Image analysis – Image transformation or preprocessing – Measuring image properties
Reexamination Certificate
1999-01-20
2004-10-12
Patel, Jayanti K. (Department: 2625)
Image analysis
Image transformation or preprocessing
Measuring image properties
C382S291000, C382S296000, C382S297000, C358S488000, C358S496000
Reexamination Certificate
active
06804414
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image status detecting apparatus detecting a status of an image (particularly a document image) inputted through an image input device such as a scanner and relates to a document image correcting apparatus correcting an image inputted through an image input device into an erecting image. Particularly, the present invention relates to a document image correcting apparatus detecting a direction of a document by detecting a rotated angle and an existence of mirroring (reflected-inversion) of a character among characters inputted in a state that these are rotated and mirrored (reflectively inverted).
2. Description of the Related Art
In late years, as an image scanner is used as an input device for a document image. Small handy scanners for manual operation, which are carried easily, are developed and manufactured in addition to fixed-flatbed scanners which are conventional image scanners.
As to handy scanners, an user can scan in any direction, namely, an user can use a handy scanner flexibly. However, there are cases in that a rotated image and a mirrored image are read as images due to a reading (scanning) direction which is a relative direction between a sheet and a scanner, therefore, it is necessary to correct the image by rotating or rotating after scanning. For example, this case occurs when a document written horizontally is read from the top of the document.
Further, there is a possibility in that a whole document is mirrored and inputted. In a document written horizontally, a sentence is usually written from left to right. When this document is scanned from right to left, the inputted characters are mirrored characters. Such mirroring occurs when a back and a face of a permeable sheet such as an OHP sheet is reversed in spite of a fixed-flatbed scanner.
Thus, when a process such as character recognition is applied to the inputted document image, the document is not inputted in a proper direction and an accuracy of the character recognition lowers in a case that a character is rotated and mirrored, therefore, it is necessary to correct the document image into an erecting image after inputting document image in order to direct the document read in this way to a correct direction.
There are conventional document image erecting method such as Japan Patent Application Laid-Open 8-212298 and Japan Patent Application Laid-Open 7-28945.
Japan Patent Application Laid-Open 8-212298 discloses, as shown in
FIG. 31
, a technique in which an inputted character is recognized from four directions such as angles of 0°, 90°, 180° and 270°, an accuracy value of the character recognition is obtained, and the direction having the highest accuracy value is judged as the document direction.
However, Japan Patent Application Laid-Open 8-212298 gives no description that a mirrored character is corrected. For example, though a symmetric character is read conversely, there is a high possibility in that the apparatus recognizes this character as normal. Further, the accuracy value is obtained from the character recognition result regardless of the reading direction, therefore, there is a case that the accuracy value becomes higher than a character read in a correct direction.
Japan Patent Application Laid-Open 7-28945 discloses a technique, in which a character is unsuitable to judge the direction of document, such as a left-right symmetric character, a upside-down symmetric character, a point symmetric character, a character which looks like another character when turned upside down, a character which looks like another character when mirrored, therefore, when this character is clipped, the clipping process is re-executed.
SUMMARY OF THE INVENTION
The present invention is developed in order to solve this problem, and has its object to provide a document image correcting apparatus detecting a status of a document image inputted through an input device such as a scanner with an image status detecting apparatus, and automatically correcting document images into a proper image even if a rotated document image, a reversed document image or a rotated/mirrored image.
The present invention has another object to determine a character to be extracted based on a specific condition when a character is extracted in order to use only specific kinds of characters for judging the rotation and the mirroring of the document. Concretely, characters used for judgment are selected by using a value of which a standard value varies in accordance with a kind of a character, such as a length-breath ratio, a black (white) pixel ratio and a pixel size.
The present invention adapts the following in order to solve the above-described problem.
The first aspect of the present invention is an image status detecting apparatus detecting whether or not a character image inputted through an image input unit is mirrored horizontally or vertically and/or what degree the character image is rotated compared with an original character. The image status detecting apparatus comprises an image converting unit for rotating and for mirroring the character image inputted through the image input unit; a character recognizing unit for referring a character recognition dictionary storing character feature information and for obtaining candidate characters resemble to the character image mirrored and rotated by the image converting unit and a recognition rate indicating a degree of recognition certainty; and a conversion procedure detecting unit for detecting, based on the candidate characters and the recognition rate obtained by the character recognizing unit, a rotation angle and an existence of mirroring needed to direct the character image to a proper direction.
The second aspect of the present invention is a document image correcting apparatus using this image status detecting apparatus. The document image correcting apparatus comprises a character image storing unit for storing a character image inputted through image input unit; an image status detecting unit for detecting whether or not the character image stored in the character image storing unit is mirrored and what degree the character image is rotated compared with an original character; and an image correcting unit for directing the character image stored in the character image storing means to the proper direction based on a detected result of the image status detecting means.
Further, the image status detecting units may comprise an image converting unit for rotating and for mirroring the character image inputted through the image input unit; a character recognizing unit for referring a character recognition dictionary storing character feature information and for obtaining candidate characters resemble to the character image mirrored and rotated by the image converting unit and a recognition rate indicating a degree of recognition certainty; and a conversion procedure detecting unit for detecting, based on the candidate characters and the recognition rate obtained by the character recognizing means, a rotation angle and an existence of mirroring needed to direct the original character image to a proper direction.
In these aspects, a scanner, more particularly, a hand-held scanner is generally used as the image input unit. A document image including a line (and lines) of plural characters is read by the scanner. Then, it is preferable that the document image is temporarily stored in the document image storing unit (such as a memory) and then at one or more specific character is extracted from the document image and is stored in the character image storing unit (such as a memory).
When a hand-held scanner is used, the read image is mirrored in a case that the scanning direction differs from the original document direction. Thus, the image status detecting unit detects whether or not the character image stored in the character image storing unit is mirrored as to the original character. When the image status detecting unit judges that the character image is mirrored, the image correcting unit
Chiba Hirotaka
Noda Tsugio
Sakai Kenichiro
Kassa Yosef
Patel Jayanti K.
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