An image processing device clips a plurality of partial images from an image, and calculates difference values of pixel values between a target pixel and surrounding pixels surrounding the target pixel in the partial images. Then, the image processing device decides parameter values corresponding to respective surrounding pixels based on identification information that identifies the partial image from among the plurality of the partial images and the difference values, and calculates a feature amount corresponding to the target pixel using the parameter value decided. Then, the image processing device obtains a feature amount of the partial images by calculating the feature amount with the above-described steps, using each pixel in the partial images as the target pixels.