Function darken_hsl 

pub fn darken_hsl(img: &mut PhotonImage, level: f32)

Darken the image by a specified amount in the HSL colour space.

Arguments

• img - A PhotonImage.
• level - Float value from 0 to 1 representing the level to which to darken the image by. The level must be from 0 to 1 in floating-point, f32 format. Darkening by 80% would be represented by a level of 0.8

Example

// For example to darken an image by 10% in the HSL colour space:
use photon_rs::colour_spaces::darken_hsl;
use photon_rs::native::open_image;

// Open the image. A PhotonImage is returned.
let mut img = open_image("img.jpg").expect("File should open");
darken_hsl(&mut img, 0.1_f32);