import com.google.zxing.BlackPointEstimationMethod;
import com.google.zxing.MonochromeBitmapSource;
+import com.google.zxing.ReaderException;
import com.google.zxing.common.BitArray;
import com.google.zxing.common.BlackPointEstimator;
+import java.awt.geom.AffineTransform;
+import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
+import java.awt.image.BufferedImageOp;
/**
* <p>An implementation based upon {@link BufferedImage}. This provides access to the
* 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>
*
+ * <p>This may also be used to construct a {@link MonochromeBitmapSource}
+ * based on a region of a {@link BufferedImage}; see
+ * {@link #BufferedImageMonochromeBitmapSource(BufferedImage, int, int, int, int)}.</p>
+ *
* @author srowen@google.com (Sean Owen), Daniel Switkin (dswitkin@google.com)
*/
public final class BufferedImageMonochromeBitmapSource implements MonochromeBitmapSource {
private final BufferedImage image;
+ private final int left;
+ private final int top;
+ private final int width;
+ private final int height;
private int blackPoint;
private BlackPointEstimationMethod lastMethod;
private int lastArgument;
private static final int LUMINANCE_SHIFT = 8 - LUMINANCE_BITS;
private static final int LUMINANCE_BUCKETS = 1 << LUMINANCE_BITS;
+ /**
+ * Creates an instance that uses the entire given image as a source of pixels to decode.
+ *
+ * @param image image to decode
+ */
public BufferedImageMonochromeBitmapSource(BufferedImage image) {
+ this(image, 0, 0, image.getWidth(), image.getHeight());
+ }
+
+ /**
+ * Creates an instance that uses only a region of the given image as a source of pixels to decode.
+ *
+ * @param image image to decode a region of
+ * @param left x coordinate of leftmost pixels to decode
+ * @param top y coordinate of topmost pixels to decode
+ * @param right one more than the x coordinate of rightmost pixels to decode. That is, we will decode
+ * pixels whose x coordinate is in [left,right)
+ * @param bottom likewise, one more than the y coordinate of the bottommost pixels to decode
+ */
+ public BufferedImageMonochromeBitmapSource(BufferedImage image, int left, int top, int right, int bottom) {
this.image = image;
blackPoint = 0x7F;
lastMethod = null;
lastArgument = 0;
+ int sourceHeight = image.getHeight();
+ int sourceWidth = image.getWidth();
+ if (left < 0 || top < 0 || right > sourceWidth || bottom > sourceHeight || right <= left || bottom <= top) {
+ throw new IllegalArgumentException("Invalid bounds: (" + top + ',' + left + ") (" + right + ',' + bottom + ')');
+ }
+ this.left = left;
+ this.top = top;
+ this.width = right - left;
+ this.height = bottom - top;
+ }
+
+ /**
+ * @return underlying {@link BufferedImage} behind this instance. Note that even if this instance
+ * only uses a subset of the full image, the returned value here represents the entire backing image.
+ */
+ public BufferedImage getImage() {
+ return image;
+ }
+
+ private int getRGB(int x, int y) {
+ return image.getRGB(left + x, top + y);
+ }
+
+ private void getRGBRow(int startX, int startY, int[] result) {
+ image.getRGB(left + startX, top + startY, result.length, 1, result, 0, result.length);
}
public boolean isBlack(int x, int y) {
- return computeRGBLuminance(image.getRGB(x, y)) < blackPoint;
+ return computeRGBLuminance(getRGB(x, y)) < blackPoint;
}
public BitArray getBlackRow(int y, BitArray row, int startX, int getWidth) {
- if (row == null) {
+ if (row == null || row.getSize() < getWidth) {
row = new BitArray(getWidth);
} else {
row.clear();
}
- int[] pixelRow = image.getRGB(startX, y, getWidth, 1, null, 0, getWidth);
- for (int i = 0; i < getWidth; i++) {
- if (computeRGBLuminance(pixelRow[i]) < blackPoint) {
- row.set(i);
+ int[] pixelRow = new int[getWidth];
+ getRGBRow(startX, y, pixelRow);
+
+ // If the current decoder calculated the blackPoint based on one row, assume we're trying to
+ // decode a 1D barcode, and apply some sharpening.
