textract/lib/extractors/images.js

Extracting text from files of various type including html, pdf, doc, docx, xls, xlsx, csv, pptx, png, jpg, gif, rtf, text/*, and various open office.

var exec = require( 'child_process' ).exec
  , util = require( '../util' )
  ;

function tesseractExtractionCommand( options, inputFile, outputFile ) {
  var cmd = 'tesseract ' + inputFile + ' ' + outputFile;
  if ( options.tesseract ) {
    if ( options.tesseract.lang ) {
      cmd += ' -l ' + options.tesseract.lang;
    } else if ( options.tesseract.cmd ) {
      cmd += ' ' + options.tesseract.cmd;
    }
  }
  cmd += ' quiet';
  return cmd;
}

function extractText( filePath, options, cb ) {
  var execOptions = util.createExecOptions( 'images', options );
  util.runExecIntoFile( 'tesseract', filePath, options,
    execOptions, tesseractExtractionCommand, cb );
}

function testForBinary( options, cb ) {
  exec( 'tesseract',
    function( error, stdout, stderr ) {
      var msg;
      // checking for content of help text
      if ( ( error && error.toString().indexOf( 'Usage:' ) > -1 ) ||
          ( stderr && stderr.toString().indexOf( 'Usage:' ) > -1 ) ||
          ( stdout && stdout.toString().indexOf( 'Usage:' ) > -1 ) ) {
        cb( true );
      } else {
        msg = 'INFO: \'tesseract\' does not appear to be installed, ' +
         'so textract will be unable to extract images.';
        cb( false, msg );
      }
    }
  );
}

module.exports = {
  types: ['image/png', 'image/jpeg', 'image/gif'],
  extract: extractText,
  test: testForBinary
};