When a displacement between a reference flame of a plurality of images acquired by continuous image pickup and a target flame is less than a first threshold indicating that such a flame is not likely to be affected by occlusion, smoothing is performed on an object area through a morphological operation with a normal process amount. At least one of these major surfaces bears a functional coating and has a peripheral region that is substantially free of the functional coating. Eighteen first sense amplifiers 1-18) can be connected to the first memory cell array and eighteen second sense amplifiers 1-18) can be connected to the second memory cell array.