US5467196A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Image forming apparatus which forms halftone images mixed with characters and fine lines
Assignee: Canon Inc
•
Filing: 1995-03-17
•
Granted: 1995-11-14
•
Expires: 2015-03-17
Abstract
Abstract When forming an image in which a half-tone image area such as photograph, screen, or the like and characters and fine lines exist the half-tone image area and the character and fine line portion are stably reproduced without deteriorating the picture qualities of both of them and, particularly, the character and fine line portion can be clearly reproduced. A digital image signal generated from an image reader is stored into an image memory on a pixel unit basis. A CPU subsequently reads the stored digital image signal and forms a frequency distribution function (density histogram) as a detection frequency of corresponding density values every pixel. The density level value of the portion in which the detection frequency is locally high is detected from the formed density histogram. The density level values are converted into at least one density value by a gradation correction circuit. An image having an excellent gradation reproducibility in a range from a low density portion to a high density portion can be formed by the converted density value.
Inventors
- 👤 Satoru Fukushima
- 👤 Sono Gu
- 👤 Yoshito Mizoguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:26
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/407; H04N1/4072; H04N1/4074
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
97 words
An image processing apparatus for processing an image defined by plural pixels, comprising: input means for inputting image data for each of said plural pixels of the image; discriminating means for discriminating whether each of said plural pixels of the image data represents a pixel from a predetermined type of image; forming means for forming a frequency distribution of density levels of image data for those pixels representing the predetermined type of image; and processing means for processing said image data inputted by said input means in accordance with the frequency distribution formed by said forming means.
Claim 2
Dependent Claim
97 words
An image processing apparatus for processing an image defined by plural pixels, comprising: input means for inputting image data for each of said plural pixels of the image; discriminating means for discriminating whether each of said plural pixels of the image data represents a pixel from a predetermined type of image; forming means for forming a frequency distribution of density levels of image data for those pixels representing the predetermined type of image; and processing means for processing said image data inputted by said input means in accordance with the frequency distribution formed by said forming means.
Claim 3
Dependent Claim
15 words
An apparatus according to claim 1, wherein said predetermined image type is a line image.
Claim 4
Dependent Claim
24 words
An apparatus according to claim 1, wherein said processing means includes density correction means for executing a density correction in accordance with said frequency.
Claim 5
Dependent Claim
28 words
An apparatus according to claim 1, further comprising image forming means for forming an image onto a medium based on the image data processed by said processing means.
Claim 6
Dependent Claim
16 words
An apparatus according to claim 4, wherein said image forming means is a laser beam printer.
Claim 7
Dependent Claim
16 words
An apparatus according to claim 4, wherein said image forming means is a bubble jet printer.
Claim 8
Dependent Claim
89 words
An image processing method for processing an image defined by plural pixels, comprising the steps of: inputting image data for each of said plural pixels of the image; discriminating whether each of said plural pixels of the image data represents a pixel from a predetermined type of image; forming a frequency distribution of density levels of the image data for those pixels representing the predetermined type of image; and processing said image data inputted in said input step in accordance with a frequency distribution formed in said forming step.
Claim 9
Dependent Claim
89 words
An image processing method for processing an image defined by plural pixels, comprising the steps of: inputting image data for each of said plural pixels of the image; discriminating whether each of said plural pixels of the image data represents a pixel from a predetermined type of image; forming a frequency distribution of density levels of the image data for those pixels representing the predetermined type of image; and processing said image data inputted in said input step in accordance with a frequency distribution formed in said forming step.
Claim 10
Dependent Claim
91 words
An image processing apparatus for processing an image defined by plural pixels, comprising: input means for inputting image data for each of said plural pixels of the image; discriminating means for discriminating whether each of said plural pixels of the image data represents a pixel from a line image; arithmetic operating means for calculating a frequency distribution of density levels of image data for those pixels representing the line image; and correcting means for correcting said input image data in accordance with the frequency distribution calculated by said arithmetic operating means.
