JPS61128680A - Image data noise removing device - Google Patents

Abstract

PURPOSE:To remove an impulse noise by outputting an output data of an intermediate value selecting circuit as it is when an output of the intermediate value selecting circuit coincides with a data of a center position of an operating area and outputting an average value of an average value calculating circuit when they do not coincide with each other. CONSTITUTION:An unit data delay circuit 1 and an unit line delay circuit 2 extract an operation area of 3X3. The data in the extracted operating area is all except for a data e at a center position of an operating area inputted to an average value calculating circuit 3 and an extremum detecting circuit 4. A maximum value k and a minimum value l detected in the circuit 4 are inputted to an intermediate value selecting circuit 5 together with the data e, the intermediate value is selected and a signal p is obtained. The signal p is inputted together with an intermediate value j of the output of the data e and of the circuit 3 to a data selecting circuit 6. If the data e is larger or smaller than any other data in all the operating areas, it is judged that the data is disturbed by an impulse noise and it is replaced by an average value of other data in other operating area and in another cases, the data is not receive any change.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the technical field of image processing of image data replaced with electrical signals, and particularly relates to a technique for removing impulsive noise generated in image data. [Technology] Conventionally, a device using a median filter has generally been used as a device for removing impulsive noise contained in this type of image data. FIG. 2 shows a general configuration example of a median filter having a 3×3 operation area. In FIG. 2, it is assumed that image data is sequentially sent to the input signal i in a scanning sequence as shown in FIG. Second
In the figure, 1 is a unit data delay circuit, and 2 is a unit row delay circuit, each of which holds the previous data and the data of the previous row.The image data i' in Fig. 3 is applied to the input signal i. In this case, the input data a, b,
..., i is a', b', ... in Fig. 3.

i', and the operation region has been extracted.0 The intermediate value selection circuit 5 arranges the input signals in order of magnitude and outputs the middle value (intermediate value, the fifth largest value in the case of Fig. 2). An image data noise removal device using a median filter uses this output data to replace the central position data et'' of the operation area.

[Problem that the invention seeks to solve]

However, although impulsive noise is certainly effectively removed by an image data noise removal device using a median filter, information other than noise, especially information regarding the edges of objects present in the image, is also changed. The drawback is that the intermediate value selection circuit can be easily stored.
The disadvantage of the former method is that it is difficult to realize with a hardware configuration.The disadvantage of the former method is that when a 3×3 median filter is applied to the image data shown in FIG. 4, which does not contain any noise, the image shown in FIG. It can be easily inferred from the fact that it is changed as follows.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image data noise removal device that eliminates the above two drawbacks while maintaining the impulsive noise removal effect.

[Means for solving problems]

The image data noise removal device according to the present invention has a relatively small m x
A data extraction circuit that continuously extracts n data in the operation area over the entire screen, and an average of m x n -1 pieces of data extracted by the extraction circuit, excluding data at the center position of the operation area. An average value calculation circuit that calculates the value, an extreme value detection circuit that detects the maximum value and minimum value from among the m x n -1 data, and the detected maximum value and minimum value and the operation area center position data. An intermediate value selection circuit that selects an intermediate value from among three pieces of data; furthermore, when the output of the intermediate value selection circuit and the operation area center position data match, the output data of the intermediate value selection circuit is output as is; when they do not match, the output data of the intermediate value selection circuit is output as is; has a data selection circuit that outputs the average value determined by the average value calculation circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

The unit data delay circuit 1 and the unit row delay circuit 2 extract a 3×3 operation area as described in the description of the conventional embodiment. All of the extracted data within the operation area, except for data e at the center position of the operation area, are input to the average value calculation circuit 3 and the extreme value detection circuit 4. The maximum value and minimum value t detected by the extreme value detection circuit 4 are input to the intermediate value selection circuit 5 together with the operation area center position data e, and the intermediate value is selected and becomes the signal p.

Here, it is easy to understand that if the data e is not disturbed by impulsive noise, p=e, and if it is disturbed, then p=e. The output p of the intermediate value selection circuit 5 is inputted to the data selection circuit 6 together with the data e and the average value j which is the output data of the average value calculation circuit 3. If p=e, the output signal q is q=p(= e) is determined, and if pie, q=j is determined.

That is, in the embodiment of the present invention, if the data at the center position of the operation area is larger or smaller than any of the other data in the operation area, that data is determined to be disturbed by impulsive noise. Replaced by the average value of all other operating area data,
In other cases, the operation area center position data will not be changed at all.

〔Effect of the invention〕

As explained above, by sequentially defining the output signal q' obtained from the configuration shown in FIG. 1 as new image data, information regarding the edge of the object that originally exists in the image is lost. There is an advantage that an image data noise removal device that effectively removes only impulsive noise can be realized with relatively simple hardware.

Regarding the effect of reducing the hardware scale, compared to the conventional embodiment shown in FIG. 2, which requires an intermediate value selection circuit that arranges m x n input data in order of size.
In FIG. 1 according to the present invention, an intermediate value selection circuit that always handles three input data irrespective of the values of m and n is sufficient;
In the embodiment shown in FIG. 1, the average value calculation circuit, extreme value detection circuit, and data selection circuit required for the new nine can be realized with considerably small-scale hardware, so the reduction effect is obvious.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an image data noise removal device according to the present invention, and FIG. 2 is a block diagram showing an embodiment of an image data noise removal device using a conventionally common median filter. FIG. 3 is a diagram showing the scanning sequence of image data, which is a prerequisite for showing the embodiments of FIGS. 1 and 2. FIG. 4 and FIG. This is a diagram to show the defects, and is a diagram showing image data before and after processing, respectively. 0 1... Unit data delay circuit, 2... Unit row delay circuit, 3... ...Average value calculation circuit, 4...
. . . Extreme value detection circuit, 5 . . . Intermediate value selection circuit, 6 . . . Data selection circuit. Agent: Patent attorney Shin-cho Uchihara (1 piece) ---$21

Claims (1)

[Claims] A data extraction circuit that continuously extracts data within a relatively small m×n operation area over the entire screen from an array of image data that has a two-dimensional spread; An average value calculation circuit for m×n−1 data excluding data at the center position of the area, and an extreme value detection circuit for detecting the maximum value and minimum value from among the m×n−1 data, and detection An intermediate value selection circuit selects an intermediate value from among the three data of the maximum value and minimum value and the operation area center position data, and furthermore, when the output of the intermediate value selection circuit and the operation area center position data match, An image data noise removal device comprising a data selection circuit that outputs the output data of the intermediate value selection circuit as is, and outputs the average value obtained by the average value calculation circuit when the data do not match.