getColor method
Create a Color object with the format and number of channels of the image.
Implementation
@override
Color getColor(num r, num g, num b, [num? a]) => a == null
? ColorUint4.rgb(r.toInt(), g.toInt(), b.toInt())
: ColorUint4.rgba(r.toInt(), g.toInt(), b.toInt(), a.toInt());