目录
- 一.简介
- 二.效果演示
- 三.源码下载
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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.
GPUImageKuwaharaFilter GPUImage 图像桑原滤波/水粉画模糊效果，shader 源码如下：
代码语言：javascript复制/******************************************************************************************/
//@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
