Issue 677, faster grayscale conversion from Wolfgang

git-svn-id: https://zxing.googlecode.com/svn/trunk@1697 59b500cc-1b3d-0410-9834-0bbf25fbcc57

AUTHORS

@@ -59,4 +59,5 @@ Suraj Supekar
 Sven Klinkhamer
 Thomas Gerbet
 Vince Francis (LifeMarks)
+Wolfgang Jung
 Yakov Okshtein (Google)

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

@@ -19,28 +19,27 @@ package com.google.zxing.client.j2se;
 import com.google.zxing.LuminanceSource;
 
 import java.awt.Graphics2D;
-import java.awt.image.BufferedImage;
 import java.awt.geom.AffineTransform;
+import java.awt.image.BufferedImage;
 
 /**
  * This LuminanceSource implementation is meant for J2SE clients and our blackbox unit tests.
  *
  * @author dswitkin@google.com (Daniel Switkin)
  * @author Sean Owen
+ * @author code@elektrowolle.de (Wolfgang Jung)
  */
 public final class BufferedImageLuminanceSource extends LuminanceSource {
 
   private final BufferedImage image;
   private final int left;
   private final int top;
-  private int[] rgbData;
 
   public BufferedImageLuminanceSource(BufferedImage image) {
     this(image, 0, 0, image.getWidth(), image.getHeight());
   }
 
-  public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width,
-      int height) {
+  public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width, int height) {
     super(width, height);
 
     int sourceWidth = image.getWidth();
@@ -48,14 +47,13 @@ public final class BufferedImageLuminanceSource extends LuminanceSource {
     if (left + width > sourceWidth || top + height > sourceHeight) {
       throw new IllegalArgumentException("Crop rectangle does not fit within image data.");
     }
-
-    this.image = image;
+    // Create a grayscale copy, no need to calculate the luminance manually
+    this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY);
+    this.image.getGraphics().drawImage(image, 0, 0, null);
     this.left = left;
     this.top = top;
   }
 
-  // These methods use an integer calculation for luminance derived from:
-  // <code>Y = 0.299R + 0.587G + 0.114B</code>
   @Override
   public byte[] getRow(int y, byte[] row) {
     if (y < 0 || y >= getHeight()) {
@@ -65,19 +63,8 @@ public final class BufferedImageLuminanceSource extends LuminanceSource {
     if (row == null || row.length < width) {
       row = new byte[width];
     }
-
-    if (rgbData == null || rgbData.length < width) {
-      rgbData = new int[width];
-    }
-    image.getRGB(left, top + y, width, 1, rgbData, 0, width);
-    for (int x = 0; x < width; x++) {
-      int pixel = rgbData[x];
-      int luminance = (306 * ((pixel >> 16) & 0xFF) +
-          601 * ((pixel >> 8) & 0xFF) +
-          117 * (pixel & 0xFF) +
-          (0x200)) >> 10; // 0x200 = 1<<9, half an lsb of the result to force rounding
-      row[x] = (byte) luminance;
-    }
+    // The underlying raster of image consists of bytes with the luminance values
+    image.getRaster().getDataElements(left, top + y, width, 1, row);
     return row;
   }
 
@@ -87,20 +74,8 @@ public final class BufferedImageLuminanceSource extends LuminanceSource {
     int height = getHeight();
     int area = width * height;
     byte[] matrix = new byte[area];
-
-    int[] rgb = new int[area];
-    image.getRGB(left, top, width, height, rgb, 0, width);
-    for (int y = 0; y < height; y++) {
-      int offset = y * width;
-      for (int x = 0; x < width; x++) {
-        int pixel = rgb[offset + x];
-        int luminance = (306 * ((pixel >> 16) & 0xFF) +
-            601 * ((pixel >> 8) & 0xFF) +
-            117 * (pixel & 0xFF) +
-            (0x200)) >> 10; // 0x200 = 1<<9, half an lsb of the result to force rounding
-        matrix[offset + x] = (byte) luminance;
-      }
-    }
+    // The underlying raster of image consists of area bytes with the luminance values
+    image.getRaster().getDataElements(left, top, width, height, matrix);
     return matrix;
   }
 
@@ -114,17 +89,21 @@ public final class BufferedImageLuminanceSource extends LuminanceSource {
     return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height);
   }
 
-  // Can't run AffineTransforms on images of unknown format.
+  /**
+   * This is always true, since the image is a gray-scale image.
+   *
+   * @return true
+   */
   @Override
   public boolean isRotateSupported() {
-    return image.getType() != BufferedImage.TYPE_CUSTOM;
+    return true;
   }
 
   @Override
   public LuminanceSource rotateCounterClockwise() {
-    if (!isRotateSupported()) {
-      throw new IllegalStateException("Rotate not supported");
-    }
+    //if (!isRotateSupported()) {
+    //  throw new IllegalStateException("Rotate not supported");
+    //}
     int sourceWidth = image.getWidth();
     int sourceHeight = image.getHeight();
 
@@ -132,7 +111,7 @@ public final class BufferedImageLuminanceSource extends LuminanceSource {
     AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);
 
     // Note width/height are flipped since we are rotating 90 degrees.
-    BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, image.getType());
+    BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY);
 
     // Draw the original image into rotated, via transformation
     Graphics2D g = rotatedImage.createGraphics();
@@ -141,8 +120,7 @@ public final class BufferedImageLuminanceSource extends LuminanceSource {
 
     // Maintain the cropped region, but rotate it too.
     int width = getWidth();
-    return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width),
-        getHeight(), width);
+    return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);
   }
 
 }