目录

• 一.简介
• 二.效果演示
• 三.源码下载
• 四.猜你喜欢

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 基础

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 转场

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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

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES GLSL 编程

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.

GPUImageKuwaharaFilter GPUImage 图像桑原滤波/水粉画模糊效果，shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 桑原滤波/水粉画模糊效果 GPUImageKuwaharaFilter
//@Time:2022/05/15 10:30
//@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！
/******************************************************************************************/
#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImageKuwaharaFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;
 uniform sampler2D inputImageTexture;
 uniform int radius;

 precision highp float;

 const vec2 src_size = vec2 (1.0 / 768.0, 1.0 / 1024.0);

 void main (void)
 {
     vec2 uv = textureCoordinate;
     float n = float((radius + 1) * (radius + 1));
     int i; int j;
     vec3 m0 = vec3(0.0); vec3 m1 = vec3(0.0); vec3 m2 = vec3(0.0); vec3 m3 = vec3(0.0);
     vec3 s0 = vec3(0.0); vec3 s1 = vec3(0.0); vec3 s2 = vec3(0.0); vec3 s3 = vec3(0.0);
     vec3 c;

     for (j = -radius; j <= 0; ++j)  {
         for (i = -radius; i <= 0; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m0 += c;
             s0 += c * c;
         }
     }

     for (j = -radius; j <= 0; ++j)  {
         for (i = 0; i <= radius; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m1 += c;
             s1 += c * c;
         }
     }

     for (j = 0; j <= radius; ++j)  {
         for (i = 0; i <= radius; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m2 += c;
             s2 += c * c;
         }
     }

     for (j = 0; j <= radius; ++j)  {
         for (i = -radius; i <= 0; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m3 += c;
             s3 += c * c;
         }
     }


     float min_sigma2 = 1e+2;
     m0 /= n;
     s0 = abs(s0 / n - m0 * m0);

     float sigma2 = s0.r + s0.g + s0.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m0, 1.0);
     }

     m1 /= n;
     s1 = abs(s1 / n - m1 * m1);

     sigma2 = s1.r + s1.g + s1.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m1, 1.0);
     }

     m2 /= n;
     s2 = abs(s2 / n - m2 * m2);

     sigma2 = s2.r + s2.g + s2.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m2, 1.0);
     }

     m3 /= n;
     s3 = abs(s3 / n - m3 * m3);

     sigma2 = s3.r + s3.g + s3.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m3, 1.0);
     }
 }
);
#else
NSString *const kGPUImageKuwaharaFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;
 uniform sampler2D inputImageTexture;
 uniform int radius;

 const vec2 src_size = vec2 (1.0 / 768.0, 1.0 / 1024.0);

 void main (void)
 {
     vec2 uv = textureCoordinate;
     float n = float((radius + 1) * (radius + 1));
     int i; int j;
     vec3 m0 = vec3(0.0); vec3 m1 = vec3(0.0); vec3 m2 = vec3(0.0); vec3 m3 = vec3(0.0);
     vec3 s0 = vec3(0.0); vec3 s1 = vec3(0.0); vec3 s2 = vec3(0.0); vec3 s3 = vec3(0.0);
     vec3 c;

     for (j = -radius; j <= 0; ++j)  {
         for (i = -radius; i <= 0; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m0 += c;
             s0 += c * c;
         }
     }

     for (j = -radius; j <= 0; ++j)  {
         for (i = 0; i <= radius; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m1 += c;
             s1 += c * c;
         }
     }

     for (j = 0; j <= radius; ++j)  {
         for (i = 0; i <= radius; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m2 += c;
             s2 += c * c;
         }
     }

     for (j = 0; j <= radius; ++j)  {
         for (i = -radius; i <= 0; ++i)  {
             c = texture2D(inputImageTexture, uv + vec2(i,j) * src_size).rgb;
             m3 += c;
             s3 += c * c;
         }
     }


     float min_sigma2 = 1e+2;
     m0 /= n;
     s0 = abs(s0 / n - m0 * m0);

     float sigma2 = s0.r + s0.g + s0.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m0, 1.0);
     }

     m1 /= n;
     s1 = abs(s1 / n - m1 * m1);

     sigma2 = s1.r + s1.g + s1.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m1, 1.0);
     }

     m2 /= n;
     s2 = abs(s2 / n - m2 * m2);

     sigma2 = s2.r + s2.g + s2.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m2, 1.0);
     }

     m3 /= n;
     s3 = abs(s3 / n - m3 * m3);

     sigma2 = s3.r + s3.g + s3.b;
     if (sigma2 < min_sigma2) {
         min_sigma2 = sigma2;
         gl_FragColor = vec4(m3, 1.0);
     }
 }
);
#endif

二.效果演示

使用 GPUImageKuwaharaFilter** ** 用来图像卡通效果（黑色粗线描边），原图：

**GPUImageKuwaharaFilter** 用来图像卡通效果（黑色粗线描边），效果图：

三.源码下载

OpenGL ES Demo 下载地址 : IOS – OpenGL ES 桑原滤波/水粉画模糊效果 GPUImageKuwaharaFilter

四.猜你喜欢

1. IOS – OPenGL ES 设置图像亮度 GPUImageBrightnessFilter
2. IOS – OPenGL ES 调节图像曝光度 GPUImageExposureFilter
3. IOS – OpenGL ES 调节图像对比度 GPUImageContrastFilter
4. IOS – OPenGL ES 调节图像饱和度 GPUImageSaturationFilter
5. IOS – OPenGL ES 调节图像伽马线 GPUImageGammaFilter
6. IOS – OpenGL ES 调节图像反色 GPUImageColorInvertFilter
7. IOS – OpenGL ES 调节图像褐色 GPUImageSepiaFilter
8. IOS – OpenGL ES 调节图像灰色 GPUImageGrayscaleFilter
9. IOS – OpenGL ES 调节图像 RGB 通道 GPUImageRGBFilter
10. IOS – OpenGL ES 调节图像不透明度 GPUImageOpacityFilter
11. IOS – OpenGL ES 调节图像阴影 GPUImageHighlightShadowFilter
12. IOS – OpenGL ES 调节图像色彩替换 GPUImageFalseColorFilter
13. GPUImage – 色彩直方图 GPUImageHistogramFilter
14. GPUImage – 色彩直方图 GPUImageHistogramGenerator
15. GPUImage – 像素平均色值 GPUImageAverageColor
16. GPUImage – 亮度平均 GPUImageLuminosity
17. IOS – OpenGL ES 调节图像色度 GPUImageHueFilter
18. IOS – OpenGL ES 指定颜色抠图 GPUImageChromaKeyFilter
19. IOS – OpenGL ES 调节图像白平衡/色温 GPUImageWhiteBalanceFilter
20. IOS – OpenGL ES 设置图像 lookup 滤镜 GPUImageLookupFilter
21. IOS – OpenGL ES 设置图像滤镜 GPUImageAmatorkaFilter
22. IOS – OpenGL ES 设置图像滤镜 GPUImageSoftEleganceFilter
23. IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter
24. IOS – OpenGL ES 绘制十字 GPUImageCrosshairGenerator
25. IOS – OpenGL ES 绘制线条 GPUImageLineGenerator
26. IOS – OpenGL ES 设置图像黑白燥点 GPUImageLocalBinaryPatternFilter
27. IOS – OpenGL ES 设置图像卡通效果（黑色粗线描边） GPUImageToonFilter
28. IOS – OpenGL ES 桑原滤波/水粉画模糊效果 GPUImageKuwaharaFilter

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