JP2004088499A5

JP2004088499A5 -

Info

Publication number: JP2004088499A5
Application number: JP2002247643A
Authority: JP
Filing date: 2002-08-27
Publication date: 2005-10-06
Anticipated expiration: 2022-08-27

Claims

In an image distortion correction apparatus that corrects distortion of a scanned image obtained by reading a book document placed on a contact glass with the page binding portion parallel to the main scanning direction of image reading by an image reading unit,
A main scanning direction distortion correction rate calculating means for calculating a distortion correction rate in the main scanning direction based on the shape of a page outer shape, ruled lines, character lines of the scanned image or an image center line penetrating the scanned image in the sub-scanning direction;
Main-scanning direction distortion correcting means for expanding the scan image in the main scanning direction using the distortion correction ratio calculated by the distortion correction rate calculating means to correct distortion of the scan image;
Sub-scanning direction distortion correction rate calculation that extracts a character circumscribing rectangle from the corrected image corrected by the main scanning direction distortion correcting unit and calculates a distortion correction rate in the sub-scanning direction based on the extracted shape of the character circumscribing rectangle Means,
A sub-scanning direction distortion correction unit that extends the correction image in the sub-scanning direction using the distortion correction rate calculated by the sub-scanning direction distortion correction rate calculation unit, and corrects the distortion of the correction image;
An image distortion correction apparatus comprising:

The main-scanning-direction distortion correction rate calculating means includes a reference line that is a page outline, a ruled line, or a character line located in the vicinity of the upper side or the lower side in the main scanning direction of the scanned image, and a side opposite to the side on the reference line side A virtual page outline that is a virtual page outline calculated based on a page outline, ruled line, character line, or reference line that is the shape of the image center line that penetrates the scanned image in the sub-scanning direction. The image distortion correction apparatus according to claim 1, wherein a distortion correction rate in the main scanning direction is calculated based on

The distortion correction rate in the main scanning direction calculated by the main scanning direction distortion correction rate calculating means is an arbitrary position x in the sub-scanning direction of the virtual page outline.
(Spacing between the virtual page contour and the reference line at a predetermined position on the virtual page contour) / (Spacing between the virtual page contour and the reference line at an arbitrary position x in the sub-scanning direction)
The image distortion correction apparatus according to claim 2, wherein:

4. The image distortion correction apparatus according to claim 3, wherein the predetermined position on the virtual page outline is a boundary point between a straight line portion and a curved line portion of the virtual page outline.

The image distortion correction apparatus according to claim 3, wherein the predetermined position on the virtual page outline is located in a straight line portion of the virtual page outline.

The main scanning direction distortion correction unit is configured to convert the scan image obtained by pixel shifting in the main scanning direction so that the page outline, the ruled line, the character line, or the virtual page outline has a linear shape. The image distortion correction device according to claim 2, wherein the image distortion correction device is extended in the main scanning direction using the.

The main scanning direction distortion correction means performs a decompression process using a distortion correction factor in the main scanning direction at all positions in the sub-scanning direction of the page outline, the ruled line, the character line, or the virtual page outline. The image distortion correction apparatus according to claim 6.

The main scanning direction distortion correction means performs a decompression process using a distortion correction factor in the main scanning direction only at a position in the sub scanning direction corresponding to the curved portion of the page outline, the ruled line, the character line, or the virtual page outline. The image distortion correction apparatus according to claim 6, wherein the image distortion correction apparatus is applied.

The main scanning direction distortion correcting unit is configured to provide a sub-page corresponding to a boundary point between a straight line portion and a curved portion of the page outline, the ruled line, the character line, or the virtual page outline and a page binding portion of the scan image. 7. The image distortion correction apparatus according to claim 6, wherein an extension process using a distortion correction factor in the main scanning direction is performed only at a position in the scanning direction.

The main scanning direction distortion correction rate calculation unit, the main scanning direction distortion correction unit, the sub scanning direction distortion correction rate calculation unit, and the sub scanning direction distortion correction unit are executed independently for each left and right page of the scanned image. The image distortion correction apparatus according to claim 1, wherein the image distortion correction apparatus is used.

