Image noise reduction method and device

Abstract

The present invention relates to an image noise reduction method and apparatus to be preferably used to digitize and process, for example, an image signal. Therefore, in the case of the present invention, level values a to h of peripheral pixels and the level value o of a watched pixel are respectively input to, for example, eight comparators 11 and the value "1" is output when absolute values of differences between the level values are smaller than the value of a reference level &thetas;. Moreover, peripheral pixels at point-symmetric positions about the watched pixel o are combined and signals output from the comparators 11 are supplied to four AND circuits 12 in accordance with combinations. Then, signals output from the AND circuits 12 are supplied to eight AND gates 13 in accordance with each combination and level values a to h of corresponding peripheral pixels are output to output ports 3 through the AND gates 13 when signals output from the AND circuits 12 respectively have the value "1". Moreover, signals output from the AND circuits 12 are supplied to an adder 14, the addition output is doubled by a multiplier 15, and the value "1" is added to the multiplication value and output to an output port 4. Thereby, it is possible to perform the averaging operation by using only pixels in which pixels at point-symmetric positions about, for example, a watched pixel are combined and both are selected and thereby, it is possible to solve the problem that an averaged signal phase is deviated from an original position.

Description

technical field [0001] The present invention relates to a method and apparatus for reducing image noise, eg preferably for processing digitized image signals. In particular, the present invention relates to a method and apparatus for reducing image noise for solving troubles when a so-called ε-filter is used to reduce the noise component of an image signal. Background technique [0002] For example, in order to reduce noise components contained in image signals, various methods have been proposed so far. Specifically, one of the simplest methods with a large noise reduction effect is a method of using a low-pass filter (hereinafter, replaced by LPF). The LPF is a device used to transmit only signals with frequency components lower than a reference. That is to say, if a signal with a frequency change is input to the LPF, and the amplitude of the output signal is observed, a characteristic is obtained, that is, the level of the high-frequency component is relatively low. ...

AI Technical Summary

Problems solved by technology

However, when the absolute value of the difference between the intermediate level and the levels of the pixels before and after the edge is close to the reference level θ, due to the slight fluctuation of the intermediate level, the direction is reversed, and the edge may be irregular, as shown in Figure 8B

Images