IMAGE PROCESSING DEVICE AND METHOD, AND IMAGE PROCESSING PROGRAM

摘要

An NR coefficient (Kf) is calculated on the basis of a representative value (Pm) of a pixel of interest and a low-pass filtered value (La-Ld) nearest to the representative value (Pm) of the pixel of interest among a plurality of low-pass filtered values filtered one-dimensionally in different directions in an input image, and the pixel value of the pixel of interest and a value output by a two-dimensional low-pass filter (25) are weighted by the NR coefficient (Kf) and added (36). The representative value of the pixel of interest may be for example, a median value obtained by filtering the current frame and a past frame in the time axis direction. The image processing device reduces noise without lowering resolution.

主权项

1. An image processing device for receiving a moving picture including a time sequence of frames, the image processing device comprising:
a plurality of one-dimensional low-pass filters calculating respective low-pass filtered values using a pixel of interest and pixels aligned in different one-dimensional directions with respect to the pixel of interest, in a processing window including a plurality of pixels centered on the pixel of interest, in a frame of interest; a peripheral low-pass filter outputting, as a peripheral low-pass filtered value, a low-pass filtered value obtained using the pixel of interest and neighboring pixels thereof in the processing window; a representative value calculator for performing filtering in a time axis direction, based on a pixel value of the pixel of interest in the frame of interest and a pixel value of a pixel in a position corresponding to the pixel of interest in at least one frame other than the frame of interest, to obtain a representative value for the pixel of interest; a noise level detector for calculating absolute values of differences between the representative value and each of the one-dimensionally low-pass filtered values and outputting, as a noise level of the pixel of interest, a minimum value among those of the calculated absolute differences that satisfy a predetermined condition; an NR coefficient generator for receiving the noise level and generating a noise reduction coefficient corresponding to the noise level according to a predetermined input-output characteristic; and an NR processor for using the noise reduction coefficient to take a weighted sum of the pixel value of the pixel of interest and the peripheral low-pass filtered value.