alter

Alter is a Node service that provides real-time image manipulation for responsive images using URL.

Comparison

Method	Pros	Cons
3rd Party	Very easy and simple to implement	- Lots of features which are not required
		- Bounded to 3rd party for any new requirement
		- Conversion of existing URLs
Pre-Compute	Easy to implement	- Too many moving parts in background
		- Too many files to stores
		- Maintaining a script for back-filling
Real Time	Easy and simple to implement	- High latencies
		- Heavy core machines

Architecture

The proposed architecture is to put it behind a CDN for better performance.

Transformations

The following transformations are available -

• Resize
  • Change either width or height will keep aspect ratio intact
  • To resize image provide both height and width. Default crop is center.
• Image format
  • WebP
  • JPEG
• Blur
• Thumbnail