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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
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.
GPUImageNonMaximumSuppressionFilter 属于 GPUImage 图像视觉效果相关，用来处理**图像图像显示亮度最高的像素,其他为黑效果**。shader 源码如下：
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/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES GPUImage 图像显示亮度最高的像素,其他为黑 GPUImageNonMaximumSuppressionFilter
//@Time:2022/06/21 06:30
//@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 kGPUImageNonMaximumSuppressionFragmentShaderString = SHADER_STRING
(
uniform sampler2D inputImageTexture;
varying highp vec2 textureCoordinate;
varying highp vec2 leftTextureCoordinate;
varying highp vec2 rightTextureCoordinate;
varying highp vec2 topTextureCoordinate;
varying highp vec2 topLeftTextureCoordinate;
varying highp vec2 topRightTextureCoordinate;
varying highp vec2 bottomTextureCoordinate;
varying highp vec2 bottomLeftTextureCoordinate;
varying highp vec2 bottomRightTextureCoordinate;
void main()
{
lowp float bottomColor = texture2D(inputImageTexture, bottomTextureCoordinate).r;
lowp float bottomLeftColor = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
lowp float bottomRightColor = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
lowp vec4 centerColor = texture2D(inputImageTexture, textureCoordinate);
lowp float leftColor = texture2D(inputImageTexture, leftTextureCoordinate).r;
lowp float rightColor = texture2D(inputImageTexture, rightTextureCoordinate).r;
lowp float topColor = texture2D(inputImageTexture, topTextureCoordinate).r;
lowp float topRightColor = texture2D(inputImageTexture, topRightTextureCoordinate).r;
lowp float topLeftColor = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
// Use a tiebreaker for pixels to the left and immediately above this one
lowp float multiplier = 1.0 - step(centerColor.r, topColor);
multiplier = multiplier * (1.0 - step(centerColor.r, topLeftColor));
multiplier = multiplier * (1.0 - step(centerColor.r, leftColor));
multiplier = multiplier * (1.0 - step(centerColor.r, bottomLeftColor));
lowp float maxValue = max(centerColor.r, bottomColor);
maxValue = max(maxValue, bottomRightColor);
maxValue = max(maxValue, rightColor);
maxValue = max(maxValue, topRightColor);
gl_FragColor = vec4((centerColor.rgb * step(maxValue, centerColor.r) * multiplier), 1.0);
}
);
#else
NSString *const kGPUImageNonMaximumSuppressionFragmentShaderString = SHADER_STRING
(
uniform sampler2D inputImageTexture;
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;
void main()
{
float bottomColor = texture2D(inputImageTexture, bottomTextureCoordinate).r;
float bottomLeftColor = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
float bottomRightColor = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
vec4 centerColor = texture2D(inputImageTexture, textureCoordinate);
float leftColor = texture2D(inputImageTexture, leftTextureCoordinate).r;
float rightColor = texture2D(inputImageTexture, rightTextureCoordinate).r;
float topColor = texture2D(inputImageTexture, topTextureCoordinate).r;
float topRightColor = texture2D(inputImageTexture, topRightTextureCoordinate).r;
float topLeftColor = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
// Use a tiebreaker for pixels to the left and immediately above this one
float multiplier = 1.0 - step(centerColor.r, topColor);
multiplier = multiplier * (1.0 - step(centerColor.r, topLeftColor));
multiplier = multiplier * (1.0 - step(centerColor.r, leftColor));
multiplier = multiplier * (1.0 - step(centerColor.r, bottomLeftColor));
float maxValue = max(centerColor.r, bottomColor);
maxValue = max(maxValue, bottomRightColor);
maxValue = max(maxValue, rightColor);
maxValue = max(maxValue, topRightColor);
gl_FragColor = vec4((centerColor.rgb * step(maxValue, centerColor.r) * multiplier), 1.0);
}
);
#endif
使用 GPUImageNonMaximumSuppressionFilter 完成图像显示亮度最高的像素,其他为黑****,原图如下：
使用 GPUImageNonMaximumSuppressionFilter 完成图像显示亮度最高的像素,其他为黑****,效果如下：
OpenGL ES Demo 下载地址 : IOS OpenGL ES GPUImage 图像显示亮度最高的像素,其他为黑 GPUImageNonMaximumSuppressionFilter
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