+ // TODO: We may want to add a fifth parameter to request the amount of shapening to be done.
+ if (lastMethod.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
+ int left = computeRGBLuminance(pixelRow[0]);
+ int center = computeRGBLuminance(pixelRow[1]);
+ for (int i = 1; i < getWidth - 1; i++) {
+ int right = computeRGBLuminance(pixelRow[i + 1]);
+ // Simple -1 4 -1 box filter with a weight of 2
+ int luminance = ((center << 2) - left - right) >> 1;
+ if (luminance < blackPoint) {
+ row.set(i);
+ }
+ left = center;
+ center = right;
+ }
+ } else {
+ for (int i = 0; i < getWidth; i++) {
+ if (computeRGBLuminance(pixelRow[i]) < blackPoint) {
+ row.set(i);
+ }
}
}
return row;
}
public int getHeight() {
- return image.getHeight();
+ return height;
}
public int getWidth() {
- return image.getWidth();
+ return width;
}
- public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) {
+ public void estimateBlackPoint(BlackPointEstimationMethod method, int argument) throws ReaderException {
if (!method.equals(lastMethod) || argument != lastArgument) {
- int width = image.getWidth();
- int height = image.getHeight();
int[] histogram = new int[LUMINANCE_BUCKETS];
- float biasTowardsWhite = 1.0f;
if (method.equals(BlackPointEstimationMethod.TWO_D_SAMPLING)) {
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);
+ int pixel = getRGB(startJ + n, startI + n);
histogram[computeRGBLuminance(pixel) >> LUMINANCE_SHIFT]++;
}
} else if (method.equals(BlackPointEstimationMethod.ROW_SAMPLING)) {
if (argument < 0 || argument >= height) {
throw new IllegalArgumentException("Row is not within the image: " + argument);
}
- biasTowardsWhite = 2.0f;
int[] rgbArray = new int[width];
- image.getRGB(0, argument, width, 1, rgbArray, 0, width);
+ getRGBRow(0, argument, rgbArray);
for (int x = 0; x < width; x++) {
histogram[computeRGBLuminance(rgbArray[x]) >> LUMINANCE_SHIFT]++;
}
} else {
throw new IllegalArgumentException("Unknown method: " + method);
}
- blackPoint = BlackPointEstimator.estimate(histogram, biasTowardsWhite) << LUMINANCE_SHIFT;
+ blackPoint = BlackPointEstimator.estimate(histogram) << LUMINANCE_SHIFT;
lastMethod = method;
lastArgument = argument;
}
return lastMethod;
}
+ public MonochromeBitmapSource rotateCounterClockwise() {
+ if (!isRotateSupported()) {
+ throw new IllegalStateException("Rotate not supported");
+ }
+ int sourceWidth = image.getWidth();
+ int sourceHeight = image.getHeight();
+ // 90 degrees counterclockwise:
+ AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);
+ BufferedImageOp op = new AffineTransformOp(transform, AffineTransformOp.TYPE_NEAREST_NEIGHBOR);
+ // Note width/height are flipped since we are rotating 90 degrees:
+ BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, image.getType());
+ op.filter(image, rotatedImage);
+ return new BufferedImageMonochromeBitmapSource(rotatedImage,
+ top,
+ sourceWidth - (left + width),
+ top + height,
+ sourceWidth - left);
+ }
+
+ public boolean isRotateSupported() {
+ // Can't run AffineTransforms on images of unknown format
+ return image.getType() != BufferedImage.TYPE_CUSTOM;
+ }
+
/**
* 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
projects / zxing.git / blobdiff