Initial refactorings to support multiple kinds of black point estimation

git-svn-id: https://zxing.googlecode.com/svn/trunk@50 59b500cc-1b3d-0410-9834-0bbf25fbcc57

core/src/com/google/zxing/BlackPointEstimationMethod.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2007 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.zxing;
+
+/**
+ * <p>Enumerates different methods of sampling an imagine to estimate a black point.</p>
+ * 
+ * @author srowen@google.com (Sean Owen), dswitkin@google.com (Daniel Switkin)
+ */
+public final class BlackPointEstimationMethod {
+
+  /** Method probably most suitable for use with 2D barcdoe format. */
+  public static final BlackPointEstimationMethod TWO_D_SAMPLING = new BlackPointEstimationMethod();
+  /** Method probably most suitable for 1D barcode decoding, where one row at a time is sampled. */
+  public static final BlackPointEstimationMethod ROW_SAMPLING = new BlackPointEstimationMethod();
+
+  private BlackPointEstimationMethod() {
+    // do nothing
+  }
+
+}

core/src/com/google/zxing/MonochromeBitmapSource.java

@@ -19,8 +19,8 @@ package com.google.zxing;
 import com.google.zxing.common.BitArray;
 
 /**
- * Encapsulates a generic black-and-white bitmap -- a collection of pixels in two dimensions.
- * This unifies many possible representations, like AWT's <code>BufferedImage</code>.
+ * <p>Encapsulates a generic black-and-white bitmap -- a collection of pixels in two dimensions.
+ * This unifies many possible representations, like AWT's <code>BufferedImage</code>.</p>
  *
  * @author srowen@google.com (Sean Owen)
  */
@@ -34,9 +34,9 @@ public interface MonochromeBitmapSource {
   boolean isBlack(int x, int y);
 
   /**
-   * Returns an entire row of black/white pixels as an array of bits, where "true" means "black".
+   * <p>Returns an entire row of black/white pixels as an array of bits, where "true" means "black".
    * This is a sort of "bulk get" operation intended to enable efficient access in
-   * certain situations.
+   * certain situations.</p>
    *
    * @param y vertical offset, from top, of the row of pixels
    * @param row if not null, {@link BitArray} to write pixels into. If null, a new {@link BitArray}
@@ -58,4 +58,22 @@ public interface MonochromeBitmapSource {
    */
   int getWidth();
 
+  /**
+   * <p>Estimates black point according to the given method, which is optionally parameterized by
+   * a single int argument. For {@link BlackPointEstimationMethod#ROW_SAMPLING}, this
+   * specifies the row to sample.</p>
+   *
+   * <p>The estimated value will be used in subsequent computations that rely on an estimated black
+   * point.</p>
+   *
+   * @param method black point estimation method
+   * @param argument method-specific argument
+   */
+  void estimateBlackPoint(BlackPointEstimationMethod method, int argument);
+
+  /**
+   * @return {@link BlackPointEstimationMethod} representing last sampling method used
+   */
+  BlackPointEstimationMethod getLastEstimationMethod();
+
 }

core/src/com/google/zxing/qrcode/detector/Detector.java

@@ -16,6 +16,7 @@
 
 package com.google.zxing.qrcode.detector;
 
+import com.google.zxing.BlackPointEstimationMethod;
 import com.google.zxing.MonochromeBitmapSource;
 import com.google.zxing.ReaderException;
 import com.google.zxing.ResultPoint;
@@ -45,6 +46,9 @@ public final class Detector {
   public DetectorResult detect() throws ReaderException {
 
     MonochromeBitmapSource image = this.image;
+    if (!BlackPointEstimationMethod.TWO_D_SAMPLING.equals(image.getLastEstimationMethod())) {
+      image.estimateBlackPoint(BlackPointEstimationMethod.TWO_D_SAMPLING, 0);
+    }
 
     FinderPatternFinder finder = new FinderPatternFinder(image);
     FinderPatternInfo info = finder.find();
@@ -93,27 +97,6 @@ public final class Detector {
     GridSampler sampler = GridSampler.getInstance();
     BitMatrix bits = sampler.sampleGrid(image, topLeft, topRight, bottomLeft, alignmentPattern, dimension);
 
-    /*
-    try {
-      BufferedImage outImage =
-          new BufferedImage(dimension,
-                            dimension,
-                            BufferedImage.TYPE_BYTE_BINARY);
-      for (int i = 0; i < dimension; i++) {
-        for (int j = 0; j < dimension; j++) {
-          if (bits.get(i, j)) {
-            outImage.setRGB(j, i, 0xFF000000);
-          } else {
-            outImage.setRGB(j, i, 0xFFFFFFFF);
-          }
-        }
-      }
-      ImageIO.write(outImage, "PNG", new File("/tmp/out.png"));
-    } catch (IOException ioe) {
-      ioe.printStackTrace();
-    }
-     */
-
     ResultPoint[] points;
     if (alignmentPattern == null) {
       points = new ResultPoint[] { bottomLeft, topLeft, topRight };      

javame/src/com/google/zxing/client/j2me/LCDUIImageMonochromeBitmapSource.java

@@ -17,6 +17,7 @@
 package com.google.zxing.client.j2me;
 
 import com.google.zxing.MonochromeBitmapSource;
+import com.google.zxing.BlackPointEstimationMethod;
 import com.google.zxing.common.BitArray;
 import com.google.zxing.common.BlackPointEstimator;
 
