图像处理之老照片特效

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：

[java]
nt 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)(((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：

[java]
private double noise() {
return Math.random()*0.5 + 0.5;
}

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

[java]
private double colorBlend(double scale, double dest, double src) {
return (scale * dest + (1.0 - scale) * src);
}

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：

[java]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 int ta = 0, tr = 0, tg = 0, tb = 0;
for(int col=0; 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";
}

}