About the Encoder property

The Encoder property contains the indications about the quality compromise to accept when encoding image to final format.

This object allows specifying two properties: a quality measure and a lower threshold for the quality measure.

Admisible values for quality measure are:

- `default`: Let's our platform select a default measure
- `ssim`: Structural Similarity Index. 
- `fsim-c`: Phase congruency image similarity measure.
- `asymmetric-fsym-c`: A modification of fsim-c that gives less
   weight to compression artifacts in uniform-color backgrounds.
- `perceptual-sc`: A simple neural-network approach
   that tries to mimic the human capability to notice image
   compression artifacts. 

Admisible values for the quality measure is a number between 0.25 and 1.00. The The encoder will try to produce the smallest image whose quality (as defined by the quality measure) is above this quality threshold.