Processing玩抠图

突然兴起想玩一下抠图，试着用自带的Examplevideo来改，花了一个中午做了个小样：

分别是白色为底与黑色为底的效果，代码如下：

import processing.video.*;
int numPixels;
int[] backgroundPixels;
Capture video;
PImage img;

void setup() {
  size(640, 480); 
  video = new Capture(this, width, height);
  video.start();
  numPixels = video.width * video.height;
  backgroundPixels = new int[numPixels];
  img = new PImage(video.width, video.height);//make a copy of video.
  frameRate(30);
}

void draw() {
  if (video.available()) {
    video.read();
  }
  img = video;//use img as a template
  img.loadPixels();
  for (int i = 0; i < numPixels; i++) {
    color currColor = img.pixels[i];
    color bkgdColor = backgroundPixels[i];
    int currR = (currColor >> 16) & 0xFF;
    int currG = (currColor >> 8) & 0xFF;
    int currB = currColor & 0xFF;
    int bkgdR = (bkgdColor >> 16) & 0xFF;
    int bkgdG = (bkgdColor >> 8) & 0xFF;
    int bkgdB = bkgdColor & 0xFF;
    int diffR = abs(currR - bkgdR);
    int diffG = abs(currG - bkgdG);
    int diffB = abs(currB - bkgdB);
    int td = 20;//set threshold to 20 pixcels;
    
    //check each pixel of the frame, set background pixels to white.
    if (diffR >td||diffG>td||diffB>td) {
      img.pixels[i] = color(currR, currG, currB);
    } else {
      img.pixels[i] = color(255, 255, 255);
    }
  }
  img.updatePixels();
  //use mouse to adjust the blur effect;
  fastblur(img,(int)map(mouseX,0,width,1,20));
  //display image.
  image(img, 0, 0);
}

void keyPressed() {
  if (key == ' ') {
    arraycopy(img.pixels, backgroundPixels);
  }
} 

void fastblur(PImage img,int radius){

  if (radius<1){
    return;
  }
  int w=img.width;
  int h=img.height;
  int wm=w-1;
  int hm=h-1;
  int wh=w*h;
  int div=radius+radius+1;
  int r[]=new int[wh];
  int g[]=new int[wh];
  int b[]=new int[wh];
  int rsum,gsum,bsum,x,y,i,p,p1,p2,yp,yi,yw;
  int vmin[] = new int[max(w,h)];
  int vmax[] = new int[max(w,h)];
  int[] pix=img.pixels;
  int dv[]=new int[256*div];
  for (i=0;i<256*div;i++){
     dv[i]=(i/div); 
  }
  
  yw=yi=0;
 
  for (y=0;y<h;y++){
    rsum=gsum=bsum=0;
    for(i=-radius;i<=radius;i++){
      p=pix[yi+min(wm,max(i,0))];
      rsum+=(p & 0xff0000)>>16;
      gsum+=(p & 0x00ff00)>>8;
      bsum+= p & 0x0000ff;
   }
    for (x=0;x<w;x++){
    
      r[yi]=dv[rsum];
      g[yi]=dv[gsum];
      b[yi]=dv[bsum];

      if(y==0){
        vmin[x]=min(x+radius+1,wm);
        vmax[x]=max(x-radius,0);
       } 
       p1=pix[yw+vmin[x]];
       p2=pix[yw+vmax[x]];

      rsum+=((p1 & 0xff0000)-(p2 & 0xff0000))>>16;
      gsum+=((p1 & 0x00ff00)-(p2 & 0x00ff00))>>8;
      bsum+= (p1 & 0x0000ff)-(p2 & 0x0000ff);
      yi++;
    }
    yw+=w;
  }
  
  for (x=0;x<w;x++){
    rsum=gsum=bsum=0;
    yp=-radius*w;
    for(i=-radius;i<=radius;i++){
      yi=max(0,yp)+x;
      rsum+=r[yi];
      gsum+=g[yi];
      bsum+=b[yi];
      yp+=w;
    }
    yi=x;
    for (y=0;y<h;y++){
      pix[yi]=0xff000000 | (dv[rsum]<<16) | (dv[gsum]<<8) | dv[bsum];
      if(x==0){
        vmin[y]=min(y+radius+1,hm)*w;
        vmax[y]=max(y-radius,0)*w;
      } 
      p1=x+vmin[y];
      p2=x+vmax[y];

      rsum+=r[p1]-r[p2];
      gsum+=g[p1]-g[p2];
      bsum+=b[p1]-b[p2];

      yi+=w;
    }
  }
}

代码主要分为2个部分：

1. main

获取摄像头帧video，使用PImage对象img作为缓存帧，通过空格保存对比帧background，使用阀值将对比帧与缓存帧之间相同的部分存为指定颜色（例如：白色、黑色），再显示不同的部分。

2. fastblur

简单高斯模糊，本来是想进行边缘柔化的，结果发现这种方法不行，看来只有另外找了。