package PEU.P.image;
import java.awt.image.BufferedImage;
import java.io.IOException;
//作者,著作权人： 罗瑶光，浏阳
public class Strech {
  public int[][] P(int[][] g,double d,double e)
   throws IOException {
    int histgram[] = new int[256];
    for (int i = 0; i < g.length; i++) {
      for (int j = 0; j < g[0].length; j++) {
        ++histgram[g[i][j]];
      }
    }
    float p = 0;
    int br = 0,dr = 0;
    for(int i=0;i<256;i++) {
      p=p+histgram[i];
      if(p > d* g.length*g[0].length){
        dr=i;
        break;
      }
    }
    //System.out.println("dr:"+dr);
    p = 0;
    for(int i=0;i<256;i++){
      p=p+histgram[i];
      if(p > e* g.length*g[0].length){
        br=i;
        break;
      }
    }
    //System.out.println("br:"+br);
    int out[][] = new int[g.length][g[0].length];
    for (int i = 0; i < g.length; i++) {
      for (int j = 0; j < g[0].length; j++) {
        if(br-dr!=0) {
          out[i][j]=(g[i][j]-dr)*255/(br-dr);
        } 
      }
    }
    return  new CheckRange().P(out);   
  }

  public BufferedImage P(BufferedImage lygimage
  , double d, double e) throws IOException {
    //image to r[][] g[][] b[][]
    //r[][]
    //g[][]
    //b[][]
    //r[][]g[][]b[][] to image
    //image to r[][] g[][] b[][]
    int r[][]=new ReadWritePng().REDpngRead(lygimage);
    int g[][]=new ReadWritePng().GRNpngRead(lygimage);
    int b[][]=new ReadWritePng().BLUpngRead(lygimage);
    //r[][]
    r=P(r,d,e); 
    //g[][]
    g=P(g,d,e); 
    //b[][]
    b=P(b,d,e); 
    //r[][]g[][]b[][] to image
    lygimage=new ReadWritePng().createBufferImage(r,g,b);
    return lygimage;
  }
}