OCR on OS X with tesseract

ocr.markdown

Install ImageMagick for image conversion:

brew install imagemagick

Install tesseract for OCR:

brew install tesseract --all-languages

Or install without --all-languages and install them manually as needed.

Make sure the input image is a grayscale .tif and fairly large. ~500x150 was too small, while ~2000*500 worked very well.

convert input.png -resize 400% -type Grayscale input.tif

OCR it. The default language is English. Language codes are 3 chars per man tesseract.

tesseract -l eng input.tif output

This creates output.txt.

Does converting a png to tiff increase the odds of accurate OCR?

It's working thanks for the help

A long time ago, I installed tesseract 3.05.01 for OCR using HomeBrew:

brew install --with-training-tools tesseract

How do I update it to the latest? I thought by regularly running the following, this would be done:

brew update
brew upgrade
brew outdated

However, my tesseract has not been updated at all...

@flyingmrwang did you figure it out? I encountered same issue.

Love this tip. I created a bash function to make it even easier to run on english text:

function extract-text {
    FILEPATH=$1
    convert $1 -resize 400% -type Grayscale $1.tif
    tesseract -l eng $1.tif output
}

For imagemagick: stable 7.0.8-14 on OS X 10.9.5 I had to install with --with-fontconfig:

brew install imagemagick --with-fontconfig

Compare your results with/without resize as resize can take more resources for no OCR improvement.

For OCR improvements see Improving Quality or try training.

Is there a brew route for getting & running the latest version of tesseract (LSTM-based, 4.0.0)?

I'm currently using:

$ tesseract --version                                                                                                   
tesseract 3.05.01
 leptonica-1.74.4
  libjpeg 9c : libpng 1.6.34 : libtiff 4.0.9 : zlib 1.2.11

..on macOS, High Sierra 10.13.4 17E202 x86_64. Thanks!

All languages option is not working

brew install tesseract --all-languages
Error: invalid option: --all-languages

brew --version
Homebrew 2.0.0
Homebrew/homebrew-core (git revision a761; last commit 2019-02-05)
Homebrew/homebrew-cask (git revision 1e6e6; last commit 2019-02-05)

@gabedot

Homebrew recently decided to remove all options from the homebrew-core Formula's. Though as of right now tesseract now includes all languages by default so just remove the option and you should get all languages. This makes tesseract 680MB by default though so think this should change in the future.

In the medium to short term, you can install tesseract with all language support with this
brew install https://github.com/Homebrew/homebrew-core/raw/10708da5492fa4da6fbf2618210681953219409f/Formula/tesseract.rb though that's just a reference to a particular version of the Formula so won't receive future updates.

why my execute brew install tesseract --all-languages is Error: invalid option: --all-languages ?

why my execute brew install tesseract --all-languages is Error: invalid option: --all-languages ?

Homebrew recently decided to remove all options from the homebrew-core Formula's as explained by @varenc

Hi, I have installed tessaract 4.0.0 smoothly by
brew install tesseract
but have only these languages available:
$ tesseract --list-langs List of available languages (3): eng osd snum
No above mention option like --with-all-languates does not work anymore :-/

Is there a way to install selected language(s)? Thanks!

Answering my own question:
brew install tesseract-lang
It installs most of the languages, but not all listed here: link
I need to install language "equ", still don't know how

thanks @bejvisek

MacOS user must use "brew install tesseract-lang" instant "brew install tesseract --all-languages"