In an image distortion correction apparatus for correcting distortion of a scanned image obtained by reading a book document placed on a contact glass by an image reading unit, page outer shape determination means for determining whether or not a page outer shape exists in the scanned image; ,
A page outline image distortion correcting means for correcting distortion of the scan image based on the page outline when the page outline determining means determines that the page outline exists in the scanned image;
Ruled line / character line image distortion correction for correcting distortion of the scanned image based on ruled lines or character lines existing in the scanned image when the page outline determining unit determines that the page outline does not exist in the scanned image Means,
An image distortion correction apparatus comprising:

The page outline discrimination means is based on a count number obtained by counting the number of pixels whose density value is higher than a predetermined density value among pixels of the scan image in the sub-scanning direction of image reading by the image reading means. The image distortion correction apparatus according to claim 11, wherein a histogram in the main scanning direction is generated, and whether or not the page outline exists in the scanned image is determined based on the histogram pattern.

13. The image distortion correction apparatus according to claim 11, wherein a page binding portion is recognized using a position where the background density of the image is darkest in the sub-scanning direction as a binding portion boundary line in the scanned image.

In an image distortion correction apparatus that corrects distortion of a scanned image obtained by reading a book document placed on a contact glass by an image reading unit based on the shape of a ruled line extracted from the scanned image.
A histogram in the main scanning direction is formed on the basis of a count number obtained by counting the number of pixels whose density value is darker than a predetermined density value among the pixels of the scanned image in the sub-scanning direction of image reading by the image reading unit. A ruled line candidate extracting means for generating and extracting the ruled line candidate from the scanned image based on the histogram pattern;
Starting from an appropriate position on the ruled line candidate extracted by the ruled line candidate extracting means, the ruled line candidate is searched from the start point in the left-right direction, and the number of cut points at which the ruled line candidate is interrupted is accumulated. A ruled line discriminating means for discriminating the ruled line candidate from the ruled line when the number of cut points is less than a predetermined threshold;
An image distortion correction apparatus comprising:

15. The image distortion correction apparatus according to claim 14, wherein, among the ruled lines discriminated by the ruled line discriminating means, only those having a ruled line length longer than a preset threshold value are selected and used for distortion correction. .

Among the ruled lines discriminated by the ruled line discriminating means, only those having a part of the ruled lines that fall within a fixed width region on the left and right of the binding boundary line are selected and used for distortion correction. The image distortion correction apparatus according to claim 14 or 15.

When selecting one ruled line from each of the left and right pages for distortion correction, select the ruled line closest to the upper or lower page outline from among the ruled lines determined by the ruled line determining means. The image distortion correction apparatus according to claim 14, wherein the image distortion correction apparatus is used for distortion correction.

When the left and right pages are divided into upper and lower parts, and one of the four ruled lines is selected and used for distortion correction, the upper left and upper right of the ruled lines determined by the ruled line determination means 17. The distortion correction is performed by selecting the ruled line closest to the page outline at the upper end in the part and the page outline at the lower end in the lower left part and the lower right part, respectively. Image distortion correction device.

When one ruled line is selected from each of the left and right pages and used for distortion correction, the ruled line determined by the ruled line determination unit is selected and distorted by selecting the ruled line having the largest curvature on the left and right pages. The image distortion correction apparatus according to claim 14, wherein the image distortion correction apparatus is used for correction.

When dividing the left and right pages into upper and lower parts and selecting one ruled line for each of these four parts for use in distortion correction, the curved line is curved at each part among the ruled lines determined by the ruled line determining means. The image distortion correction apparatus according to any one of claims 14 to 16, wherein the ruled line having the largest is selected and used for distortion correction.

21. The image distortion correction apparatus according to claim 19, wherein a difference between coordinate values in the main scanning direction between the left and right end points of the ruled line is regarded as a curve size.

Approximate the vicinity of the binding boundary of the selected ruled line with a polynomial curve. If the shape of the estimated curve by polynomial approximation is inappropriate, exclude the ruled line and select another ruled line to correct the distortion. The image distortion correction apparatus according to claim 14, wherein the image distortion correction apparatus is used.

