuminance, 0.0, 1.0);
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float green = clamp(textureColor.g + deltaLuminance, 0.0, 1.0);
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float blue = clamp(textureColor.b + deltaLuminance, 0.0, 1.0);
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gl_FragColor = vec4(red, green, blue, textureColor.a);
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}
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);
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#endif
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@implementation GPUImageHistogramEqualizationFilter
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@synthesize downsamplingFactor = _downsamplingFactor;
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#pragma mark -
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#pragma mark Initialization
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- (id)init;
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{
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if (!(self = [self initWithHistogramType:kGPUImageHistogramRGB]))
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{
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return nil;
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}
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return self;
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}
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- (id)initWithHistogramType:(GPUImageHistogramType)newHistogramType
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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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histogramFilter = [[GPUImageHistogramFilter alloc] initWithHistogramType:newHistogramType];
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[self addFilter:histogramFilter];
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GLubyte dummyInput[4 * 256]; // NB: No way to initialise GPUImageRawDataInput without providing bytes
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rawDataInputFilter = [[GPUImageRawDataInput alloc] initWithBytes:dummyInput size:CGSizeMake(256.0, 1.0) pixelFormat:GPUPixelFormatBGRA type:GPUPixelTypeUByte];
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rawDataOutputFilter = [[GPUImageRawDataOutput alloc] initWithImageSize:CGSizeMake(256.0, 3.0) resultsInBGRAFormat:YES];
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__unsafe_unretained GPUImageRawDataOutput *_rawDataOutputFilter = rawDataOutputFilter;
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__unsafe_unretained GPUImageRawDataInput *_rawDataInputFilter = rawDataInputFilter;
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[rawDataOutputFilter setNewFrameAvailableBlock:^{
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unsigned int histogramBins[3][256];
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[_rawDataOutputFilter lockFramebufferForReading];
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GLubyte *data = [_rawDataOutputFilter rawBytesForImage];
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data += [_rawDataOutputFilter bytesPerRowInOutput];
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histogramBins[0][0] = *data++;
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histogramBins[1][0] = *data++;
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histogramBins[2][0] = *data++;
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data++;
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for (unsigned int x = 1; x < 256; x++) {
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histogramBins[0][x] = histogramBins[0][x-1] + *data++;
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histogramBins[1][x] = histogramBins[1][x-1] + *data++;
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histogramBins[2][x] = histogramBins[2][x-1] + *data++;
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data++;
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}
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[_rawDataOutputFilter unlockFramebufferAfterReading];
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GLubyte colorMapping[4 * 256];
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GLubyte *_colorMapping = colorMapping;
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for (unsigned int x = 0; x < 256; x++) {
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*_colorMapping++ = (GLubyte) (((histogramBins[0][x] - histogramBins[0][0]) * 255) / histogramBins[0][255]);
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*_colorMapping++ = (GLubyte) (((histogramBins[1][x] - histogramBins[1][0]) * 255) / histogramBins[1][255]);
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*_colorMapping++ = (GLubyte) (((histogramBins[2][x] - histogramBins[2][0]) * 255) / histogramBins[2][255]);
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*_colorMapping++ = 255;
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}
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_colorMapping = colorMapping;
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[_rawDataInputFilter updateDataFromBytes:_colorMapping size:CGSizeMake(256.0, 1.0)];
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[_rawDataInputFilter processData];
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}];
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[histogramFilter addTarget:rawDataOutputFilter];
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NSString *fragmentShader = nil;
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switch (newHistogramType) {
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case kGPUImageHistogramRed:
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fragmentShader = kGPUImageRedHistogramEqualizationFragmentShaderString;
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break;
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case kGPUImageHistogramGreen:
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fragmentShader = kGPUImageGreenHistogramEqualizationFragmentShaderString;
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break;
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case kGPUImageHistogramBlue:
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fragmentShader = kGPUImageBlueHistogramEqualizationFragmentShaderString;
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break;
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default:
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case kGPUImageHistogramRGB:
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fragmentShader = kGPUImageRGBHistogramEqualizationFragmentShaderString;
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break;
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case kGPUImageHistogramLuminance:
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fragmentShader = kGPUImageLuminanceHistogramEqualizationFragmentShaderString;
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break;
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}
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GPUImageFilter *equalizationFilter = [[GPUImageTwoInputFilter alloc] initWithFragmentShaderFromString:fragmentShader];
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[rawDataInputFilter addTarget:equalizationFilter atTextureLocation:1];
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[self addFilter:equalizationFilter];
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self.initialFilters = [NSArray arrayWithObjects:histogramFilter, equalizationFilter, nil];
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self.terminalFilter = equalizationFilter;
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self.downsamplingFactor = 16;
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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)setDownsamplingFactor:(NSUInteger)newValue;
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{
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if (_downsamplingFactor != newValue)
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{
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_downsamplingFactor = newValue;
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histogramFilter.downsamplingFactor = newValue;
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}
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}
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@end
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