Closes #157: Deskew before OCR

docs-core/src/main/java/com/sismics/docs/core/util/FileUtil.java

@@ -2,10 +2,9 @@ package com.sismics.docs.core.util;
 
 import com.sismics.docs.core.model.jpa.File;
 import com.sismics.tess4j.Tesseract;
+import com.sismics.util.ImageDeskew;
 import com.sismics.util.ImageUtil;
-import org.imgscalr.Scalr;
-import org.imgscalr.Scalr.Method;
-import org.imgscalr.Scalr.Mode;
+import com.sismics.util.Scalr;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -70,10 +69,13 @@ public class FileUtil {
             return null;
         }
         
-        // Upscale and grayscale the image
-        BufferedImage resizedImage = Scalr.resize(image, Method.AUTOMATIC, Mode.AUTOMATIC, 3500, Scalr.OP_ANTIALIAS, Scalr.OP_GRAYSCALE);
+        // Upscale, grayscale and deskew the image
+        BufferedImage resizedImage = Scalr.resize(image, Scalr.Method.AUTOMATIC, Scalr.Mode.AUTOMATIC, 3500, Scalr.OP_ANTIALIAS, Scalr.OP_GRAYSCALE);
         image.flush();
-        image = resizedImage;
+        ImageDeskew imageDeskew = new ImageDeskew(resizedImage);
+        BufferedImage deskewedImage = Scalr.rotate(resizedImage, - imageDeskew.getSkewAngle(), Scalr.OP_ANTIALIAS, Scalr.OP_GRAYSCALE);
+        resizedImage.flush();
+        image = deskewedImage;
 
         // OCR the file
         try {

docs-core/src/main/java/com/sismics/util/ImageDeskew.java

@@ -0,0 +1,167 @@
+package com.sismics.util;
+
+import java.awt.image.BufferedImage;
+
+/**
+ * <a url=http://www.jdeskew.com/>JDeskew</a>
+ */
+public class ImageDeskew {
+    /**
+     * Representation of a line in the image.
+     */
+    public class HoughLine {
+
+        // count of points in the line
+        public int count = 0;
+        // index in matrix.
+        public int index = 0;
+        // the line is represented as all x, y that solve y * cos(alpha) - x *
+        // sin(alpha) = d
+        public double alpha;
+        public double d;
+    }
+
+    // the source image
+    private BufferedImage cImage;
+    // the range of angles to search for lines
+    private double cAlphaStart = -20;
+    private double cAlphaStep = 0.2;
+    private int cSteps = 40 * 5;
+    // pre-calculation of sin and cos
+    private double[] cSinA;
+    private double[] cCosA;
+    // range of d
+    private double cDMin;
+    private double cDStep = 1.0;
+    private int cDCount;
+    // count of points that fit in a line
+    private int[] cHMatrix;
+
+    // constructor
+    public ImageDeskew(BufferedImage image) {
+        this.cImage = image;
+    }
+
+    // calculate the skew angle of the image cImage
+    public double getSkewAngle() {
+        ImageDeskew.HoughLine[] hl;
+        double sum = 0.0;
+        int count = 0;
+
+        // perform Hough Transformation
+        calc();
+        // top 20 of the detected lines in the image
+        hl = getTop(20);
+
+        if (hl.length >= 20) {
+            // average angle of the lines
+            for (int i = 0; i < 19; i++) {
+                sum += hl[i].alpha;
+                count++;
+            }
+            return (sum / count);
+        } else {
+            return 0.0d;
+        }
+    }
+
