Optical filtering device and method for using the same

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

• receiving said initial input image data array in a filter processing device;
• generating a plurality of fundamental operators within at least one fundamental operator series;
• convolving said initial input image data array with one of said fundamental operators in said filer processing device to produce an initial output image data array;
• selectively inputting said initial output data array back into said filter processing device to be convolved with a different one of said fundamental operators by detecting at least one selected condition of said initial output image data array, and determining whether each said selected condition of said output image array satisfies a respective reference condition
• generating at least one successive output image data array with said filter processing device and selectively and sequentially sending each successive output image data array, as successive input data arrays, back to said filter processing device, whenever each reference condition is not satisfied by each of said successive output image data arrays;
• convolving a different fundamental operator from said fundamental operator series with a successive input image data array each time that a successive output image data array is sent back to said filter processing device;
• outputting one of said output image data arrays only when each reference condition is satisfied;
• and
• controlling an automatic focus mechanism of a camera with said signal.

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

• receiving said initial input image data array in a filter processing device;
• generating a plurality of fundamental operators within at least one fundamental operator series;
• convolving said initial input image data array with one of said fundamental operators in said filter processing device to produce an initial output image data array;
• selectively inputting said initial output image data array back into said filter processing device to be convolved with a different one of said fundamental operators wherein said fundamental operators are generated by generating an original fundamental operator based upon at least one of the following element functions:
• ##EQU6## where x=n+K(k), K(k) being zero or a function of a variable k and n being the position of image data which has been convolved, wherein all of the fundamental operators in said fundamental operator series are based upon said original fundamental operators, said fundamental operator series containing 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.sup.k)+U(n-2.sup.k)];
• or
• (b) a first order differential operator D.sup.(+) (n,k) defined as:
• D.sup.(+) (n,k)=(1/2) [U(n-2.sup.k)-U(n+2.sup.k)];
• or
• (c) a second order differential operator D"(n,k) defined as:
• D"(n,k)=(U(n)/2)-(1/4) [U(n+2.sup.k)+U(n-2.sup.k)]
• where k=0, 1, 2, 3 .

A filtering device for effecting a filtering process in a space domain of image data derived from an external visual image input means, said device being adapted to deliver control information to a controlled driving means, said filtering device comprising;

• means for generating an original fundamental operator;
• filter processing means for convolving an initial input image data array and successive input image data arrays with respective fundamental operators to produce respective output image data arrays;
• and
• means for sequentially convolving each input image data array by sequentially and selectively inputting successive output image data arrays from said filter processing means back into said filter processing means as said successive input image data arrays and by convolving each successive input image data array input back into said filter processing means with a different fundamental operator from said fundamental operator series, wherein said original fundamental operator is based upon at least one of the following element functions;
• ##EQU7## where x=n+K(k), K(k) being zero or a function of a variable k and n being the position of image data subjected to a filtering process, all fundamental operators in a single fundamental operator series being generated from said original fundamental operator, said original fundamental operator consisting of at least one of an integration operator I(n,k), a differential operator of the first order D.sup.(+) (n,k), a differential operator of the second order D"(n,k), with each of said integration and differential operators being defined below, respectively, as:
• I(n,k)=(U(n/2)+(1/4)(U(n+2.sup.k)+U(n-2.sup.k)), and
• D.sup.(+) (n,k)=(1/2)(U(n-2.sup.k)-U(n+2.sup.k)), and
• D"(n,k)=(U(n)/2)-(1/4)(U(n+2.sup.k)+U(n-2.sup.k))
• where k=0, 1, 2, 3.