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：

 

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<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";

	}



}