Moire eliminating filter and image processing method and apparatus using the filter

Abstract

Stripe patterns caused by grids having different pitches can be reduced when image data obtained by reading images photographed by using the grids are reproduced. A radiation image is read from a stimulable phosphon sheet on which the radiation image has been recorded by photographing using a grid of 3.4 lines/MM. Filtering processing by filtering means is carried out on digital image data obtained by the reading. The coefficients of a filter used in the filtering processing are −1, −1, 4, −3, −14, 0, 43, 68, 43, 0, −14, −3, 4, 1, −1. This filter is to reduce a response of a spacial frequency equal to or more than 3.3 cycles/mm to equal to or less than 5%, preferably to equal to or less than 2%. In processed image data obtained through filtering processing using such a filter, a response of 3.4 cycle/mm or 4.0 cycle/mm frequency corresponding to the grid of 3.4 lines/mm or 4.0 lines/mm is reduced, and an image having a suppressed stripe pattern caused by the grid can be obtained by reproduction of the processed image data.

Dependencies are inferred from the claim text.