Photoshop levels tools / hue - saturation implementation

MrSilverstone

Hi everyone, I would like to implement the levels and hue saturation tool from photoshop :

Unfortunately, I don't know the math behind this tools. Do you have any leads wich could help me? My goal is to turn a picture like this :

Into this :

Thanks for you help!

colouredmirrorball

Processing has the HSB color mode implemented.

https://processing.org/reference/colorMode_.html

First set the color mode to HSB, then loop over all the pixels (https://processing.org/reference/pixels.html), retrieve their hue/saturation values and shift them the way you want.

MrSilverstone

Thanks for your answer, I just discovered that I had to "shift" all the values of the hue circle by the amount I wanted.