Image encoding in Node JS

11 Apr 2019

This article is work in progress!

While programming on a side project, I had to deal with images in a node application. My application is using Express, Amazon Rekognition as well as Pouchdb.

I was dealing with different sources & targets:

• A user uploads a picture
• I read a picture from file, be it in JPEG or PNG format
• I send a picture to AWS
• I store a picture in my pouchDB

While browsing the different sources, I encountered various formats on how images can be handled in node:

• As buffer containing binary data
• As string conatining Base64 encoded data, starting with something like data:image/jpeg;base64, (or with png)
• As string containing base64 encoded data without the special beginning

These are the different operations I am doing and what they provide as output:

• Reading a file from disk with fs: return a Bufferwith binary data

These are the sources and targets in/from which image data is transferred in my example:

Reading

Helpful stuff I found about the topics:

• How do I convert an image to a base64-encoded data URL in sails.js or generally in the servers side JavaScript? StackOverflow
• NodeJS base64 image encoding/decoding not quite working, StackOverflow
• Inkjet, JPEG-image decoding, encoding & EXIF reading library for a browser and node.js, Github