IOS OpenGL ES GPUImage 图像阈值边缘检测GPUImageThresholdEdgeDetectionF ...

目录

• 一.简介
  
• 二.效果演示
  
• 三.源码下载
  
• 四.猜你喜欢
  

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零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES GPUImage 使用
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一.简介

GPUImage 共 125 个滤镜, 分为四类

1、Color adjustments : 31 filters , 颜色处理相关
2、Image processing : 40 filters , 图像处理相关.
3、Blending modes : 29 filters , 混合模式相关.
4、Visual effects : 25 filters , 视觉效果相关.

GPUImageThresholdEdgeDetectionFilter 属于 GPUImage 图像视觉效果相关，用于图像阈值边缘检测。shader 源码如下：

1. /******************************************************************************************/
2. //@Author:猿说编程
3. //@Blog(个人博客地址): www.codersrc.com
4. //@File:IOS – OpenGL ES GPUImage GPUImageThresholdEdgeDetectionFilter
5. //@Time:2022/06/26 06:30
6. //@Motto:不积跬步无以至千里，不积小流无以成江海，程序人生的精彩需要坚持不懈地积累！
7. /******************************************************************************************/
9. // Invert the colorspace for a sketch
10. #if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
11. NSString *const kGPUImageThresholdEdgeDetectionFragmentShaderString = SHADER_STRING
12. (
13. precision highp float;
15. varying vec2 textureCoordinate;
16. varying vec2 leftTextureCoordinate;
17. varying vec2 rightTextureCoordinate;
19. varying vec2 topTextureCoordinate;
20. varying vec2 topLeftTextureCoordinate;
21. varying vec2 topRightTextureCoordinate;
23. varying vec2 bottomTextureCoordinate;
24. varying vec2 bottomLeftTextureCoordinate;
25. varying vec2 bottomRightTextureCoordinate;
27. uniform sampler2D inputImageTexture;
28. uniform lowp float threshold;
30. uniform float edgeStrength;
32. void main()
33. {
34. //     float bottomLeftIntensity = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
35. //     float topRightIntensity = texture2D(inputImageTexture, topRightTextureCoordinate).r;
36. //     float topLeftIntensity = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
37. //     float bottomRightIntensity = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
38.      float leftIntensity = texture2D(inputImageTexture, leftTextureCoordinate).r;
39.      float rightIntensity = texture2D(inputImageTexture, rightTextureCoordinate).r;
40.      float bottomIntensity = texture2D(inputImageTexture, bottomTextureCoordinate).r;
41.      float topIntensity = texture2D(inputImageTexture, topTextureCoordinate).r;
42.      float centerIntensity = texture2D(inputImageTexture, textureCoordinate).r;
43. //     float h = -topLeftIntensity - 2.0 * topIntensity - topRightIntensity + bottomLeftIntensity + 2.0 * bottomIntensity + bottomRightIntensity;
44. //     float v = -bottomLeftIntensity - 2.0 * leftIntensity - topLeftIntensity + bottomRightIntensity + 2.0 * rightIntensity + topRightIntensity;
45. //     float h = -topLeftIntensity - 2.0 * topIntensity - topRightIntensity + leftIntensity + 2.0 * centerIntensity + rightIntensity;
46. //     float v = -bottomLeftIntensity - 2.0 * leftIntensity - topLeftIntensity + bottomIntensity + 2.0 * centerIntensity + topIntensity;
47.      float h = (centerIntensity - topIntensity) + (bottomIntensity - centerIntensity);
48.      float v = (centerIntensity - leftIntensity) + (rightIntensity - centerIntensity);
49. //     float h = (centerIntensity - topIntensity);
50. //     float j = (topIntensity - centerIntensity);
51. //     h = max(h,j);
52. //     j = abs(h);
53. //     float v = (centerIntensity - leftIntensity);
55.     float mag = length(vec2(h, v)) * edgeStrength;
56.      mag = step(threshold, mag);
58. //     float mag = abs(h);
60. //     gl_FragColor = vec4(h, h, h, 1.0);
61. //     gl_FragColor = vec4(texture2D(inputImageTexture, textureCoordinate));
62. //     gl_FragColor = vec4(h, centerIntensity, j, 1.0);
63.      gl_FragColor = vec4(mag, mag, mag, 1.0);
64. }
65. );
66. #else
67. NSString *const kGPUImageThresholdEdgeDetectionFragmentShaderString = SHADER_STRING
68. (
69. varying vec2 textureCoordinate;
70. varying vec2 leftTextureCoordinate;
71. varying vec2 rightTextureCoordinate;
73. varying vec2 topTextureCoordinate;
74. varying vec2 topLeftTextureCoordinate;
75. varying vec2 topRightTextureCoordinate;
77. varying vec2 bottomTextureCoordinate;
78. varying vec2 bottomLeftTextureCoordinate;
79. varying vec2 bottomRightTextureCoordinate;
81. uniform sampler2D inputImageTexture;
82. uniform float threshold;
84. uniform float edgeStrength;
86. void main()
87. {
88.      float bottomLeftIntensity = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
89.      float topRightIntensity = texture2D(inputImageTexture, topRightTextureCoordinate).r;
90.      float topLeftIntensity = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
91.      float bottomRightIntensity = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
92.      float leftIntensity = texture2D(inputImageTexture, leftTextureCoordinate).r;
93.      float rightIntensity = texture2D(inputImageTexture, rightTextureCoordinate).r;
94.      float bottomIntensity = texture2D(inputImageTexture, bottomTextureCoordinate).r;
95.      float topIntensity = texture2D(inputImageTexture, topTextureCoordinate).r;
96.      float h = -topLeftIntensity - 2.0 * topIntensity - topRightIntensity + bottomLeftIntensity + 2.0 * bottomIntensity + bottomRightIntensity;
97.      h = max(0.0, h);
98.      float v = -bottomLeftIntensity - 2.0 * leftIntensity - topLeftIntensity + bottomRightIntensity + 2.0 * rightIntensity + topRightIntensity;
99.      v = max(0.0, v);
101.      float mag = length(vec2(h, v)) * edgeStrength;
102.      mag = step(threshold, mag);
104.      gl_FragColor = vec4(vec3(mag), 1.0);
105. }
106. );
107. #endif