In an image distortion correction apparatus that corrects distortion of a scanned image obtained by reading a book document placed on a contact glass by an image reading unit based on the shape of a character line extracted from the scanned image.
Mainly generated based on the number of counts in the sub-scanning direction of the image reading by the image reading means, the number of times that the pixel density value of the scanned image is inverted between the darker pixel and the lighter pixel than the predetermined density value. The number of times the variance value relating to the histogram relating to the scanning direction and the pixel density value of the scanned image are inverted between the darker and lighter pixels than the predetermined density value are counted in the main scanning direction of the image reading by the image reading means. Comparing with a variance value relating to a histogram in the sub-scanning direction generated on the basis of the counted number, image distortion correction, comprising: a document discrimination means for discriminating whether the original is a horizontally written document or a vertically written document apparatus.

When the document determining unit determines that the document is a horizontally written document, only the character line having a length longer than a predetermined threshold is selected for the distortion correction. 24. The image distortion correction apparatus according to claim 23, characterized in that:

When the document determining unit determines that the document is a horizontally written document, only a part of the character line that falls within a constant width region on the left and right of the binding boundary line is included in the character line. 25. The image distortion correction apparatus according to claim 23, wherein the image distortion correction apparatus is selected and used for distortion correction.

When one character line is selected from each of the left and right pages for use in distortion correction, the character line closest to the top or bottom page outline is selected from among the character lines for use in distortion correction. The image distortion correction apparatus according to any one of claims 23 to 25.

When the left and right pages are divided into upper and lower parts and one of the four character lines is selected for distortion correction, the upper left page and the upper right part of the character line The image distortion correction apparatus according to any one of claims 23 to 25, wherein the character line closest to the outer shape of the page shape at the lower left and the lower right is selected for distortion correction. .

When selecting one character line from each of the left and right pages to be used for distortion correction, selecting the character lines having the greatest curvature in the left and right pages from among the character lines, and using them for distortion correction The image distortion correction apparatus according to any one of claims 23 to 25, wherein

When the left and right pages are divided into upper and lower parts and one of the character lines is selected for each of the four parts and used for distortion correction, the character having the largest curvature in each part in the character line. 26. The image distortion correction apparatus according to claim 23, wherein a line is selected and used for distortion correction.

30. The image distortion correction apparatus according to claim 28 or 29, wherein a difference in coordinate values in a main scanning direction between center points of character circumscribing rectangles on both left and right sides included in the character line is regarded as a curve size.

Approximate the vicinity of the binding part boundary line of the selected character line with a polynomial curve, and if the shape of the estimated curve by polynomial approximation is inappropriate, exclude the character line and select the other character line 31. The image distortion correction apparatus according to claim 23, wherein the image distortion correction apparatus is used for distortion correction.

When it is determined that the document is a vertically written document by the document determining means, and one character line is selected from each of the left and right pages for distortion correction, the first of the vertical character lines 24. The image distortion correction apparatus according to claim 23, wherein an outer shape obtained by connecting the upper and lowermost single characters is selected as one character line and used for distortion correction.

When the document determination means determines that the document is a vertically written document, the left and right pages are divided into upper and lower parts, and one character line is selected for each of the four parts to correct distortion. In the upper left and upper right parts, the outer shape of each character at the top of the vertical character line is considered as one line, and at the lower left and lower right part, each character at the bottom of the vertical character line. 24. The image distortion correction apparatus according to claim 23, wherein the outline obtained by connecting the two is regarded as one character line and selected for distortion correction.

When the outline of each character on the top of the vertical character line connected is regarded as one character line, the middle point of the upper side of the circumscribed rectangle of each character to be connected is regarded as the coordinate of that character, and the top of the vertical character line 34. The image according to claim 32 or 33, wherein when the outer shape obtained by concatenating each lower character is regarded as one character line, the midpoint of the lower side of the circumscribed rectangle of each character to be concatenated is regarded as the coordinates of the character. Distortion correction device.

35. The distortion is selected by selecting only the character line whose length is longer than a predetermined threshold among the outlines regarded as the character line as the character line, and performing the distortion correction. The image distortion correction apparatus according to any one of the above.

The distortion is corrected by selecting only one of the outer shapes regarded as the character line and a portion of the outer shape that falls within a constant width region on the left and right of the binding boundary line. Item 36. The image distortion correction device according to any one of Items 32 to 35.

The outer shape regarded as the character line when the shape of the estimated curve by polynomial approximation is approximated with a polynomial curve by approximating the vicinity of the binding portion boundary line of the outer shape regarded as the selected character line 37. The image distortion correction apparatus according to any one of claims 32 to 36, wherein the image is corrected and the other outline is selected for distortion correction.

