To upgrade the efficiency of image diagnosis by making the condition of a subject visible at a part deteriorated in quality of spectral image.
An ordinary observation image P captured by an endoscope 20 is acquired, and a matrix mathematical operation is applied to this image P to produce a spectral assumption image SP. The ordinary observation image P is divided into a plurality of block regions, and the brightness YR is detected for each block region BR. It is determined whether the brightness YR of each block region BR is within the range of prescribed threshold values (Y1ref≤YR≤Y2ref). A composite image CP is produced by using the image data of spectral assumption image SP for the divided regions BR whose brightness is within the range of prescribed threshold values, and those of the ordinary observation image P for the regions BR with brightness out of the prescribed threshold values.
Go Sakuma
Daiki Motozawa