IOS – OpenGL ES 设置图像黑白噪点 GPUImageLocalBinaryPatternFilter

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猿说编程[Python和C]

发布于 2023-03-25 10:02:49

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发布于 2023-03-25 10:02:49

文章被收录于专栏：猿说编程

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 转场零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 特效零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 函数零基础 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.

GPUImageLocalBinaryPatternFilter 属于 GPUImage 图像处理相关，用来图像黑白化，并有大量噪点，shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 设置图像黑白化 ，并有大量噪点GPUImageLocalBinaryPatternFilter
//@Time:2022/04/20 07:30
//@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 kGPUImageLocalBinaryPatternFragmentShaderString = SHADER_STRING
(
 precision highp float;

 varying vec2 textureCoordinate;
 varying vec2 leftTextureCoordinate;
 varying vec2 rightTextureCoordinate;

 varying vec2 topTextureCoordinate;
 varying vec2 topLeftTextureCoordinate;
 varying vec2 topRightTextureCoordinate;

 varying vec2 bottomTextureCoordinate;
 varying vec2 bottomLeftTextureCoordinate;
 varying vec2 bottomRightTextureCoordinate;

 uniform sampler2D inputImageTexture;

 void main()
 {
     lowp float centerIntensity = texture2D(inputImageTexture, textureCoordinate).r;
     lowp float bottomLeftIntensity = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
     lowp float topRightIntensity = texture2D(inputImageTexture, topRightTextureCoordinate).r;
     lowp float topLeftIntensity = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
     lowp float bottomRightIntensity = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
     lowp float leftIntensity = texture2D(inputImageTexture, leftTextureCoordinate).r;
     lowp float rightIntensity = texture2D(inputImageTexture, rightTextureCoordinate).r;
     lowp float bottomIntensity = texture2D(inputImageTexture, bottomTextureCoordinate).r;
     lowp float topIntensity = texture2D(inputImageTexture, topTextureCoordinate).r;

     lowp float byteTally = 1.0 / 255.0 * step(centerIntensity, topRightIntensity);
     byteTally += 2.0 / 255.0 * step(centerIntensity, topIntensity);
     byteTally += 4.0 / 255.0 * step(centerIntensity, topLeftIntensity);
     byteTally += 8.0 / 255.0 * step(centerIntensity, leftIntensity);
     byteTally += 16.0 / 255.0 * step(centerIntensity, bottomLeftIntensity);
     byteTally += 32.0 / 255.0 * step(centerIntensity, bottomIntensity);
     byteTally += 64.0 / 255.0 * step(centerIntensity, bottomRightIntensity);
     byteTally += 128.0 / 255.0 * step(centerIntensity, rightIntensity);

     // TODO: Replace the above with a dot product and two vec4s
     // TODO: Apply step to a matrix, rather than individually

     gl_FragColor = vec4(byteTally, byteTally, byteTally, 1.0);
 }
);
#else
NSString *const kGPUImageLocalBinaryPatternFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;
 varying vec2 leftTextureCoordinate;
 varying vec2 rightTextureCoordinate;

 varying vec2 topTextureCoordinate;
 varying vec2 topLeftTextureCoordinate;
 varying vec2 topRightTextureCoordinate;

 varying vec2 bottomTextureCoordinate;
 varying vec2 bottomLeftTextureCoordinate;
 varying vec2 bottomRightTextureCoordinate;

 uniform sampler2D inputImageTexture;

 void main()
 {
     float centerIntensity = texture2D(inputImageTexture, textureCoordinate).r;
     float bottomLeftIntensity = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
     float topRightIntensity = texture2D(inputImageTexture, topRightTextureCoordinate).r;
     float topLeftIntensity = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
     float bottomRightIntensity = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
     float leftIntensity = texture2D(inputImageTexture, leftTextureCoordinate).r;
     float rightIntensity = texture2D(inputImageTexture, rightTextureCoordinate).r;
     float bottomIntensity = texture2D(inputImageTexture, bottomTextureCoordinate).r;
     float topIntensity = texture2D(inputImageTexture, topTextureCoordinate).r;

     float byteTally = 1.0 / 255.0 * step(centerIntensity, topRightIntensity);
     byteTally += 2.0 / 255.0 * step(centerIntensity, topIntensity);
     byteTally += 4.0 / 255.0 * step(centerIntensity, topLeftIntensity);
     byteTally += 8.0 / 255.0 * step(centerIntensity, leftIntensity);
     byteTally += 16.0 / 255.0 * step(centerIntensity, bottomLeftIntensity);
     byteTally += 32.0 / 255.0 * step(centerIntensity, bottomIntensity);
     byteTally += 64.0 / 255.0 * step(centerIntensity, bottomRightIntensity);
     byteTally += 128.0 / 255.0 * step(centerIntensity, rightIntensity);

     // TODO: Replace the above with a dot product and two vec4s
     // TODO: Apply step to a matrix, rather than individually

     gl_FragColor = vec4(byteTally, byteTally, byteTally, 1.0);
 }
);
#endif