Claim 11
Dependent Claim
91 words
An image processing apparatus for processing an image defined by plural pixels, comprising: input means for inputting image data for each of said plural pixels of the image; discriminating means for discriminating whether each of said plural pixels of the image data represents a pixel from a line image; arithmetic operating means for calculating a frequency distribution of density levels of image data for those pixels representing the line image; and correcting means for correcting said input image data in accordance with the frequency distribution calculated by said arithmetic operating means.
Claim 12
Dependent Claim
28 words
An apparatus according to claim 8, further comprising image forming means for forming an image onto a medium based on the image data connected by said correcting means.
Claim 13
Dependent Claim
16 words
An apparatus according to claim 9, wherein said image forming means is a laser beam printer.
Claim 14
Dependent Claim
16 words
An apparatus according to claim 9, wherein said image forming means is a bubble jet printer.
Claim 15
Dependent Claim
80 words
An image processing method for processing an image defined by plural pixels, comprising the steps of: inputting image data for each of said plural pixels of the image; discriminating whether each of said plural pixels of the image data represents a pixel from a line image; calculating a frequency distribution of density levels of image data for those pixels representing the line image; and correcting said input image data in accordance with the frequency distribution calculated in said calculating step.
Claim 16
Dependent Claim
80 words
An image processing method for processing an image defined by plural pixels, comprising the steps of: inputting image data for each of said plural pixels of the image; discriminating whether each of said plural pixels of the image data represents a pixel from a line image; calculating a frequency distribution of density levels of image data for those pixels representing the line image; and correcting said input image data in accordance with the frequency distribution calculated in said calculating step.
Claim 17
Dependent Claim
136 words
A copying apparatus comprising: reading means for performing first and second scannings of each of plural pixels defined by an original, and for generating image data for each of said plural pixels; discriminating means for discriminating whether each of said plural pixels of the image data represents a pixel from a predetermined type of image; arithmetic operating means for calculating a frequency distribution of density levels of image data for those pixels representing the predetermined type of image; and processing means for processing the image data generated by said reading means in accordance with the frequency distribution calculated by said arithmetic operating means, wherein said discriminating means and said arithmetic operating means operatively correspond to the first scanning by said reading means, and said processing means operatively corresponds to the second scanning by said reading means.
Claim 18
Dependent Claim
136 words
A copying apparatus comprising: reading means for performing first and second scannings of each of plural pixels defined by an original, and for generating image data for each of said plural pixels; discriminating means for discriminating whether each of said plural pixels of the image data represents a pixel from a predetermined type of image; arithmetic operating means for calculating a frequency distribution of density levels of image data for those pixels representing the predetermined type of image; and processing means for processing the image data generated by said reading means in accordance with the frequency distribution calculated by said arithmetic operating means, wherein said discriminating means and said arithmetic operating means operatively correspond to the first scanning by said reading means, and said processing means operatively corresponds to the second scanning by said reading means.
Claim 19
Dependent Claim
28 words
An apparatus according to claim 13, further comprising image forming means for forming an image onto a medium based on the image data processed by said processing means.
Claim 20
Dependent Claim
16 words
An apparatus according to claim 14, wherein said image forming means is a laser beam printer.
Claim 21
Dependent Claim
16 words
An apparatus according to claim 14, wherein said image forming means is a bubble jet printer.
References Cited (Backward Citations)
US4352553A
Cited
US4667228A
Cited
US4931864A
Cited
US5086486A
Cited
US4907286A
Cited
US4837450A
Cited
US4800442A
Cited
US4887167A
Cited
US5075788A
Cited
US4903145A
Cited
US4969053A
Cited
US5125045A
Cited
US4958219A
Cited
US5053888A
Cited
US5091967A
Cited
US5031034A
Cited
US5016118A
Cited
US5153925A
Cited
US5117293A
Cited
US5119207A
Cited
US5172132A
Cited
US5173783A
Cited
US5133022A
Cited
US5212741A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-11-13 | 1999-05-15 | 1999-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-13 | 2003-05-15 | 2003-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-13 | 2007-05-15 | 2007-11-14 | $7700.00 | Window Closed / Lapsed |