Image boundary detection for a scanned image

Claim 3

A method as in claim 1 wherein in substep (a.1) for each scan row, the subset of pixels includes pixels located right of the current rightmost edge.

Claim 4

A method as in claim 1 wherein in substep (a.1.2.1) a first edge is included within any edge from a previous row which is continued by the first pixel when the first edge either includes a pixel directly above the first pixel or includes a pixel one pixel above and one pixel to the right of the first pixel.

Claim 5

A method as in claim 1 wherein step (b) includes the following substep: (b.1) for each scan row, performing the following substeps for a horizontal subset of pixels in the scan row: (b.1.1) detecting when a second pixel in the substep of pixels has a grey value which differs from a grey value of a pixel immediately above the second pixel by at least the first predetermined constant, and (b.1.2) when in substep (a.1), the second pixel in the substep of pixels has the grey value which differs from the grey value of the pixel immediately above the second pixel by at least the first predetermined constant, performing the followings substeps: (b.1.2.1) detecting a longest horizontal edge which includes the second pixel, and (b.1.2.2) when a total length of the longest horizontal edge exceeds the second predetermined constant, storing a y-coordinate of the second pixel as a current bottom edge.

Claim 6

A method as in claim 4 wherein substep (b.1.2.1) includes the following substeps: (b.1.2.1.1) detecting any edge from a right of the second pixel which is continued by the second pixel; (b.1.2.1.2) detecting any edge from a left of the second pixel which is continued by the second pixel; and (b.1.2.1.3) combining any edge from the right of the second pixel detected in substep (b.1.2.1.1) with any edge from the left of the second pixel detected in substep (b.1.2.1.2) to produce the longest horizontal edge.

Claim 7

A method as in claim 5 wherein substep (b.1.2.1.1) a first edge is included within any edge from the right of the second pixel which is continued by the second pixel when the first edge either includes a pixel directly to the right of the second pixel or includes a pixel one pixel above and one pixel to the right of the second pixel.

Claim 8

A method as in claim 5 wherein substep (b.1.2.1.2) a first edge is included within any edge from the left of the second pixel which is continued by the second pixel when the first edge either includes a pixel directly to the left of the second pixel or includes a pixel one pixel above and one pixel to the left of the second pixel.

Claim 11

A method as in claim 8 wherein substep (b.1.2.1) includes the following substeps: (b.1.2.1.1) detecting any edge from a right of the first pixel which is continued by the first pixel; (b.1.2.1.2) detecting any edge from a left of the first pixel which is continued by the first pixel; and (b.1.2.1.3) combining any edge from the right of the first pixel detected in substep (b.1.2.1.1) with any edge from the left of the first pixel detected in substep (b.1.2.1.2) to produce the longest horizontal edge.

Claim 12

A method as in claim 9 wherein substep (b.1.2.1.1) a first edge is included within any edge from the right of the first pixel which is continued by the first pixel when the first edge either includes a pixel directly to the right of the first pixel or includes a pixel one pixel above and one pixel to the right of the first pixel.

Claim 13

A method as in claim 9 wherein substep (b.1.2.1.2) a first edge is included within any edge from the left of the first pixel which is continued by the first pixel when the first edge either includes a pixel directly to the left of the first pixel or includes a pixel one pixel above and one pixel to the left of the first pixel.

Claim 16

A method as in claim 12, wherein in substep (a.1) the first predetermined constant is 7.

Claim 17

A method as in claim 12 wherein in step (a) for each scan row, the subset of pixels includes pixels located right of the current rightmost edge.

Claim 18

A method as in claim 12 additionally comprising the following step: (b) using the current rightmost edge as an x-coordinate of the vertical edge.

Claim 19

A method as in claim 12 wherein in substep (a.2.1) a first edge is included within any edge from a previous row which is continued by the first pixel when the first edge either includes a pixel directly above the first pixel or includes a pixel one pixel above and one pixel to the right of the first pixel.

Claim 22

A method as in claim 17 wherein substep (a.2.1) includes the following substeps: (a.2.1.1) detecting any edge from a right of the first pixel which is continued by the first pixel; (a.2.1.2) detecting any edge from a left of the first pixel which is continued by the first pixel; and (a.2.1.3) combining any edge from the right of the first pixel detected in substep (a.2.1.1) with any edge from the left of the first pixel detected in substep (a.2.1.2) to produce the longest horizontal edge.

Claim 23

A method as in claim 17 wherein substep (a.2.1.1) a first edge is included within any edge from the right of the first pixel which is continued by the first pixel when the first edge either includes a pixel directly to the right of the first pixel or includes a pixel one pixel above and one pixel to the right of the first pixel.

Claim 24

A method as in claim 17 additionally comprising the following step: (b) using the current bottom edge as a y-coordinate of the horizontal edge.

