Create a custom filter out of list of step definitions. A filter is a function wich returns new color for a given one.

Each step can be one of:

• a function which takes color and returs new color
• a vector with an operator name as a keyword and arguments
  • one of the: :sepia, :contrast, :exposure, :brightness, :grayscale, :hue-rotate, :saturation, :tint - with an amount as the argument (see below)
  • :temperature with temperature in Kelvins and amount (0.0-1.0)
  • :matrix - feColorMatrix definition, see here
  • :blend for blending two colors, parameters are blednding operator and a color (see below)

Bleding operators are defined in clojure2d.color.blend/blends-list plus :hue, :saturation, :luminocity and :color which copies one/two channels between colors in HSB color space. see here.

Note: CSS brightness is defined as :exposure which multiplies channels by given amount. :brightness changes channels by adding a percentage of the original value.

Example: to construct moon filter, our definition will look like below:

(custom-filter [:blend :softlight (c/gray 0xa0)] [:blend :lighten (c/gray 0x38)] [:grayscale 1.0] [:contrast 1.1] [:exposure 1.1])