+    // calculate the count lines in the image with most points
+    private ImageDeskew.HoughLine[] getTop(int count) {
+
+        ImageDeskew.HoughLine[] hl = new ImageDeskew.HoughLine[count];
+        for (int i = 0; i < count; i++) {
+            hl[i] = new ImageDeskew.HoughLine();
+        }
+
+        ImageDeskew.HoughLine tmp;
+
+        for (int i = 0; i < (this.cHMatrix.length - 1); i++) {
+            if (this.cHMatrix[i] > hl[count - 1].count) {
+                hl[count - 1].count = this.cHMatrix[i];
+                hl[count - 1].index = i;
+                int j = count - 1;
+                while ((j > 0) && (hl[j].count > hl[j - 1].count)) {
+                    tmp = hl[j];
+                    hl[j] = hl[j - 1];
+                    hl[j - 1] = tmp;
+                    j--;
+                }
+            }
+        }
+
+        int alphaIndex;
+        int dIndex;
+
+        for (int i = 0; i < count; i++) {
+            dIndex = hl[i].index / cSteps; // integer division, no
+            // remainder
+            alphaIndex = hl[i].index - dIndex * cSteps;
+            hl[i].alpha = getAlpha(alphaIndex);
+            hl[i].d = dIndex + cDMin;
+        }
+
+        return hl;
+    }
+
+    // Hough Transformation
+    private void calc() {
+        int hMin = (int) ((this.cImage.getHeight()) / 4.0);
+        int hMax = (int) ((this.cImage.getHeight()) * 3.0 / 4.0);
+        init();
+
+        for (int y = hMin; y < hMax; y++) {
+            for (int x = 1; x < (this.cImage.getWidth() - 2); x++) {
+                // only lower edges are considered
+                if (ImageUtil.isBlack(this.cImage, x, y)) {
+                    if (!ImageUtil.isBlack(this.cImage, x, y + 1)) {
+                        calc(x, y);
+                    }
+                }
+            }
+        }
+
+    }
+
+    // calculate all lines through the point (x,y)
+    private void calc(int x, int y) {
+        double d;
+        int dIndex;
+        int index;
+
+        for (int alpha = 0; alpha < (this.cSteps - 1); alpha++) {
+            d = y * this.cCosA[alpha] - x * this.cSinA[alpha];
+            dIndex = (int) (d - this.cDMin);
+            index = dIndex * this.cSteps + alpha;
+            try {
+                this.cHMatrix[index] += 1;
+            } catch (Exception ex) {
+                System.out.println(ex.toString());
+            }
+        }
+    }
+
+    private void init() {
+
+        double angle;
+
+        // pre-calculation of sin and cos
+        this.cSinA = new double[this.cSteps - 1];
+        this.cCosA = new double[this.cSteps - 1];
+
+        for (int i = 0; i < (this.cSteps - 1); i++) {
+            angle = getAlpha(i) * Math.PI / 180.0;
+            this.cSinA[i] = Math.sin(angle);
+            this.cCosA[i] = Math.cos(angle);
+        }
+
+        // range of d
+        this.cDMin = -this.cImage.getWidth();
+        this.cDCount = (int) (2.0 * ((this.cImage.getWidth() + this.cImage.getHeight())) / this.cDStep);
+        this.cHMatrix = new int[this.cDCount * this.cSteps];
+
+    }
+
+    private double getAlpha(int index) {
+        return this.cAlphaStart + (index * this.cAlphaStep);
+    }
+}

