介紹幾種常見的將兩張影象混合在一起形成一張新的影象的演算法，

首先看一下下面演算法演示中要使用的兩張影象：

為了得到更好的混合效果，我選擇了兩張一樣大小的圖片。

方法一：

通過簡單對於畫素點的畫素相乘得到輸出畫素值，程式碼演示如下：

private int modeOne(int v1, int v2) {
return (v1 * v2) / 255;
}

方法一的效果如下：

通過計算兩個畫素之和再減去方法一的輸出值，程式碼如下：

private int modeTwo(int v1, int v2) {
	return v1 + v2 - v1 * v2 / 255;
}

方法二的效果如下：

通過畫素值128這個特殊的中值來求取輸出值，程式碼如下：

private int modeThree(int v1, int v2) {
	return (v2 < 128) ? (2 * v1 * v2 / 255):(255 - 2 * (255 - v1) * (255 - v2) / 255);
}

方法三的效果如下：

方法四：

與方法三不同，中值127.5被用在計算等式中，程式碼如下：

private int modeFour(double v1, double v2) {
  if ( v1 > 127.5 ){
      return (int)(v2 + (255.0 - v2) * ((v1 - 127.5) / 127.5) * (0.5 - Math.abs(v2-127.5)/255.0));
   }else{
      return (int)(v2 - v2 * ((127.5 -  v1) / 127.5) * (0.5 - Math.abs(v2-127.5)/255.0));
   }
}
 

方法四的效果如下：

中值計算考慮，是方法一的升級版本，使得混合更加精細,程式碼如下：

private int modeFive(double v1, double v2) {
  if ( v1 > 127.5 ){
      return (int)(v2 + (255.0 - v2) * ((v1 - 127.5) / 127.5));
   }else{
      return (int)(v2 * v1 / 127.5);
   }
}

方法五的效果如下：

package com.gloomyfish.filter.study;

import java.awt.image.BufferedImage;
/***
 * i get these blend method from html5 demo then i decide to 
 * translate these java script methods into java
 * 偶爾我也會寫中文註釋, 常見的影象混合方法
 * @author fish
 * @date 2012-11-28
 */
public class ImageBlendFilter extends AbstractBufferedImageOp {
	/** Define the blend mode */
	public final static int MULTIPLY_PIXEL = 1;
	public final static int SCREEN_PIXEL = 2;
	public final static int OVERLAY_PIXEL = 3;
	public final static int SOFTLIGHT_PIXEL = 4;
	public final static int HARDLIGHT_PIXEL = 5;
	
	private int mode;
	private BufferedImage secondImage;
	public ImageBlendFilter() {
		mode = 1;
	}

	public void setBlendMode(int mode) {
		this.mode = mode;
	}
	
	public void setSecondImage(BufferedImage image) {
		this.secondImage = image;
	}
	

	@Override
	public BufferedImage filter(BufferedImage src, BufferedImage dest) {
		checkImages(src);
		int width = src.getWidth();
        int height = src.getHeight();

        if ( dest == null )
        	dest = createCompatibleDestImage( src, null );

        int[] input1 = new int[width*height];
        int[] input2 = new int[secondImage.getWidth() * secondImage.getHeight()];
        int[] outPixels = new int[width*height];
        getRGB( src, 0, 0, width, height, input1);
        getRGB( secondImage, 0, 0, secondImage.getWidth(), secondImage.getHeight(), input2);
        int index = 0;
        int ta1 = 0, tr1 = 0, tg1 = 0, tb1 = 0;
        for(int row=0; row<height; row++) {
        	for(int col=0; col<width; col++) {
        		index = row * width + col;
        		ta1 = (input1[index] >> 24) & 0xff;
                tr1 = (input1[index] >> 16) & 0xff;
                tg1 = (input1[index] >> 8) & 0xff;
                tb1 = input1[index] & 0xff;
                int[] rgb = getBlendData(tr1, tg1, tb1, input2, row, col);
                outPixels[index] = (ta1 << 24) | (rgb[0] << 16) | (rgb[1] << 8) | rgb[2];
                
        	}
        }
        setRGB( dest, 0, 0, width, height, outPixels );
        return dest;
	}

	private int[] getBlendData(int tr1, int tg1, int tb1, int[] input,int row, int col) {
		int width = secondImage.getWidth();
        int height = secondImage.getHeight();
        if(col >= width || row >= height) {
        	return new int[]{tr1, tg1, tb1};
        }
        int index = row * width + col;
		// int ta = (input[index] >> 24) & 0xff;
        int tr = (input[index] >> 16) & 0xff;
        int tg = (input[index] >> 8) & 0xff;
        int tb = input[index] & 0xff;
        int[] rgb = new int[3];
        if(mode == 1) {
        	rgb[0] = modeOne(tr1, tr);
        	rgb[1] = modeOne(tg1, tg);
        	rgb[2] = modeOne(tb1, tb);
        }
        else if(mode == 2) {
        	rgb[0] = modeTwo(tr1, tr);
        	rgb[1] = modeTwo(tg1, tg);
        	rgb[2] = modeTwo(tb1, tb);        	
        }
        else if(mode == 3) {
        	rgb[0] = modeThree(tr1, tr);
        	rgb[1] = modeThree(tg1, tg);
        	rgb[2] = modeThree(tb1, tb);        	
        }
        else if(mode == 4) {
        	rgb[0] = modeFour(tr1, tr);
        	rgb[1] = modeFour(tg1, tg);
        	rgb[2] = modeFour(tb1, tb);        	
        }
        else if(mode == 5) {
        	rgb[0] = modeFive(tr1, tr);
        	rgb[1] = modeFive(tg1, tg);
        	rgb[2] = modeFive(tb1, tb);        	
        }
        return rgb;
	}
	
	private int modeOne(int v1, int v2) {
		return (v1 * v2) / 255;
	}
	
	private int modeTwo(int v1, int v2) {
		return v1 + v2 - v1 * v2 / 255;
	}
	
	private int modeThree(int v1, int v2) {
		return (v2 < 128) ? (2 * v1 * v2 / 255):(255 - 2 * (255 - v1) * (255 - v2) / 255);
	}
	
	private int modeFour(double v1, double v2) {
      if ( v1 > 127.5 ){
          return (int)(v2 + (255.0 - v2) * ((v1 - 127.5) / 127.5) * (0.5 - Math.abs(v2-127.5)/255.0));
       }else{
          return (int)(v2 - v2 * ((127.5 -  v1) / 127.5) * (0.5 - Math.abs(v2-127.5)/255.0));
       }
	}
	
	private int modeFive(double v1, double v2) {
      if ( v1 > 127.5 ){
          return (int)(v2 + (255.0 - v2) * ((v1 - 127.5) / 127.5));
       }else{
          return (int)(v2 * v1 / 127.5);
       }
	}

	private void checkImages(BufferedImage src) {
		int width = src.getWidth();
        int height = src.getHeight();
		if(secondImage == null || secondImage.getWidth() > width || secondImage.getHeight() > height) {
			throw new IllegalArgumentException("the width, height of the input image must be great than blend image");
		}
	}

}
 

如果覺得效果很有趣，請頂一下，謝謝！