Initial data commit

Task/Hough-transform/Java/hough-transform.java

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+import java.awt.image.*;
+import java.io.File;
+import java.io.IOException;
+import javax.imageio.*;
+
+public class HoughTransform
+{
+  public static ArrayData houghTransform(ArrayData inputData, int thetaAxisSize, int rAxisSize, int minContrast)
+  {
+    int width = inputData.width;
+    int height = inputData.height;
+    int maxRadius = (int)Math.ceil(Math.hypot(width, height));
+    int halfRAxisSize = rAxisSize >>> 1;
+    ArrayData outputData = new ArrayData(thetaAxisSize, rAxisSize);
+    // x output ranges from 0 to pi
+    // y output ranges from -maxRadius to maxRadius
+    double[] sinTable = new double[thetaAxisSize];
+    double[] cosTable = new double[thetaAxisSize];
+    for (int theta = thetaAxisSize - 1; theta >= 0; theta--)
+    {
+      double thetaRadians = theta * Math.PI / thetaAxisSize;
+      sinTable[theta] = Math.sin(thetaRadians);
+      cosTable[theta] = Math.cos(thetaRadians);
+    }
+
+    for (int y = height - 1; y >= 0; y--)
+    {
+      for (int x = width - 1; x >= 0; x--)
+      {
+        if (inputData.contrast(x, y, minContrast))
+        {
+          for (int theta = thetaAxisSize - 1; theta >= 0; theta--)
+          {
+            double r = cosTable[theta] * x + sinTable[theta] * y;
+            int rScaled = (int)Math.round(r * halfRAxisSize / maxRadius) + halfRAxisSize;
+            outputData.accumulate(theta, rScaled, 1);
+          }
+        }
+      }
+    }
+    return outputData;
+  }
+
+  public static class ArrayData
+  {
+    public final int[] dataArray;
+    public final int width;
+    public final int height;
+
+    public ArrayData(int width, int height)
+    {
+      this(new int[width * height], width, height);
+    }
+
+    public ArrayData(int[] dataArray, int width, int height)
+    {
+      this.dataArray = dataArray;
+      this.width = width;
+      this.height = height;
+    }
+
+    public int get(int x, int y)
+    {  return dataArray[y * width + x];  }
+
+    public void set(int x, int y, int value)
+    {  dataArray[y * width + x] = value;  }
+
+    public void accumulate(int x, int y, int delta)
+    {  set(x, y, get(x, y) + delta);  }
+
+    public boolean contrast(int x, int y, int minContrast)
+    {
+      int centerValue = get(x, y);
+      for (int i = 8; i >= 0; i--)
+      {
+        if (i == 4)
+          continue;
+        int newx = x + (i % 3) - 1;
+        int newy = y + (i / 3) - 1;
+        if ((newx < 0) || (newx >= width) || (newy < 0) || (newy >= height))
+          continue;
+        if (Math.abs(get(newx, newy) - centerValue) >= minContrast)
+          return true;
+      }
+      return false;
+    }
+
+    public int getMax()
+    {
+      int max = dataArray[0];
+      for (int i = width * height - 1; i > 0; i--)
+        if (dataArray[i] > max)
+          max = dataArray[i];
+      return max;
+    }
+  }
+
+  public static ArrayData getArrayDataFromImage(String filename) throws IOException
+  {
+    BufferedImage inputImage = ImageIO.read(new File(filename));
+    int width = inputImage.getWidth();
+    int height = inputImage.getHeight();
+    int[] rgbData = inputImage.getRGB(0, 0, width, height, null, 0, width);
+    ArrayData arrayData = new ArrayData(width, height);
+    // Flip y axis when reading image
+    for (int y = 0; y < height; y++)
+    {
+      for (int x = 0; x < width; x++)
+      {
+        int rgbValue = rgbData[y * width + x];
+        rgbValue = (int)(((rgbValue & 0xFF0000) >>> 16) * 0.30 + ((rgbValue & 0xFF00) >>> 8) * 0.59 + (rgbValue & 0xFF) * 0.11);
+        arrayData.set(x, height - 1 - y, rgbValue);
+      }
+    }
+    return arrayData;
+  }
+
+  public static void writeOutputImage(String filename, ArrayData arrayData) throws IOException
+  {
+    int max = arrayData.getMax();
+    BufferedImage outputImage = new BufferedImage(arrayData.width, arrayData.height, BufferedImage.TYPE_INT_ARGB);
+    for (int y = 0; y < arrayData.height; y++)
+    {
+      for (int x = 0; x < arrayData.width; x++)
+      {
+        int n = Math.min((int)Math.round(arrayData.get(x, y) * 255.0 / max), 255);
+        outputImage.setRGB(x, arrayData.height - 1 - y, (n << 16) | (n << 8) | 0x90 | -0x01000000);
+      }
+    }
+    ImageIO.write(outputImage, "PNG", new File(filename));
+    return;
+  }
+
+  public static void main(String[] args) throws IOException
+  {
+    ArrayData inputData = getArrayDataFromImage(args[0]);
+    int minContrast = (args.length >= 4) ? 64 : Integer.parseInt(args[4]);
+    ArrayData outputData = houghTransform(inputData, Integer.parseInt(args[2]), Integer.parseInt(args[3]), minContrast);
+    writeOutputImage(args[1], outputData);
+    return;
+  }
+}