Added image processing example for Node

Author: Balearica

examples/node/image-processing.js

@@ -0,0 +1,35 @@
+#!/usr/bin/env node
+const path = require('path');
+const fs = require('fs');
+const { createWorker } = require('../../');
+
+const [,, imagePath] = process.argv;
+const image = path.resolve(__dirname, (imagePath || '../data/meditations.jpg'));
+
+console.log(`Recognizing ${image}`);
+
+// Tesseract.js returns images (imageColor, imageGrey, imageBinary) as strings 
+// to be used as source tags.
+// This function converts to Uint8Array data for saving to disk. 
+const convertImage = (imageSrc) => {
+  const data = atob(imageSrc.split(',')[1])
+        .split('')
+        .map((c) => c.charCodeAt(0));
+
+  return new Uint8Array(data);
+}
+
+(async () => {
+  const worker = await createWorker();
+  await worker.loadLanguage('eng');
+  await worker.initialize('eng');
+  const { data: { imageColor, imageGrey, imageBinary } } = await worker.recognize(image, {rotateAuto: true}, {imageColor: true, imageGrey: true, imageBinary: true});
+  
+  console.log('Saving intermediate images: imageColor.png, imageGrey.png, imageBinary.png');
+
+  fs.writeFileSync('imageColor.png', convertImage(imageColor));
+  fs.writeFileSync('imageGrey.png', convertImage(imageGrey));
+  fs.writeFileSync('imageBinary.png', convertImage(imageBinary));
+
+  await worker.terminate();
+})();