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EP0362595A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Image binarization apparatus

Assignee: Toshiba Corp
•
Filing: 1989-09-15
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Granted: —
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Expires: 2009-09-15
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Abstract

Abstract A feature-analyzing section (2) determines whether a given picture element included in image information supplied from a line buffer (1) represents a character portion or a photograph portion. In accordance with the determination made by the feature-analyzing section (2), a threshold value selection section (5) selects either a threshold value calculated by a first threshold value calculation section (6), and to be used in relation to character portion, or a threshold value calculated by a second threshold value calculation section (7), and to be used in relation to photograph portion. By using the threshold value selected by the threshold value selec­tion section, a binary-encoding section (8) binary-­encodes image information which is supplied thereto through a delay circuit (3). On the basis of the deter­mination made by the feature-analyzing section (2), a determination section (4) determines whether or not the given picture element represents a bold character por­tion. If the determination section (4) determines that the given picture element represents a bold character portion, a selection section (9) then selects a prede­termined value supplied from a signal generation section (10), in place of an output of the binary-encoding sec­tion (8).

Inventors

  • 👤 Hiroki C/O Int. Prop. Div. K.K. Toshiba Kanno
  • 👤 Hitoshi C/O Int. Prop. Div. K.K. Toshiba Yoneda
  • 👤 Hironobu C/O Int. Prop. Div. K.K. Toshiba Machida

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-05 04:02
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40062; G; G06; G06V; G06V30/00; G06V30/10; G06V30/16; G06V30/162

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 85 words
An image binarization apparatus for converting image information into binary-encoded image information, said image binarization apparatus characterized by comprising: determination means (4) for determining whether or not the image information has a bold character portion; means (8) for binary-encoding the image information by use of a predetermined threshold value; and means (9) for outputting a predetermined value in place of the binary-encoded image information outputted from the binary-encoding means (8), if the determination means (4) determines that the image information has a bold character portion.
Claim 2
Dependent Claim 85 words
An image binarization apparatus for converting image information into binary-encoded image information, said image binarization apparatus characterized by comprising: determination means (4) for determining whether or not the image information has a bold character portion; means (8) for binary-encoding the image information by use of a predetermined threshold value; and means (9) for outputting a predetermined value in place of the binary-encoded image information outputted from the binary-encoding means (8), if the determination means (4) determines that the image information has a bold character portion.
Claim 3
Dependent Claim 34 words
An apparatus according to claim 1, character­ized by further comprising first determination means (2) for determining whether image information of a predeter­mined range including an image of interest is character information or photograph information.
Claim 4
Dependent Claim 119 words
An apparatus according to claim 2, character­ized in that said first determination means (2) includes: first calculation means (21) for calculating an average image density of the predetermined range by use of the image information of the predetermined range including the image of interest; second calculation means (22, 23) for calculating a maximum image density difference of the image informa­tion of the predetermined range; means (24) for dividing an output of the second calculation means (22, 23) with an output of the first calculation means 21); and means (25) for comparing the result of the division performed by the dividing means (24) with a predeter­mined value, to thereby determine whether the image information is character information or photograph information.
Claim 5
Dependent Claim 106 words
An apparatus according to claim 3, character­ized in that said first calculation means (21) includes: a plurality of first adder means (21B to 21E) each for adding together a predetermined number of picture elements of the image information; means (21A) for supplying the picture elements to the plurality of first adder means (21B to 21E); second adder means (21F) for adding together sums obtained by the plurality of first adder means (21B to 21E); and means (21G) for dividing a sum obtained by the sec­ond adder means (21F) with the total number of picture elements, to thereby calculate an average image density of the image information.
Claim 6
Dependent Claim 77 words
An apparatus according to claim 3, character­ized in that said second calculation means (22, 23) includes: first comparator means (22B to 22E) for calculating maximum and minimum image densities of the image infor­mation in units of a predetermined number of picture elements; and second comparator means (22F, 22G) for calculating maximum and minimum densities of a local region on the basis of the maximum and minimum image densities pro­duced by the first comparator means (22B to 22E).
Claim 7
Dependent Claim 85 words
An apparatus according to claim 2, character­ized in that said binary-encoding means (8) includes: first threshold value calculation means (6) for calculating a threshold value used for binary-encoding the character information; second threshold value calculation means (7) for calculating a threshold value used for binary-encoding the photograph information; and threshold value selection means (5) for selecting one of the threshold values calculated by the first and second threshold value calculation means (6, 7), in accordance with the determination made by the first determination means (2).
Claim 8
Dependent Claim 30 words
An apparatus according to claim 6, character­ized in that said second threshold value calculation means (7) includes a memory (7A) for storing a threshold value corresponding to a dithering matrix.
Claim 9
Dependent Claim 57 words
An apparatus according to claim 2, character­ized in that said determination means (4) includes: means (37) for storing a predetermined signal corresponding to the bold character portion; and means (31 to 36) for setting a reading address of the storing means (37) in accordance with the results of the determination made by the first determination means (2).

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