Film thickness measurement system, film thickness measurement method, and storage medium

A film thickness measurement system acquires spectroscopic data relating to first positions on the surfaces of N first substrates on which first films having different film thicknesses are formed, and acquires the film thickness of the first films at the first position for each of the N first substrates. First image data is acquired by imaging the surfaces of N second substrates on which second films having different film thicknesses are formed by an imaging unit, and first color information in a plurality of first sub-regions in a first region is acquired for each of the N second substrates. The correlation between the film thickness of the second fils in the first region and the first color information for each of the plurality of first sub-regions in the first region is acquired, and the surface of the third substrate on which the third film is formed is imaged using the imaging unit to acquire second image data. Second color information is acquired for each of the plurality of second sub-regions, and the