java图像处理之倒角距离变换

package com.gloomyfish.image.transform;  import java.awt.Color; import java.awt.image.BufferedImage; import java.util.Arrays;  import com.gloomyfish.filter.study.AbstractBufferedImageOp;  public class CDTFilter extends AbstractBufferedImageOp {   private float[] dis; // nn-distances   private int[] pos; // nn-positions, 32 bit index   private Color bakcgroundColor;      public CDTFilter(Color bgColor)   {     this.bakcgroundColor = bgColor;   }    @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];     pos = new int[width * height];     dis = new float[width * height];     src.getRGB(0, 0, width, height, inPixels, 0, width);     // 随机生成距离变换点     int index = 0;     Arrays.fill(dis, Float.MAX_VALUE);     int numOfFC = 0;     for (int row = 0; row < height; row++) {       for (int col = 0; col < width; col++) {         index = row * width + col;         if (inPixels[index] != bakcgroundColor.getRGB()) {           dis[index] = 0;           pos[index] = index;           numOfFC++;         }       }     }     final float d1 = 1;     final float d2 = (float) Math.sqrt(d1 * d1 + d1 * d1);     System.out.println(numOfFC);     float nd, nd_tmp;     int i, in, cols, rows, nearestPixel;      // 1 2 3     // 0 i 4     // 7 6 5     // first pass: forward -> L->R, T-B     for (rows = 1; rows < height - 1; rows++) {       for (cols = 1; cols < width - 1; cols++) {         i = rows * width + cols;          nd = dis[i];         nearestPixel = pos[i];         if (nd != 0) { // skip background pixels           in = i;            in += -1; // 0           if ((nd_tmp = d1 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            in += -width; // 1           if ((nd_tmp = d2 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            in += +1; // 2           if ((nd_tmp = d1 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            in += +1; // 3           if ((nd_tmp = d2 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            dis[i] = nd;           pos[i] = nearestPixel;         }       }     }      // second pass: backwards -> R->L, B-T     // exactly same as first pass, just in the reverse direction     for (rows = height - 2; rows >= 1; rows--) {       for (cols = width - 2; cols >= 1; cols--) {         i = rows * width + cols;          nd = dis[i];         nearestPixel = pos[i];         if (nd != 0) {           in = i;            in += +1; // 4           if ((nd_tmp = d1 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            in += +width; // 5           if ((nd_tmp = d2 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            in += -1; // 6           if ((nd_tmp = d1 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            in += -1; // 7           if ((nd_tmp = d2 + dis[in]) < nd) {             nd = nd_tmp;             nearestPixel = pos[in];           }            dis[i] = nd;           pos[i] = nearestPixel;          }       }     }      for (int row = 0; row < height; row++) {       for (int col = 0; col < width; col++) {         index = row * width + col;         if (Float.MAX_VALUE != dis[index]) {           int gray = clamp((int) (dis[index]));           inPixels[index] = (255 << 24) | (gray << 16) | (gray << 8)               | gray;         }       }     }     setRGB(dest, 0, 0, width, height, inPixels);     return dest;   }    private int clamp(int i) {     return i > 255 ? 255 : (i < 0 ? 0 : i);   }  }