PURPOSE: To reduce the scale of the system in the case of selecting a focus area and of direction discrimination of moving direction of a lens at focus operation start by implementing fuzzy inference in which various decisive factors such as focal distance are used as input variables and a focal direction or a selected area is a conclusion section.
CONSTITUTION: The fuzzy inference used for direction discrimination processing uses an evaluation value V 1 , variables ΔV 1 , ΔV 2 , a change Δr 1 and a contrast ΔE 1 as input variables and uses a conclusion section having a value of 0-1. When the conclusion value is larger, the direction of focus is taken as the current progressing direction of a lens and when smaller, the direction is taken reverse. In the area selection processing, the fuzzy inference uses a focus evaluation value V 1 , a contrast ΔE 1 , a focal distance Z and a mean brightness IRS as input variables and the conclusion section takes a value of 0-1. When the value is smaller, a 1st area A is used and when larger, a 2nd area B is used. Thus, the decision having lots of factors to be checked is implemented in the inference based on a few rules decided experimentally in advance.