图像处理之老照片特效

PS中有一种滤镜可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。它的基本处理算法以下：

1. 首先对图像从新计算RGB值，计算公式以下：

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以下：

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

混合颜色的代码以下：

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

效果以下：

滤镜彻底源代码：

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<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"; 	}  }