Processing with OCR

This is a short Processing sketch to demonstrate the use optical character recognition (OCR) with the Tesseract OCR engine. I used the Mac OSX platform for testing. Here are the steps.

Install the Tesseract in OSX with all supported languages by using Homebrew

brew install imagemagick
brew install tesseract --all-languages

Install the Java JNA binding from Tess4j
I just download and unzip the package. From the dist folder, I copy the tess4j.jar to the code folder of the Processing sketch.

Install the jai_imageio.jar
It also needs the Java Advanced Imaging Image Tools from the Java archive. Copy the jai_imageio.jar from the lib folder to the code folder of the Processing sketch.

Copy the dynamic libraries
I also copy the libtesseract.dylib, liblept.dylib from the Homebrew directories to the code folder of the Processing sketch, with their loading path patched with the @loader_path.

Copy the trained language data
Finally, I copy the English trained language file, eng.traineddata, from the Homebrew directory to the data folder of the sketch. It also needs a sub-folder named tessdata.

Here is the testing result. The top section is the original test image in PNG format (400 x 300). The bottom section is the recognised string with each character shown one by one in the program.

The complete source code

import net.sourceforge.tess4j.*;
import java.awt.image.BufferedImage;
Tesseract ocr;
BufferedImage img;
PImage pimg;
String res, show;
int idx;
void setup() {
  size(400, 600);
  ocr = new Tesseract();
  pimg = loadImage("testing.png");
  img = (BufferedImage) pimg.getNative();
  show = "";
  idx = 0;
  try {
    res = ocr.doOCR(img);
    //   println(res);
  catch (TesseractException e) {
void draw() {
  image(pimg, 0, 0);
  if (idx < res.length()) {
    show += res.charAt(idx);
  } else {
  text(show, 20, pimg.height+30);

The only mistake I can spot is ‘ocr’ becomes ‘cor’.