复制代码

二.效果演示

使用 GPUImageThresholdEdgeDetectionFilter **,**原图如下：

使用 GPUImageThresholdEdgeDetectionFilter 效果如下：

三.源码下载

OpenGL ES Demo 下载地址 : IOS OpenGL ES GPUImage 图像阈值边缘检测 GPUImageThresholdEdgeDetectionFilter

四.猜你喜欢

• IOS OPenGL ES 设置图像亮度 GPUImageBrightnessFilter
  
• IOS OPenGL ES 调节图像曝光度 GPUImageExposureFilter
  
• IOS OpenGL ES 调节图像对比度 GPUImageContrastFilter
  
• IOS OPenGL ES 调节图像饱和度 GPUImageSaturationFilter
  
• IOS OPenGL ES 调节图像伽马线 GPUImageGammaFilter
  
• IOS OpenGL ES 调节图像反色 GPUImageColorInvertFilter
  
• IOS OpenGL ES 调节图像褐色 GPUImageSepiaFilter
  
• IOS OpenGL ES 调节图像灰色 GPUImageGrayscaleFilter
  
• IOS OpenGL ES 调节图像 RGB 通道 GPUImageRGBFilter
  
• IOS OpenGL ES 调节图像不透明度 GPUImageOpacityFilter
  
• IOS OpenGL ES 调节图像阴影 GPUImageHighlightShadowFilter
  
• IOS OpenGL ES 调节图像色彩替换 GPUImageFalseColorFilter
  
• GPUImage – 色彩直方图 GPUImageHistogramFilter
  
• GPUImage – 色彩直方图 GPUImageHistogramGenerator
  
• GPUImage – 像素平均色值 GPUImageAverageColor
  
• GPUImage – 亮度平均 GPUImageLuminosity
  
• IOS OpenGL ES 调节图像色度 GPUImageHueFilter
  
• IOS OpenGL ES 指定颜色抠图 GPUImageChromaKeyFilter
  
• IOS OpenGL ES 调节图像白平衡/色温 GPUImageWhiteBalanceFilter
  
• IOS OpenGL ES 设置图像 lookup 滤镜 GPUImageLookupFilter
  
• IOS OpenGL ES 设置图像滤镜 GPUImageAmatorkaFilter
  
• IOS OpenGL ES 设置图像滤镜 GPUImageSoftEleganceFilter
  
• IOS OpenGL ES 设置图像锐化 GPUImageSharpenFilter
  
• IOS OpenGL ES 绘制十字 GPUImageCrosshairGenerator
  
• IOS OpenGL ES 绘制线条 GPUImageLineGenerator
  
• IOS OpenGL ES 设置图像黑白燥点 GPUImageLocalBinaryPatternFilter
  
• IOS OpenGL ES 设置图像卡通效果（黑色粗线描边） GPUImageToonFilter
  
• IOS OpenGL ES 桑原滤波/水粉画模糊效果 GPUImageKuwaharaFilter
  
• IOS OpenGL ES 黑白马赛克效果 GPUImageMosaicFilter
  
• IOS OpenGL ES 像素化马赛克效果 GPUImagePixellateFilter
  
• IOS OpenGL ES 同心圆像素化马赛克效果 GPUImagePolarPixel
  
• IOS OpenGL ES 黑白网状效果 GPUImageCrosshatchFilter
  
• IOS OpenGL ES 色彩丢失/模糊效果 GPUImageColorPackingFilter
  
