1. An image analysis method comprising: acquiring an image of at least one frame that comprises pixels; setting at least one analytic region for the image of at least one frame; extracting data on the pixel corresponding to each analytic region; setting time intervals for data pairs for use in correlation calculations; performing a correlation calculation for each of the time intervals by use of the extracted data; and performing a fitting for each of the correlation calculation results, wherein the acquiring the image of the at least one frame acquires images of frames, and the setting the at least one analytic region sets analytic regions for the image of each frame, the analytic regions being the same regions in the image of each frame, respectively, wherein the performing the correlation calculation includes performing the correlation calculation by use of pairs of data on the pixels in different analytic regions in the images of different frames.