Optical filtering device and method for using the same

• US 5,128,706 A
• Filed: 02/25/1991
• Issued: 07/07/1992
• Est. Priority Date: 03/23/1987
• Status: Expired due to Term

• Current Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Original Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Inventors: Shindo, Osamu, Toji, Shigeo, Suzuki, Noboru
• Primary Examiner(s): PERKEY, WILLIAM B
• Application Number:
  US07/659,486
• Time in Patent Office: 498 Days
• Field of Search: 354/402, 354/406, 354/407, 354/408, 250/201.2, 364/572, 364/604, 364/728.01, 364/728.02, 364/724.12, 364/819, 364/825, 382/42, 382/49
• US Class Current: 396/101
• CPC Class Codes: G02B 7/365 by analysis of the spatial frequency components of the image
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing

Abstract

A filtering device for carrying out a filtering process in a space domain of image data derived from an external visual image input means and then delivering control information to a controlled driving device with the filtering device containing fundamental operator generation device for generating fundamental operators within the same fundamental operator series, and a filtering processing device for carrying out a convolution of a fundamental operator with an image data array and conducting a sequential series of such convolutions with varying input data based upon data detected at the output of the filter processing, so that the sequential convolution attains an effect equivalent to that attained by the direct convolution of the initial image data array with an expanded operator.

Claims

1. A filtering device for effecting a filtering process in a space-domain of initial image data derived from an external visual image input source, said filtering device comprising:

(a) means for generating fundamental operators within at least one predetermined sequence of fundamental operator series;

(b) means for convolving an initial input image data array and successive input image data arrays with respective fundamental operators in a predetermined sequence to produce successive output image data arrays representative of said convolved input image data arrays;

(c) means for determining whether each successive output image data array satisfies at least one predetermined condition; and

(d) means for selectively sending one of said output image data arrays to a post-filter processing device only when each predetermined condition is satisfied by said one output image data array, wherein said generating means comprises means for generating an original fundamental operator based upon at least one of the following element functions;

##EQU4## where x=n+K(k);

where, K(k) is zero or a function of a variable k; and

wherein n is the position of image data subjected to a filtering process, wherein all fundamental operators in a single fundamental operator series are to be generated from said original fundamental operator.

2. A filtering device in accordance with claim 1 wherein each of said fundamental operator series consists of a combination of said element functions, each of said element functions having a coefficient which is a multiple of two.

3. A filtering device for effecting a filtering process in a space-domain of initial image data derived from an external visual image input source, said filtering device comprising:

(a) means for generating fundamental operators within at least one predetermined sequence of fundamental operator series;

(b) means for convolving an initial input image data array and successive input image data arrays with respective fundamental operators in a predetermined sequence to produce successive output image data arrays representative of said convolved input image data arrays;

(c) means for determining whether each successive output image data array satisfies at least one predetermined condition; and

(d) means for selectively sending one of said output image data arrays to a post-filter processing device only when each predetermined condition is satisfied by said one output image data array, wherein said convolving means comprises means for sequentially convolving individual fundamental operators from said series of fundamental operators with said successive input image data arrays, said fundamental operators comprising expanded operators which affect high-frequency components of said input image data arrays.

4. A filtering device in accordance with claim 3, wherein said fundamental operators further comprises expanded operators which affect low frequency components contained in said input image data arrays.

5. A filtering device in accordance with claim 4, wherein said generating means include means for generating said fundamental operators in a single fundamental operator series by selecting a variable (k) of an original fundamental operator as a variable integer.

6. A filtering device for effecting a filtering process in a space-domain of initial image data derived from an external visual image input source, said filtering device comprising:

(a) means for generating fundamental operators within at least one predetermined sequence of fundamental operator series;

(b) means for convolving an initial input image data array and successive input image data arrays with respective fundamental operators in a predetermined sequence to produce successive output image data arrays representative of said convolved input image data arrays;

(c) means for determining whether each successive output image data array satisfies at least one predetermined condition; and

(d) means for selectively sending one of said output image data arrays to a post-filter processing device only when each predetermined condition is satisfied by said one output image data array, wherein said at least one fundamental operator series comprises a single fundamental operator series.

7. A method for effecting a filtering process in a space-domain of an initial image data array derived from an external visual input source, comprising the steps of:

(a) receiving the initial input image data array in a filter processing device;

(b) generating fundamental operators within at least one fundamental operator series;

(c) convolving the initial input image data array and successive input image data arrays with respective fundamental operators in a filter processing device to produce successive output image data arrays which are representative of the convolved input image data arrays;

(d) determining whether each successive output image data array satisfies at least one predetermined condition; and

(e) selectively sending one of the output image data arrays to a post-filter processing device only when each predetermined condition is satisfied by the output image data array.

8. A method in accordance with claim 7, wherein the fundamental operators are generated in a single fundamental operator series.

9. A method in accordance with claim 7, further comprising the step of generating at least one successive output image data array with the filter processing device and selectively and sequentially sending each successive output image data array, as successive input image data arrays, back to the filter processing device, whenever each reference condition is not satisfied by each of the successive output image data arrays.

10. A method in accordance with claim 9, further comprising the step of convolving a different fundamental operator from the fundamental operator series with a successive input image data array each time that a successive output image data array is sent back to the filter processing device.

11. A method in accordance with claim 10, wherein the initial input image data is received by a filtering device and is placed in a memory storage region, the method further comprising the step of setting a variable integer (k) equal to 0, selecting an original fundamental operator from a plurality of original fundamental operators stored in a memory storage region of a fundamental operator generation device, and thereafter generating one fundamental operator to be convolved with the initial input image data array.

12. A method in accordance with claim 11, further comprising the step of sending a first signal from a main memory storage to effect the generation of a variable integer (k) having a predetermined value when the reference condition is not satisfied, and sending a second signal from a comparator to a fundamental operator generation device to select an original fundamental operator from a memory storage region in the fundamental operator generation device.

13. A method in accordance with claim 12, further comprising the step of sending the variable integer (k) to the fundamental operator generation device to generate a new fundamental operator.

14. A method in accordance with claim 7, wherein a control signal is generated by the post-filter processing device.

15. A method in accordance with claim 14, further comprising the step of driving a motor with the control signal.

16. A method in accordance with claim 7, wherein the fundamental operators are generated by generating an original fundamental operator based upon at least one of the following element functions:

##EQU5## where x=n+K(k), wherein K(k) is zero or a function of a variable k, and n is the position of image data which has been convolved, wherein all of the fundamental operators in the fundamental operator series are based upon the original fundamental operators.

17. A method in accordance with claim 16, wherein the fundamental operator series contains at least one of the following:

(a) an integration operator I(n,k) defined as;

I(n,k)=(U(n/2)+(1/4)[U(n+2^k)+U(n-2^k)];

or

(b) a first order differential operator D.sup.(+) (n,k) defined as;

D.sup.(+) (n,k)=(1/2) [U(n-2^K)-U(n+2^k)];

or

(c) a second order differential operator D"(n,k) defined as;

D"(n,k)=U(n)/2)-(1/4) [U(n+2^k)+U(n-2^k)]

where k=0, 1, 2, 3 . . .

18. A method in accordance with claim 11, wherein said original fundamental operator is selected by an external signal from a keyboard.