Patent ID: 7127064

Claim:
An image processing method for processing a gray scale conversion of image data obtained by radiation photograph, comprising: a first calculation step of calculating a parameter for determining a gray scale conversion processing method from a photographic subject area of the image data, as a first feature amount; a second calculation step of calculating a parameter for determining the gray scale conversion processing method from a predetermined area of the image data, as a second feature amount; a selection step of selecting, based on a value of the first feature amount and a value of the second feature amount, either the value of the first feature amount or the value of the second feature amount; and a processing step of performing the gray scale conversion process on the image data, based on the selected value, wherein calculation accuracy using the first feature amount is higher than that obtained using the second feature amount, and a success frequency of calculation using the first feature amount is lower than that obtained using the second feature amount.