tess-two

A fork of Tesseract Tools for Android (tesseract-android-tools) that adds some additional functions. Tesseract Tools for Android is a set of Android APIs and build files for the Tesseract OCR and Leptonica image processing libraries.

This project works with Tesseract pre-release v3.04 and Leptonica v1.72. The required source code for Tesseract and Leptonica is included within the tess-two/jni folder.

The tess-two subdirectory contains tools for compiling the Tesseract and Leptonica libraries for use on the Android platform. It contains an Android library project that provides a Java API for accessing natively-compiled Tesseract and Leptonica APIs.

The eyes-two subdirectory contains a second, separate library project with additional image processing code copied from the eyes-free project. It includes native functions for text detection, blur detection, optical flow detection, and thresholding. Building eyes-two is not necessary for using the Tesseract or Leptonica APIs.

The tess-two-test subdirectory contains Android JUnit tests.

Pre-requisites

• Android 2.2 or higher
• A v3.02 trained data file for a language. Data files must be extracted to the Android device in a subdirectory named tessdata.

Versions

Release points are tagged with version numbers. A change to the major version number indicates an API change making that version incompatible with previous versions.

Building

This project is set up to build on Android SDK Tools r22.3+ and Android NDK r10d+. The build works on Linux, Mac OS X, and Windows 7/8. See Issues for reported build issues.

On 64-bit Ubuntu, you may need to install the ia32-libs 32-bit compatibility library.

To build the latest tess-two code, run the following commands in the terminal:

git clone git://github.com/rmtheis/tess-two tess
cd tess
cd tess-two
ndk-build
android update project --path .
ant release

To build eyes-two, additionally run the following:

cd ..
cd eyes-two
ndk-build
android update project --path .
ant release

After building, the tess-two and eyes-two projects can be imported into Eclipse using File->Import->Existing Projects into Workspace.

Gradle build

This project can also be built using Gradle, tested and installed into a (local) Maven repository.

Prerequisites

Building the project through Gradle requires the NDK to be installed through the Android SDK manager. The build system will look for the NDK in $ANDROID_HOME/ndk-bundle/

A file local.properties needs to be created with the location of your android SDK, the contents of this file should be:

sdk.dir=<path to Android SDK>

Building

The project can be built using the following command:

./gradlew build

This produces a release and debug AAR file in tess-two/build/outputs/aar/

Installing in Maven

The group and artifact ID's are:

Release version: groupId: com.googlecode.tesseract.android artifactId: tess-two version: 5.2.0-SNAPSHOT packaging: aar

Debug version groupId: com.googlecode.tesseract.android artifactId: tess-two-debug version: 5.2.0-SNAPSHOT packaging: aar

Both the debug and release builds can be installed as artifacts in a Maven repository of your choosing.

To install the debug build into your local repository run the following command:

./gradlew publishDebugPublicationToMavenLocal 

To install the release build into your local repository run the following command:

./gradlew publishReleasePublicationToMavenLocal

To install the build into a remote repository the following configuration items need to be added to your ~/.gradle/gradle.properties file

mavenSnapshots=<url>
mavenSnapshotsUsername=<username>
mavenSnapshotsPassword=<password>
mavenReleases=<url>
mavenReleasesUsername=<username>
mavenReleasesPassword=<password>

To install into a maven repository, run one of the following commands:

Debug/Release	Snapshots/Releases	Command
Debug	Snapshot	./gradlew publishDebugPublicationToTess-two-snapshotsRepository
Debug	Releases	./gradlew publishDebugPublicationToTess-two-releasesRepository
Release	Snapshot	./gradlew publishReleasePublicationToTess-two-snapshotsRepository
Release	Releases	./gradlew publishReleasePublicationToTess-two-releasesRepository

Depending on tess-two from Gradle

To use tess-two as a dependency in your Android Gradle project make sure the following lines are in your gradle build files:

app/build.gradle:

dependencies { 
    compile 'com.googlecode.tesseract.android:tess-two:5.2.0-SNAPSHOT'  
    // other dependencies
}

build.gradle:

allprojects {
    repositories {
        mavenLocal()
        // other repo's
    }
}

Maven

While this project does not require Maven (and this project has not yet been registered in a Maven central repository), it can be integrated into a local Maven repository for convenience.

ProGuard

If you're using ProGuard for code shrinking and obfuscation, add the following to your app's ProGuard config to retain fields used for sharing data with native code:

# tess-two
-keep class com.googlecode.leptonica.android.Box {
    private long mNativeBox;
}
-keep class com.googlecode.leptonica.android.Boxa {
    private long mNativeBoxa;
}
-keep class com.googlecode.leptonica.android.Pix {
    private long mNativePix;
}
-keep class com.googlecode.leptonica.android.Pixa {
    private long mNativePixa;
}
-keep class com.googlecode.tesseract.android.TessBaseAPI {
    private long mNativeData;
}
-keep class com.googlecode.tesseract.android.PageIterator {
    private long mNativePageIterator;
}
-keep class com.googlecode.tesseract.android.ResultIterator {
    private long mNativeResultIterator;
}

# eyes-two
-keep class com.googlecode.eyesfree.textdetect.HydrogenTextDetector {
    private long mNative;
}

Support

• Stack Overflow: http://stackoverflow.com/questions/tagged/tess-two
• tesseract-ocr: https://groups.google.com/forum/#!forum/tesseract-ocr

If you've found an error in this project, please file an issue.

Patches are encouraged, and may be submitted by forking this project and submitting a pull request through GitHub.

License

Copyright 2011 Robert Theis

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.