Closes #157: Deskew before OCR

This commit is contained in:
Benjamin Gamard 2017-11-12 14:49:52 +01:00
parent 46079393d5
commit dca8c28b84
5 changed files with 273 additions and 21 deletions

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

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@ -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);
}
}

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@ -1,19 +1,19 @@
package com.sismics.util; package com.sismics.util;
import java.awt.image.BufferedImage; import com.google.common.base.Charsets;
import java.io.IOException; import com.google.common.hash.Hashing;
import java.io.OutputStream; import com.sismics.util.mime.MimeType;
import java.util.Iterator;
import javax.imageio.IIOImage; import javax.imageio.IIOImage;
import javax.imageio.ImageIO; import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam; import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter; import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream; import javax.imageio.stream.ImageOutputStream;
import java.awt.image.BufferedImage;
import com.google.common.base.Charsets; import java.awt.image.WritableRaster;
import com.google.common.hash.Hashing; import java.io.IOException;
import com.sismics.util.mime.MimeType; import java.io.OutputStream;
import java.util.Iterator;
/** /**
* Image processing utilities. * Image processing utilities.
@ -34,7 +34,7 @@ public class ImageUtil {
ImageWriter writer = null; ImageWriter writer = null;
ImageOutputStream imageOutputStream = null; ImageOutputStream imageOutputStream = null;
try { try {
writer = (ImageWriter) iter.next(); writer = iter.next();
ImageWriteParam iwp = writer.getDefaultWriteParam(); ImageWriteParam iwp = writer.getDefaultWriteParam();
iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT); iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwp.setCompressionQuality(1.f); iwp.setCompressionQuality(1.f);
@ -69,7 +69,7 @@ public class ImageUtil {
* Compute Gravatar hash. * Compute Gravatar hash.
* See https://en.gravatar.com/site/implement/hash/. * See https://en.gravatar.com/site/implement/hash/.
* *
* @param email * @param email Email
* @return Gravatar hash * @return Gravatar hash
*/ */
public static String computeGravatar(String email) { public static String computeGravatar(String email) {
@ -81,4 +81,40 @@ public class ImageUtil {
email.trim().toLowerCase(), Charsets.UTF_8) email.trim().toLowerCase(), Charsets.UTF_8)
.toString(); .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;
}
} }

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@ -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;
}
}
}

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