IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter

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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.

GPUImageSharpenFilter 属于 GPUImage 图像处理相关,用来处理图像锐化效果,shader 源码如下:

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter
//@Time:2022/04/17 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!
/******************************************************************************************/


NSString *const kGPUImageSharpenVertexShaderString = SHADER_STRING
(
 attribute vec4 position;
 attribute vec4 inputTextureCoordinate;
 
 uniform float imageWidthFactor; 
 uniform float imageHeightFactor; 
 uniform float sharpness;
 
 varying vec2 textureCoordinate;
 varying vec2 leftTextureCoordinate;
 varying vec2 rightTextureCoordinate; 
 varying vec2 topTextureCoordinate;
 varying vec2 bottomTextureCoordinate;
 
 varying float centerMultiplier;
 varying float edgeMultiplier;
 
 void main()
 {
     gl_Position = position;
     
     vec2 widthStep = vec2(imageWidthFactor, 0.0);
     vec2 heightStep = vec2(0.0, imageHeightFactor);
     
     textureCoordinate = inputTextureCoordinate.xy;
     leftTextureCoordinate = inputTextureCoordinate.xy - widthStep;
     rightTextureCoordinate = inputTextureCoordinate.xy + widthStep;
     topTextureCoordinate = inputTextureCoordinate.xy + heightStep;     
     bottomTextureCoordinate = inputTextureCoordinate.xy - heightStep;
     
     centerMultiplier = 1.0 + 4.0 * sharpness;
     edgeMultiplier = sharpness;
 }
);


#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImageSharpenFragmentShaderString = SHADER_STRING
(
 precision highp float;
 
 varying highp vec2 textureCoordinate;
 varying highp vec2 leftTextureCoordinate;
 varying highp vec2 rightTextureCoordinate; 
 varying highp vec2 topTextureCoordinate;
 varying highp vec2 bottomTextureCoordinate;
 
 varying highp float centerMultiplier;
 varying highp float edgeMultiplier;

 uniform sampler2D inputImageTexture;
 
 void main()
 {
     mediump vec3 textureColor = texture2D(inputImageTexture, textureCoordinate).rgb;
     mediump vec3 leftTextureColor = texture2D(inputImageTexture, leftTextureCoordinate).rgb;
     mediump vec3 rightTextureColor = texture2D(inputImageTexture, rightTextureCoordinate).rgb;
     mediump vec3 topTextureColor = texture2D(inputImageTexture, topTextureCoordinate).rgb;
     mediump vec3 bottomTextureColor = texture2D(inputImageTexture, bottomTextureCoordinate).rgb;

     gl_FragColor = vec4((textureColor * centerMultiplier - (leftTextureColor * edgeMultiplier + rightTextureColor * edgeMultiplier + topTextureColor * edgeMultiplier + bottomTextureColor * edgeMultiplier)), texture2D(inputImageTexture, bottomTextureCoordinate).w);
 }
);
#else
NSString *const kGPUImageSharpenFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;
 varying vec2 leftTextureCoordinate;
 varying vec2 rightTextureCoordinate;
 varying vec2 topTextureCoordinate;
 varying vec2 bottomTextureCoordinate;
 
 varying float centerMultiplier;
 varying float edgeMultiplier;
 
 uniform sampler2D inputImageTexture;
 
 void main()
 {
     vec3 textureColor = texture2D(inputImageTexture, textureCoordinate).rgb;
     vec3 leftTextureColor = texture2D(inputImageTexture, leftTextureCoordinate).rgb;
     vec3 rightTextureColor = texture2D(inputImageTexture, rightTextureCoordinate).rgb;
     vec3 topTextureColor = texture2D(inputImageTexture, topTextureCoordinate).rgb;
     vec3 bottomTextureColor = texture2D(inputImageTexture, bottomTextureCoordinate).rgb;
     
     gl_FragColor = vec4((textureColor * centerMultiplier - (leftTextureColor * edgeMultiplier + rightTextureColor * edgeMultiplier + topTextureColor * edgeMultiplier + bottomTextureColor * edgeMultiplier)), texture2D(inputImageTexture, bottomTextureCoordinate).w);
 }
);
#endif

二.效果演示

使用GPUImageSharpenFilter 处理图片示例,原图:

IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter

GPUImageSharpenFilter 效果图:

IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter

三.源码下载

OpenGL ES Demo 下载地址 : IOS – OpenGL ES 设置图像滤镜 GPUImageSharpenFilter

IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter

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 设置图像滤镜 GPUImageLineGenerator
  24. IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter

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