docs-core/src/main/java/com/sismics/util/ImageUtil.java

@@ -1,19 +1,19 @@
 package com.sismics.util;
 
-import java.awt.image.BufferedImage;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.util.Iterator;
+import com.google.common.base.Charsets;
+import com.google.common.hash.Hashing;
+import com.sismics.util.mime.MimeType;
 
 import javax.imageio.IIOImage;
 import javax.imageio.ImageIO;
 import javax.imageio.ImageWriteParam;
 import javax.imageio.ImageWriter;
 import javax.imageio.stream.ImageOutputStream;
-
-import com.google.common.base.Charsets;
-import com.google.common.hash.Hashing;
-import com.sismics.util.mime.MimeType;
+import java.awt.image.BufferedImage;
+import java.awt.image.WritableRaster;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Iterator;
 
 /**
  * Image processing utilities.
@@ -34,7 +34,7 @@ public class ImageUtil {
         ImageWriter writer = null;
         ImageOutputStream imageOutputStream = null;
         try {
-            writer = (ImageWriter) iter.next();
+            writer = iter.next();
             ImageWriteParam iwp = writer.getDefaultWriteParam();
             iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
             iwp.setCompressionQuality(1.f);
@@ -69,7 +69,7 @@ public class ImageUtil {
      * Compute Gravatar hash.
      * See https://en.gravatar.com/site/implement/hash/.
      * 
-     * @param email
+     * @param email Email
      * @return Gravatar hash
      */
     public static String computeGravatar(String email) {
@@ -81,4 +81,40 @@ public class ImageUtil {
                 email.trim().toLowerCase(), Charsets.UTF_8)
                 .toString();
     }
+
+    public static boolean isBlack(BufferedImage image, int x, int y) {
+        if (image.getType() == BufferedImage.TYPE_BYTE_BINARY) {
+            WritableRaster raster = image.getRaster();
+            int pixelRGBValue = raster.getSample(x, y, 0);
+            return pixelRGBValue == 0;
+        }
+
+        int luminanceValue = 140;
+        return isBlack(image, x, y, luminanceValue);
+    }
+
+    public static boolean isBlack(BufferedImage image, int x, int y, int luminanceCutOff) {
+        int pixelRGBValue;
+        int r;
+        int g;
+        int b;
+        double luminance = 0.0;
+
+        // return white on areas outside of image boundaries
+        if (x < 0 || y < 0 || x > image.getWidth() || y > image.getHeight()) {
+            return false;
+        }
+
+        try {
+            pixelRGBValue = image.getRGB(x, y);
+            r = (pixelRGBValue >> 16) & 0xff;
+            g = (pixelRGBValue >> 8) & 0xff;
+            b = (pixelRGBValue) & 0xff;
+            luminance = (r * 0.299) + (g * 0.587) + (b * 0.114);
+        } catch (Exception e) {
+            // ignore.
+        }
+
+        return luminance < luminanceCutOff;
+    }
 }

docs-core/src/main/java/com/sismics/util/Scalr.java

@@ -0,0 +1,47 @@
+package com.sismics.util;
+
+import java.awt.*;
+import java.awt.geom.AffineTransform;
+import java.awt.image.BufferedImage;
+import java.awt.image.BufferedImageOp;
+import java.awt.image.ImagingOpException;
+
+public class Scalr extends org.imgscalr.Scalr {
+    /**
+     * Rotate an image by a specific amount.
+     *
+     * @param src Source image
+     * @param rotation Rotation angle
+     * @param ops Options
+     * @return Rotated image
+     * @throws IllegalArgumentException
+     * @throws ImagingOpException
+     */
+    public static BufferedImage rotate(BufferedImage src, double rotation, BufferedImageOp... ops) throws IllegalArgumentException, ImagingOpException {
+        long t = System.currentTimeMillis();
+        if (src == null) {
+            throw new IllegalArgumentException("src cannot be null");
+        } else {
+            if (DEBUG) {
+                log(0, "Rotating Image [%s]...", rotation);
+            }
+
+            AffineTransform tx = new AffineTransform();
+            tx.rotate(Math.toRadians(rotation));
+
+            BufferedImage result = createOptimalImage(src, src.getWidth(), src.getHeight());
+            Graphics2D g2d = result.createGraphics();
+            g2d.drawImage(src, tx, null);
+            g2d.dispose();
+            if (DEBUG) {
+                log(0, "Rotation Applied in %d ms, result [width=%d, height=%d]", System.currentTimeMillis() - t, result.getWidth(), result.getHeight());
+            }
+
+            if (ops != null && ops.length > 0) {
+                result = apply(result, ops);
+            }
+
+            return result;
+        }
+    }
+}

docs-web/src/main/webapp/src/partial/docs/document.edit.html

@@ -1,11 +1,6 @@
 <img src="img/loader.gif" ng-show="!document && isEdit()" />
 
 <div ng-show="document || !isEdit()">
-  <div class="row" ng-show="fileIsUploading">
-    <h4>{{ 'document.edit.uploading_files' | translate }}</h4>
-    <div class="col-md-6"><uib-progressbar value="fileProgress" class="progress-info active"></uib-progressbar></div>
-  </div>
-
   <form name="documentForm" class="form-horizontal">
     <div class="pull-right btn-group" ng-init="form = documentForm">
       <button type="submit" class="btn btn-primary" ng-disabled="!documentForm.$valid || fileIsUploading" ng-click="edit()">
@@ -17,6 +12,11 @@
 
     <div uib-alert ng-class="'alert-' + alert.type" ng-repeat="alert in alerts" type="alert.type" close="closeAlert($index)">{{ alert.msg }}</div>
 
+    <div class="row" ng-show="fileIsUploading">
+      <h4>{{ 'document.edit.uploading_files' | translate }}</h4>
+      <div class="col-md-6"><uib-progressbar value="fileProgress" class="progress-info active"></uib-progressbar></div>
+    </div>
+
     <fieldset>
       <legend>{{ 'document.edit.primary_metadata' | translate }}</legend>
       <div class="form-group" ng-class="{ 'has-error': !documentForm.title.$valid && documentForm.$dirty }">