#import "GPUImageSaturationBlendFilter.h"
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/**
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* Saturation blend mode based upon pseudo code from the PDF specification.
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*/
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageSaturationBlendFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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varying highp vec2 textureCoordinate2;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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highp float lum(lowp vec3 c) {
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return dot(c, vec3(0.3, 0.59, 0.11));
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}
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lowp vec3 clipcolor(lowp vec3 c) {
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highp float l = lum(c);
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lowp float n = min(min(c.r, c.g), c.b);
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lowp float x = max(max(c.r, c.g), c.b);
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if (n < 0.0) {
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c.r = l + ((c.r - l) * l) / (l - n);
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c.g = l + ((c.g - l) * l) / (l - n);
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c.b = l + ((c.b - l) * l) / (l - n);
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}
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if (x > 1.0) {
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c.r = l + ((c.r - l) * (1.0 - l)) / (x - l);
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c.g = l + ((c.g - l) * (1.0 - l)) / (x - l);
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c.b = l + ((c.b - l) * (1.0 - l)) / (x - l);
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}
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return c;
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}
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lowp vec3 setlum(lowp vec3 c, highp float l) {
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highp float d = l - lum(c);
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c = c + vec3(d);
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return clipcolor(c);
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}
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highp float sat(lowp vec3 c) {
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lowp float n = min(min(c.r, c.g), c.b);
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lowp float x = max(max(c.r, c.g), c.b);
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return x - n;
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}
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lowp float mid(lowp float cmin, lowp float cmid, lowp float cmax, highp float s) {
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return ((cmid - cmin) * s) / (cmax - cmin);
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}
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lowp vec3 setsat(lowp vec3 c, highp float s) {
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if (c.r > c.g) {
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if (c.r > c.b) {
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if (c.g > c.b) {
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/* g is mid, b is min */
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c.g = mid(c.b, c.g, c.r, s);
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c.b = 0.0;
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} else {
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/* b is mid, g is min */
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c.b = mid(c.g, c.b, c.r, s);
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c.g = 0.0;
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}
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c.r = s;
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} else {
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/* b is max, r is mid, g is min */
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c.r = mid(c.g, c.r, c.b, s);
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c.b = s;
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c.r = 0.0;
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}
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} else if (c.r > c.b) {
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/* g is max, r is mid, b is min */
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c.r = mid(c.b, c.r, c.g, s);
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c.g = s;
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c.b = 0.0;
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} else if (c.g > c.b) {
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/* g is max, b is mid, r is min */
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c.b = mid(c.r, c.b, c.g, s);
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c.g = s;
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c.r = 0.0;
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} else if (c.b > c.g) {
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/* b is max, g is mid, r is min */
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c.g = mid(c.r, c.g, c.b, s);
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c.b = s;
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c.r = 0.0;
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} else {
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c = vec3(0.0);
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}
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return c;
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}
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void main()
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{
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highp vec4 baseColor = texture2D(inputImageTexture, textureCoordinate);
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highp vec4 overlayColor = texture2D(inputImageTexture2, textureCoordinate2);
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gl_FragColor = vec4(baseColor.rgb * (1.0 - overlayColor.a) + setlum(setsat(baseColor.rgb, sat(overlayColor.rgb)), lum(baseColor.rgb)) * overlayColor.a, baseColor.a);
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}
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);
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#else
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NSString *const kGPUImageSaturationBlendFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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varying vec2 textureCoordinate2;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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float lum(vec3 c) {
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return dot(c, vec3(0.3, 0.59, 0.11));
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}
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vec3 clipcolor(vec3 c) {
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float l = lum(c);
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float n = min(min(c.r, c.g), c.b);
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float x = max(max(c.r, c.g), c.b);
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if (n < 0.0) {
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c.r = l + ((c.r - l) * l) / (l - n);
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c.g = l + ((c.g - l) * l) / (l - n);
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c.b = l + ((c.b - l) * l) / (l - n);
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}
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if (x > 1.0) {
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c.r = l + ((c.r - l) * (1.0 - l)) / (x - l);
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c.g = l + ((c.g - l) * (1.0 - l)) / (x - l);
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c.b = l + ((c.b - l) * (1.0 - l)) / (x - l);
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}
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return c;
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}
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vec3 setlum(vec3 c, float l) {
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float d = l - lum(c);
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c = c + vec3(d);
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return clipcolor(c);
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}
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float sat(vec3 c) {
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float n = min(min(c.r, c.g), c.b);
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float x = max(max(c.r, c.g), c.b);
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return x - n;
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}
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float mid(float cmin, float cmid, float cmax, float s) {
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return ((cmid - cmin) * s) / (cmax - cmin);
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}
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vec3 setsat(vec3 c, float s) {
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if (c.r > c.g) {
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if (c.r > c.b) {
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if (c.g > c.b) {
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/* g is mid, b is min */
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c.g = mid(c.b, c.g, c.r, s);
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c.b = 0.0;
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} else {
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/* b is mid, g is min */
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c.b = mid(c.g, c.b, c.r, s);
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c.g = 0.0;
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}
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c.r = s;
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} else {
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/* b is max, r is mid, g is min */
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c.r = mid(c.g, c.r, c.b, s);
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c.b = s;
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c.r = 0.0;
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}
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} else if (c.r > c.b) {
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/* g is max, r is mid, b is min */
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c.r = mid(c.b, c.r, c.g, s);
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c.g = s;
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c.b = 0.0;
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} else if (c.g > c.b) {
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/* g is max, b is mid, r is min */
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c.b = mid(c.r, c.b, c.g, s);
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c.g = s;
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c.r = 0.0;
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} else if (c.b > c.g) {
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/* b is max, g is mid, r is min */
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c.g = mid(c.r, c.g, c.b, s);
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c.b = s;
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c.r = 0.0;
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} else {
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c = vec3(0.0);
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}
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return c;
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}
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void main()
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{
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vec4 baseColor = texture2D(inputImageTexture, textureCoordinate);
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vec4 overlayColor = texture2D(inputImageTexture2, textureCoordinate2);
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gl_FragColor = vec4(baseColor.rgb * (1.0 - overlayColor.a) + setlum(setsat(baseColor.rgb, sat(overlayColor.rgb)), lum(baseColor.rgb)) * overlayColor.a, baseColor.a);
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}
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);
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#endif
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@implementation GPUImageSaturationBlendFilter
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- (id)init;
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{
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if (!(self = [super initWithFragmentShaderFromString:kGPUImageSaturationBlendFragmentShaderString]))
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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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@end
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