// Copyright (c) 2017 The Regents of the University of California.
// All rights reserved.
// Permission is hereby granted, without written agreement and without
// license or royalty fees, to use, copy, modify, and distribute this
// software and its documentation for any purpose, provided that the above
// copyright notice and the following two paragraphs appear in all copies
// of this software.
// IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
// ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
// THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
// THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
// PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
// CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
// ENHANCEMENTS, OR MODIFICATIONS.
/** An optical character detection accessor. This accessor takes an input image
* and attempts to recognize text in the image. It considers the whole image,
* so it works best if the image is pre-cropped to the portion containing only
* text.
*
* This accessor uses Tesseract.js, an open source optical character
* recognition tool, available under the Apache 2.0 license.
* http://tesseract.projectnaptha.com/
*
* @accessor image/CharacterDetection
* @input input An image
* @input (JSON) options A JSON object of options. See:
* https://github.com/naptha/tesseract.js/blob/master/docs/tesseract_parameters.md
* @output {String} text A string of any text recognized in the image.
* @author Elizabeth Osyk
* @version $$Id$$
*/
// FIXME: Handle options. Does nothing currently.
// TODO: Add output for meta-information? (E.g. detection quality)
// TODO: Add output with image showing where the text was found?
// Stop extra messages from jslint. Note that there should be no
// space between the / and the * and global.
/*globals addInputHandler, console, exports, get, getParameter, input, output, removeInputHandler, require, send */
/*jshint globalstrict: true */
"use strict";
var Tesseract = null;
try {
Tesseract = require('tesseract');
} catch (error) {
console.log("The tesseract module was not present. The CharacterRecognition accessor is not supported on this accessor host.");
}
exports.setup = function () {
this.input('input');
this.input('options'); // FIXME: Handle options. Does nothing currently.
this.output('text', {
'type': 'string'
});
};
exports.initialize = function () {
var self = this;
this.window = {};
this.addInputHandler('input', function () {
var image = this.get('input');
Tesseract.recognize(image)
// Optionally: Log progress.
// .progress(function(p) {console.log('progress', p);})
.then(function (result) {
self.send('text', result.text);
});
});
};