PS中有一种滤镜可以让图像看上去好像历经岁月，微微泛黄

英文中这种图像特效被称为Sepia Tone Effect 直译过来的意思

就是黄褐色特效。它的基本处理算法如下：

1. 首先对图像重新计算RGB值，计算公式如下：

int fr= (int)(((double)tr * 0.393) + ((double)tg * 0.769) + ((double)tb * 0.189)); int fg = (int)(((double)tr * 0.349) + ((double)tg * 0.686) + ((double)tb * 0.168)); int fb= (int)(((double)tr * 0.272) + ((double)tg * 0.534) + ((double)tb * 0.131));2. 对图像计算出来的新的RGB值根据随机权重与旧值混合。

计算随机权重的代码如下：

private double noise() { return Math.random()*0.5 + 0.5; }混合颜色的代码如下：

private double colorBlend(double scale, double dest, double src) { return (scale * dest + (1.0 - scale) * src); }效果如下：

滤镜完全源代码：

package com.gloomyfish.filter.study; import java.awt.image.BufferedImage; public class SepiaToneFilter extends AbstractBufferedImageOp { @Override public BufferedImage filter(BufferedImage src, BufferedImage dest) { int width = src.getWidth(); int height = src.getHeight(); if ( dest == null ) dest = createCompatibleDestImage( src, null ); int[] inPixels = new int[width*height]; int[] outPixels = new int[width*height]; getRGB( src, 0, 0, width, height, inPixels ); int index = 0; for(int row=0; row> 24) & 0xff; tr = (inPixels[index] >> 16) & 0xff; tg = (inPixels[index] >> 8) & 0xff; tb = inPixels[index] & 0xff; //int fr= (int)(((double)tr * 0.393) + ((double)tg * 0.769) + ((double)tb * 0.189)); //int fg = (int)(((double)tr * 0.349) + ((double)tg * 0.686) + ((double)tb * 0.168)); //int fb= (int)(((double)tr * 0.272) + ((double)tg * 0.534) + ((double)tb * 0.131)); int fr = (int)colorBlend(noise(), (tr * 0.393) + (tg * 0.769) + (tb * 0.189), tr); int fg = (int)colorBlend(noise(), (tr * 0.349) + (tg * 0.686) + (tb * 0.168), tg); int fb = (int)colorBlend(noise(), (tr * 0.272) + (tg * 0.534) + (tb * 0.131), tb); outPixels[index] = (ta << 24) | (clamp(fr) << 16) | (clamp(fg) << 8) | clamp(fb); } } setRGB( dest, 0, 0, width, height, outPixels ); return dest; } private double noise() { return Math.random()*0.5 + 0.5; } private double colorBlend(double scale, double dest, double src) { return (scale * dest + (1.0 - scale) * src); } public static int clamp(int c) { return c > 255 ? 255 :( (c < 0) ? 0: c); } public String toString() { return "Sepia Tone Effect - Effect from Photoshop App"; } }