Image reading means for reading a document image;
The image distortion correction apparatus according to any one of claims 1 to 10, which corrects a scanned image read by the image reading unit;
An image reading apparatus comprising:

Image reading means for reading a document image;
An image distortion correction apparatus according to any one of claims 11 to 37, which corrects a scanned image read by the image reading unit;
An image reading apparatus comprising:

Image reading means for reading a document image;
The image distortion correction apparatus according to any one of claims 1 to 10, which corrects a scanned image read by the image reading unit;
An image printing apparatus that prints an image on paper based on image data output from the image distortion correction apparatus;
An image forming apparatus comprising:

Image reading means for reading a document image;
An image distortion correction apparatus according to any one of claims 11 to 37, which corrects a scanned image read by the image reading unit;
An image printing apparatus that prints an image on paper based on image data output from the image distortion correction apparatus;
An image forming apparatus comprising:

A program for causing a computer to perform image distortion correction of a scanned image obtained by reading a book document placed on a contact glass with an image reading unit with a page binding portion parallel to a main scanning direction of image reading, On the computer,
A main scanning direction distortion correction rate calculation function for calculating a distortion correction rate in the main scanning direction based on the shape of the page outline, ruled line, character line of the scanned image or the image center line penetrating the scanned image in the sub-scanning direction;
A main scanning direction distortion correction function for correcting the distortion of the scan image by extending the scan image in the main scanning direction using the distortion correction ratio calculated by the distortion correction rate calculation function;
Sub-scanning direction distortion correction rate calculation that extracts a character circumscribing rectangle from the corrected image corrected by the main scanning direction distortion correction function and calculates a sub-scanning direction distortion correction rate based on the extracted shape of the character circumscribing rectangle Function and
A sub-scanning direction distortion correction function that expands the corrected image in the sub-scanning direction using the distortion correction rate calculated by the sub-scanning direction distortion correction rate calculation function, and corrects the distortion of the corrected image;
A program characterized by having executed.

  Scan that scans the book document placed on the contact glass with image reading means A program for causing a computer to execute image distortion correction of an image, wherein the computer
  A page outline determination function for determining whether or not a page outline exists in the scanned image;
  A page outline image distortion correction function for correcting distortion of the scan image based on the page outline when the page outline discrimination function determines that the page outline exists in the scan image;
  Ruled line / character line image distortion correction for correcting distortion of the scanned image based on ruled lines or character lines existing in the scanned image when the page outline determining function determines that the page outline does not exist in the scanned image Function and
  A program characterized by having executed.

  A program for causing a computer to perform image distortion correction of the scanned image based on the shape of the ruled line extracted from the scanned image obtained by reading the book document placed on the contact glass by the image reading unit,
  A histogram in the main scanning direction is formed on the basis of the count number obtained by counting the number of pixels whose density value is darker than a predetermined density value among the pixels of the scanned image in the sub-scanning direction of image reading by the image reading unit. A ruled line candidate extraction function for generating and extracting the ruled line candidates from the scanned image based on the histogram pattern;
  A suitable position on the ruled line candidate extracted by the ruled line candidate extraction function is used as a starting point, and the ruled line candidate is searched from the start point in the left-right direction, and the number of cutting points at which the ruled line candidate is interrupted is accumulated. A ruled line discriminating function for discriminating the ruled line candidate from the ruled line when the number of cutting points is less than a predetermined threshold;
  A program characterized by having executed.

A program for causing a computer to perform image distortion correction of the scan image based on the shape of a character line extracted from a scan image obtained by reading a book document placed on a contact glass by an image reading unit,
Mainly generated based on the number of counts in the sub-scanning direction of the image reading by the image reading means, the number of times that the pixel density value of the scanned image is inverted between the darker pixel and the lighter pixel than the predetermined density value. The number of times the variance value relating to the histogram relating to the scanning direction and the pixel density value of the scanned image are inverted between the darker and lighter pixels than the predetermined density value are counted in the main scanning direction of the image reading by the image reading means. A program for executing a document discrimination function for comparing a variance value relating to a histogram in the sub-scanning direction generated based on the counted number and discriminating whether the original is a horizontally written document or a vertically written document.