图像处理之老照片特效

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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 {@Overridepublic 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<height; row++) {        int ta = 0, tr = 0, tg = 0, tb = 0;        for(int col=0; col<width; col++) {        index = row * width + col;        ta = (inPixels[index] >> 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";}}