• IOS OpenGL ES 图像晕影 GPUImageVignetteFilter
  
• IOS OpenGL ES 图像漩涡 GPUImageSwirlFilter
  
• IOS OpenGL ES 图像鱼眼扩散效果 GPUImageBulgeDistortionFilter
  
• IOS OpenGL ES 图像鱼眼移动效果 GPUImageBulgeDistortionFilter
  
• IOS OpenGL ES 图像凹面镜移动效果 GPUImagePinchDistortionFilter
  
• IOS OpenGL ES 图像凹面镜放大效果 GPUImagePinchDistortionFilter
  
• IOS OpenGL ES 图像哈哈镜效果 GPUImageStretchDistortionFilter
  
• IOS OpenGL ES 图像水晶球效果 GPUImageGlassSphereFilter
  
• IOS OpenGL ES 图像球形折射 GPUImageSphereRefractionFilter
  
• IOS OpenGL ES 图像色调分离噪点效果 GPUImagePosterizeFilter
  
• IOS OpenGL ES 图像 CGA 色彩滤镜 GPUImageCGAColorspaceFilter
  
• IOS OpenGL ES 图像柏林噪点/花边噪点 GPUImagePerlinNoiseFilter
  
• IOS OpenGL ES 图像加亮边缘 GPUImage3x3ConvolutionFilter
  
• IOS OpenGL ES 图像浮雕 3d 效果 GPUImageEmbossFilter
  
• IOS OpenGL ES 图像马赛克圆点 GPUImagePolkaDotFilter
  
• IOS OpenGL ES 图像侵蚀边缘黑白模糊 GPUImageErosionFilter
  
• IOS OpenGL ES 图像侵蚀边缘色彩模糊 GPUImageRGBErosionFilter
  
• IOS OpenGL ES 图像扩展边缘黑白模糊 GPUImageDilationFilter
  
• IOS OpenGL ES 图像扩展边缘彩色模糊 GPUImageRGBDilationFilter
  
• IOS OpenGL ES GPUImage 黑白色调模糊 GPUImageOpeningFilter
  
• IOS OpenGL ES GPUImage 彩色模糊 GPUImageRGBOpeningFilter
  
• IOS OpenGL ES GPUImage 图像黑白色调模糊/暗色提亮 GPUImageClosingFilter
  
• IOS OpenGL ES GPUImage 图像彩色调模糊/暗色提亮 GPUImageRGBClosingFilter
  
• IOS OpenGL ES GPUImage 图像 Lanczos 重取样模糊效果 GPUImageLanczosResamplingFilter
  
• IOS OpenGL ES GPUImage 图像显示亮度最高的像素,其他为黑 GPUImageNonMaximumSuppressionFilter
  
• IOS OpenGL ES GPUImage 图像显示亮度最高的像素,其他为黑 GPUImageThresholdedNonMaximumSuppressionFilter
  
• IOS OpenGL ES GPUImage 图像 Sobel 边缘检测，类似漫画反色 GPUImageSobelEdgeDetectionFilter
  
• IOS OpenGL ES GPUImage GPUImageWeakPixelInclusionFilter
  
• IOS OpenGL ES GPUImage GPUImageDirectionalNonMaximumSuppressionFilter
  
• IOS OpenGL ES GPUImage 图像阈值边缘检测 GPUImageThresholdEdgeDetectionFilter
  

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