For the purpose of accurately calculating the average value M of original complex
observed signals S from an absolute-value image produced by the complex observed
signals S, in Step A1, the average value Ma of pixel values |S| of the absolute-value
image in a local region is calculated by:
Ma=|S|/k,
wherein the number of pixels in the local region is represented as k.
In Step A2, the average value M of the original complex observed signals S is
calculated by the following equation:
M=-1 (Ma/),
wherein -1 (Ma/) is an inverse function of the function
Ma/=(M/) represented as:
Ma/={|M/+(X+iY)|exp{-(X2+Y2)/2}/2}dX dY.
