double fr2x(double d, double m)
A double floating-point value giving the cartesian x coordinate for the pixel whose polar coordinates are [d,m].
Pixels are usually addressed by their cartesian coordinates [x,y], but FilterMeister also allows the use of polar coordinates, and provides a set of functions for conversion between the two systems. Polar coordinates are expressed as [d,m], where 'd' represents the 'direction' to the pixel from the image's center point, and 'm' is the 'magnitude' of the distance from the center. The fr2x() function takes a pair of polar coordinates as arguments, and returns the cartesian x coordinate of the corresponding pixel.