I updated tesseract-ios-lib with a (fake) armv7s slice. There is no need to remove armv7s from build architectures anymore. More informations about this change on my previous post.

Introduction

In my last article about how to compile tesseract for iOS SDK 6, I quickly posted two links to my github repos:

• tesseract-ios: an Objective-C wrapper for tesseract
• tesseract-ios-lib: the tesseract library compiled for iOS (universal armv7/i386 library)

Some comments complained about the lack of guide to install and use this wrapper. I’m going to show you how to build a new iOS project with tesseract, from scratch.

Create the project

Create a simple Single View Application from XCode:

Name it whatever you want:

Project structure

Download tesseract-ios, tesseract-ios-lib, and your language trained data.

Then, open your project folder in Finder, and organise it like this:

Add “tesseract-ios” and “tesseract-ios-lib” in your project by creating groups:

Then, add “tessdata” by reference:

This step is extremely important, double check that you’re adding it by reference or your application will crash.

Project settings

Go to your project configuration, select your target, and click on “Build Settings”. Then, set the C++ compiler to default:

And set the build architecture to “armv7″ (instead of “armv7 armv7s”, as tesseract-ios-lib doesn’t contain an armv7s slice for now):

We’re ready to use tesseract.

Usage

Add an image called “image_sample.jpg” to your project.

Then, in ViewController.m, add #import tesseract.h and put the following lines in -viewDidLoad:

Methods reference is available on the project repo.

You should get the image-extracted text in your console.

Project code

You can download the tutorial source code right here: TesseractSample.

Added instructions to integrate an armv7s slice in liblept.a and libtesseract_all.a.

Update 09/24/12

To make the iOS integration easier, I made a Github repo containing an Objective-C wrapper for Tesseract. It relies on an other repo containing tesseract & leptonica libs. Feel free to improve them !

• Objective-C wrapper: https://github.com/ldiqual/tesseract-ios
• Compiled libraries: https://github.com/ldiqual/tesseract-ios-lib

More informations about these repos on my next article.

Introduction

I had troubles while following the compiling guide from this blog: http://tinsuke.wordpress.com/2011/11/01/how-to-compile-and-use-tesseract-3-01-on-ios-sdk-5/. Some dependencies are missing on a fresh Mountain Lion with Xcode 4.5, and more importantly: the build_dependencies.sh won’t work.

Here is why: Xcode 4.5 and iOS SDK 6.0 don’t support armv6 anymore.

So here are the steps to build tesseract-ocr for iOS SDK 6.0.

Requirements

If you don’t have HomeBrew already, that’s a shame. Run to this website and install it.

Then, install libtool and automake:

You should have installed ‘Command Line Tools’ after the Homebrew installation, but if you forgot: Open Xcode’s preferences, and install them from the ‘Downloads’ tab.

The build process will need libtoolize. Just make a symlink to glibtoolize:

We’re good to go.

Sources and compilation

The steps will more or less follow the tinsuke’s article, except for one thing: the build script.

Get the following sources:

• tesseract: http://code.google.com/p/tesseract-ocr/downloads/detail?name=tesseract-3.01.tar.gz
• leptonica: http://www.leptonica.com/source/leptonica-1.69.tar.gz
• build_dependencies.sh: https://gist.github.com/3763217 (click on “raw” and save it to your computer)

Then, organize your folder with the following structure:

You might want to modify build_dependencies.sh to make LEPTON_LIB and TESSERACT_LIB match the proper folders.

Now, you can build the libraries:

In dependencies/lib/, you’ll find liblept.a and libtesseract_all.a, these are the only libraries you need so you can remove other ones. Both contain armv7 and i386 slices only, but many iOS 5 projects require an armv7s slice.

Just follow this Matt Galloway’s blog post to generate and put an armv7s slice into the libs.

Now you just have to copy dependencies/ in your Xcode Project, and follow my next article on how to use tesseract.