@@ -25,29 +26,22 @@ import javax.microedition.lcdui.Image;
 /**
  * <p>An implementation based on Java ME's {@link Image} representation.</p>
  * 
- * @author Sean Owen (srowen@google.com)
+ * @author Sean Owen (srowen@google.com), Daniel Switkin (dswitkin@google.com)
  */
 final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
 
   private final int[] rgbPixels;
-  private final int blackPoint;
   private final int width;
   private final int height;
+  private int blackPoint;
+  private BlackPointEstimationMethod lastMethod;
 
   LCDUIImageMonochromeBitmapSource(final Image image) {
-    int width = image.getWidth();
-    int height = image.getHeight();
-    this.width = width;
-    this.height = height;
-    int[] rgbPixels = new int[width * height];
-    this.rgbPixels = rgbPixels;
+    width = image.getWidth();
+    height = image.getHeight();
+    rgbPixels = new int[width * height];
     image.getRGB(rgbPixels, 0, width, 0, 0, width, height);
-    int[] luminanceBuckets = new int[32];
-    int minDimension = width < height ? width : height;
-    for (int n = 0, offset = 0; n < minDimension; n++, offset += width + 1) {
-      luminanceBuckets[computeRGBLuminance(rgbPixels[offset]) >> 3]++;
-    }
-    blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
+    blackPoint = 0x7F;
   }
 
   public boolean isBlack(int x, int y) {
@@ -76,6 +70,28 @@ final class LCDUIImageMonochromeBitmapSource implements MonochromeBitmapSource {
     return width;
   }
 
+  public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
+    if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
+      if (!BlackPointEstimationMethod.TWO_D_SAMPLING.equals(lastMethod)) {
+        int[] luminanceBuckets = new int[32];
+        int minDimension = width < height ? width : height;
+        for (int n = 0, offset = 0; n < minDimension; n++, offset += width + 1) {
+          luminanceBuckets[computeRGBLuminance(rgbPixels[offset]) >> 3]++;
+        }
+        blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
+      }
+    } else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
+      // TODO
+    } else {
+      throw new IllegalArgumentException("Unknown method: " + method);
+    }
+    lastMethod = method;
+  }
+
+  public BlackPointEstimationMethod getLastEstimationMethod() {
+    return lastMethod;
+  }
+
   /**
    * Extracts luminance from a pixel from this source. By default, the source is assumed to use RGB,
    * so this implementation computes luminance is a function of a red, green and blue components as

javase/src/com/google/zxing/client/j2se/BufferedImageMonochromeBitmapSource.java

@@ -17,6 +17,7 @@
 package com.google.zxing.client.j2se;
 
 import com.google.zxing.MonochromeBitmapSource;
+import com.google.zxing.BlackPointEstimationMethod;
 import com.google.zxing.common.BitArray;
 import com.google.zxing.common.BlackPointEstimator;
 
@@ -27,26 +28,17 @@ import java.awt.image.BufferedImage;
  * underlying image as if it were a monochrome image. Behind the scenes, it is evaluating
  * the luminance of the underlying image by retrieving its pixels' RGB values.</p>
  * 
- * @author srowen@google.com (Sean Owen)
+ * @author srowen@google.com (Sean Owen), Daniel Switkin (dswitkin@google.com)
  */
 public final class BufferedImageMonochromeBitmapSource implements MonochromeBitmapSource {
 
   private final BufferedImage image;
-  private final int blackPoint;
+  private int blackPoint;
+  private BlackPointEstimationMethod lastMethod;
 
   public BufferedImageMonochromeBitmapSource(BufferedImage image) {
     this.image = image;
-    int width = image.getWidth();
-    int height = image.getHeight();
-    int[] luminanceBuckets = new int[32];
-    int minDimension = width < height ? width : height;
-    int startI = height == minDimension ? 0 : (height - width) >> 1;
-    int startJ = width == minDimension ? 0 : (width - height) >> 1;
-    for (int n = 0; n < minDimension; n++) {
-      int pixel = image.getRGB(startJ + n, startI + n);
-      luminanceBuckets[computeRGBLuminance(pixel) >> 3]++;
-    }
-    blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
+    blackPoint = 0x7F;
   }
 
   public boolean isBlack(int x, int y) {
@@ -76,6 +68,33 @@ public final class BufferedImageMonochromeBitmapSource implements MonochromeBitm
     return image.getWidth();
   }
 
+  public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
+    if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
+      if (!BlackPointEstimationMethod.TWO_D_SAMPLING.equals(lastMethod)) {
+        int width = image.getWidth();
+        int height = image.getHeight();
+        int[] luminanceBuckets = new int[32];
+        int minDimension = width < height ? width : height;
+        int startI = height == minDimension ? 0 : (height - width) >> 1;
+        int startJ = width == minDimension ? 0 : (width - height) >> 1;
+        for (int n = 0; n < minDimension; n++) {
+          int pixel = image.getRGB(startJ + n, startI + n);
+          luminanceBuckets[computeRGBLuminance(pixel) >> 3]++;
+        }
+        blackPoint = BlackPointEstimator.estimate(luminanceBuckets) << 3;
+      }
+    } else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
+      // TODO
+    } else {
+      throw new IllegalArgumentException("Unknown method: " + method);
+    }
+    lastMethod = method;
+  }
+
+  public BlackPointEstimationMethod getLastEstimationMethod() {
+    return lastMethod;
+  }
+
   /**
    * Extracts luminance from a pixel from this source. By default, the source is assumed to use RGB,
    * so this implementation computes luminance is a function of a red, green and blue components as