To provide a processing method of an image data and a program in order to obtain an evaluation scales where the image data is digitized.

The processing method of the image data of an embodiment comprises: acquiring an inspection target pixel data from the inspection target; dividing the inspection target pixel data into m×n rectangular region data (m and n are natural numbers); obtaining inspection target image data expressing the inspection target pixel data in respective divided rectangular region data with numerical values; obtaining a sum of the inspection target image data in a row direction and a sum of the inspection target image data in a column direction respectively to compress respective sums into m+n inspection target compressed data; obtaining a proportional constant of zero point proportional dynamic characteristics and SN ratio using m+n sample data so that m+n reference compressed data obtained by compressing data for a reference image are set as a signal factor.