brighten
========

Goal:
-----
Increases or decreases the brightness of the supplied image.

Syntax:
-------
`brighten <int>`

where <int> means: any 32 bit signed integer is required as parameter input.

A positive value for <int> means the brightness will be increased, and a negative value for <int> means the brightness will be decreased.

Usage example:
--------------
`sic input.png output.png --apply-operations "brighten 10;"`
or
`sic input.png output.png --apply-operations "brighten -10;"`

See also:
---------
https://docs.rs/image/0.19.0/image/imageops/colorops/fn.brighten.html