package Algorithms;
import java.util.Arrays;
public class Zha84{ static final byte[] lut = stringToLut( "00010013003110130000000020203033" + "00000000300000000000000020003022" + "00000000000000000000000000000000" + "20000000200020003000000030003020" + "00310013000000010000000000000001" + "31000000000000002000000000000000" + "23130013000000010000000000000000" + "23010001000000003301000022002000" );
static byte[] stringToLut(String str) { byte[] out = new byte[256]; for (int i = 0; i < out.length; i++) out[i] = (byte)(str.charAt(i) - '0'); return out; }
public static void skeletonize( byte[] outSkeletonImage, byte[] scratchSkeletonImage, byte[] inputImage, int width, int height, int maxSkelIterations ) { Arrays.fill(outSkeletonImage, 0, width, (byte)0); Arrays.fill(scratchSkeletonImage, 0, width, (byte)0);
for (int i = 1; i < height - 1; i++) { outSkeletonImage[i*width] = 0; scratchSkeletonImage[i*width] = 0; for (int j = 1; j < width - 1; j++) { int idx = j + width*i; outSkeletonImage[idx] = (byte)(inputImage[idx] >>> 31); } outSkeletonImage[(i+1)*width-1] = 0; scratchSkeletonImage[(i+1)*width-1] = 0; }
int lastRow = (height-1) * width; Arrays.fill(outSkeletonImage, lastRow, lastRow + width, (byte)0); Arrays.fill(scratchSkeletonImage, lastRow, lastRow + width, (byte)0);
byte[] a = null, b = null;
int nRemovals; int step = 0; do { nRemovals = 0; a = outSkeletonImage; b = scratchSkeletonImage;
for (int pass = 1; pass <= 2; pass++) { for (int i = 1; i < height-1; i++) { for (int j = 1; j < width-1; j++) { int idx = j + width*i; int shouldKeep = 1;
if (a[idx] != 0) { int value = lut[ a[idx-width-1] | a[idx-width] << 1 | a[idx-width+1] << 2 | a[idx+1] << 3 | a[idx+width+1] << 4 | a[idx+width] << 5 | a[idx+width-1] << 6 | a[idx-1] << 7 ];
//boolean shouldKeep = value != 3 && value != pass; shouldKeep = ((value-3) >>> 31 | -(value-3) >>> 31) & ((value-pass) >>> 31 | -(value-pass) >>> 31); }
b[idx] = (byte)(shouldKeep * a[idx]); nRemovals += shouldKeep ^ 1; } }
byte[] temp = a; a = b; b = temp; } //System.out.println("nRemovals: " + nRemovals); } while (nRemovals != 0 && (maxSkelIterations <= 0 || ++step < maxSkelIterations)); }}