Claim 25

A processing system for determining in a matrix array having fixed minimum and maximum x coordinate values and fixed minimum and maximum y coordinate values a minimal rectangular boundary box within which a replica image of an original scanned document is defined, comprising: a processor having: a horizontal edge arrangement for determining a variable right edge x coordinate value for helping to define a bottom right corner of said boundary box; and a vertical edge arrangement for determining a variable bottom edge y coordinate value for further helping to define said bottom right corner of said boundary box, wherein said vertical edge arrangement includes: a portion of a buffer memory for temporarily storing image data indicative of the replica image, said image data being defined by a plurality of gray scale pixel values arranged in rows and columns to facilitate image processing purposes; a pixel processor for determining row by row and pixel by pixel whether the gray scale pixel value of a current pixel in a given row differs from the gray scale value of an adjacent pixel in the same row by at least a predetermined constant vertical value and for determining whether the current pixel in said given row extends a line segment having a given length exceeding another predetermined constant vertical value; and, a portion of a scratch memory for storing an x coordinate value of the right most pixel in said line segment extended by said current pixel when said line segment has a given length exceeding said another predetermined constant vertical value; wherein said x coordinate value of the right most pixel in said line segment being defined as said variable right edge x coordinate value when the current pixel is the last pixel in said image data.

Claim 26

A processing system for determining in a matrix array having fixed minimum and maximum x coordinate values and fixed minimum and maximum y coordinate values a minimal rectangular boundary box within which a replica image of an original scanned document is defined, comprising: a processor having: a horizontal edge arrangement for determining a variable right edge x coordinate value for helping to define a bottom right corner of said boundary box; and a vertical edge arrangement for determining a variable bottom edge y coordinate value for further helping to define said bottom right corner of said boundary box, wherein said vertical edge arrangement includes: a portion of a buffer memory for temporarily storing image data indicative of the replica image, said image data being defined by a plurality of gray scale pixel values arranged in rows and columns to facilitate image processing purposes; a pixel processor for determining row by row and pixel by pixel whether the gray scale pixel value of a current pixel in a given row differs from the gray scale value of an adjacent pixel in the same row by at least a predetermined constant vertical value and for determining whether the current pixel in said given row extends a line segment having a given length exceeding another predetermined constant vertical value; and, a portion of a scratch memory for storing an x coordinate value of the right most pixel in said line segment extended by said current pixel when said line segment has a given length exceeding said another predetermined constant vertical value; wherein said x coordinate value of the right most pixel in said line segment being defined as said variable right edge x coordinate value when the current pixel is the last pixel in said image data.

Claim 27

A processing system according to claim 21, wherein said horizontal edge arrangement includes: another portion of said buffer memory for temporarily storing image data indicative of the replica image; said pixel processor for further determining row by row and pixel by pixel whether the gray scale pixel value of said current pixel in said given row differs from the gray scale value of an adjacent pixel immediately above in an adjacent row not defining a boundary edge with a y coordinate value of zero by at least a predetermined constant horizontal value and for determining whether the current pixel in said given row extends a horizontal line segment having a given length exceeding another predetermined constant horizontal value; another portion of said scratch memory for storing a y coordinate value of the current pixel when said horizontal line segment has a length exceeding said another predetermine constant horizontal value; and said y coordinate value of the current pixel being defined as said variable bottom edge y coordinate value when the current pixel is the last pixel in said image data.

Claim 28

A processing system according to claim 22, further comprising: a boundary coordinate defining arrangement responsive to said horizontal edge arrangement and said vertical edge arrangement for defining top left corner coordinate values, top right corner coordinate values, bottom left corner coordinate values and bottom right corner coordinate values of the boundary box; said top left corner having x and y coordinate values defined respectively by 0 and 0 respectively; said top right corner having x and y coordinate values defined respectively by 0 and a determined variable right edge x coordinate value; said bottom left corner having x and y coordinate values defined respectively by 0 and a determined variable bottom edge y coordinate value; and said bottom right corner having x and y coordinate values defined respectively by said determined variable right edge x coordinate value and said determined variable bottom edge y coordinate value.

Claim 31

A method according to claim 24, further comprising: defining a top left corner location of the boundary box in said matrix array, said top left corner having x and y coordinate values defined respectively by 0 and 0 respectively; determining a top right corner location of the boundary box in said matrix array, said top right corner having x and y coordinate values defined respectively by 0 and a determined variable right edge x coordinate value; determining a bottom left corner location of the boundary box in said matrix array, said bottom left corner having x and y coordinate values defined respectively by 0 and a determined variable bottom edge y coordinate value; and determining a bottom right corner location of the boundary box in said matrix array, said bottom right corner having x and y coordinate values defined respectively by said determined variable night edge x coordinate value and said determined variable bottom edge y coordinate value.