Node.JS Azure Function to resize images, using the pure JavaScript Jimp library. A Blob Trigger is used to detect incoming files, and a Blob Output binding is used to write the scaled image.

function.json

{
  "bindings": [
    {
      "name": "inputBlob",
      "type": "blobTrigger",
      "dataType": "binary",
      "direction": "in",
      "path": "images-in/{name}",
      "connection": "function821251a1b074_STORAGE"
    },
    {
      "type": "blob",
      "name": "outputBlob",
      "path": "images-out/{name}",
      "connection": "function821251a1b074_STORAGE",
      "direction": "out"
    }
  ],
  "disabled": false
}

index.js

var Jimp = require("jimp");

module.exports = function(context, inputBlob) {
    Jimp.read(inputBlob, function(err, image) {
        image.scale(0.5);
        image.getBuffer(Jimp.AUTO, function(error, imageData) {
            context.log('Node.JS blob trigger function resized ' + context.bindingData.name + ' to ' + image.bitmap.width + 'x' + image.bitmap.height);
            context.bindings.outputBlob = imageData;
            context.done();
        });
    });
};