EP0496600A2
Expired / Lapsed
EP
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Image processing apparatus
Assignee: Canon Inc
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Filing: 1992-01-22
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Granted: —
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Expires: 2012-01-22
Abstract
Abstract [Purpose] In a reproduced image in accordance with pseudo-half-tone processing, it is an object to prevent low-density areas (highlighted portions) of the image, to which the human eye is most sensitive, from graininess and obtain a reproduced image of high picture quality with little sense of graininess without increasing the size of a page memory. [Structure] The binary data monitoring unit 400 detects low-density areas of binarized image by the binarizing circuit 300. The resolution converting circuit 500 divides dots which exist in the low-density area into dots of higher resolution, whereby improving the resolution. Then, the output unit 600 outputs and records the image. This results in obtaining a reproduced image of high picture quality with little sense of graininess without increasing the size of a page memory.
Inventors
- 👤 Yuichi Bannai
- 👤 Toshihiko Sato
- 👤 Kunihiro Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:55
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4051; H04N1/4052
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
131 words
An image processing method for applying binarizing processing to multivalue image data so as to produce binary image data, reproducing an image having shades of light and dark based upon the binary image data, and outputting the image, comprising the steps of: an input step of inputting the multivalue image data; a binarizing step of binarizing the multivalue image data; a detecting step of detecting a pixel, which is an isolated point, in the image data binarized at said binarizing step; a converting step of dividing information indicative of the pixel of the isolated point, which pixel has been detected at said detecting step, into a plurality of pixels and outputting this information; and an output step of outputting a light-and-dark image based upon an output obtained at said converting step.
Claim 2
Dependent Claim
29 words
The method according to claim 1, wherein said binarizing step is such that the binarizing processing applied to the multivalue image data is executed by a error diffusion method.
Claim 3
Dependent Claim
122 words
An image processing apparatus for applying binarizing processing to multivalue image data so as to produce binary image data, reproducing an image having shades of light and dark based upon the binary image data, and outputting the image, comprising: input means for inputting the multivalue image data; binarizing means for binarizing the multivalue image data; detecting means for detecting a pixel, which is an isolated point, in the image data binarized by said binarizing means; converting means for dividing information indicative of the pixel of the isolated point, which pixel has been detected by said detecting means, into a plurality of pixels and outputting this information; and output means for outputting a light-and-dark image based upon an output from said converting means.
Claim 4
Dependent Claim
61 words
The apparatus according to claim 3, wherein said input means includes: multivalue image memory means for storing multivalue image data corresponding to one page of a light-and-dark image outputted by said output means; and buffer means for buffering a multivalue image data input from said multivalue image memory means and an output of the multivalue image data to said binarizing means.
Claim 5
Dependent Claim
32 words
The apparatus according to claim 3, wherein said multivalue image data is data in which one pixel is expressed by eight bits and tones are capable of being expressed in 256 steps.
Claim 6
Dependent Claim
58 words
The apparatus according to claim 3, wherein said detecting means includes: searching means which searches for pixels peripheral to said pixel, with regard to each pixel of the binarized image data, in order to detect the isolated point; and feedback means for feeding the result of the search performed by said searching means back to said binarizing means.
Claim 7
Dependent Claim
43 words
The apparatus according to claim 3, further comprising search-range control means for performing control in such a manner that the range within which the pixels peripheral to said pixel are searched for is decided in accordance with the values of the multivalue data.
Claim 8
Dependent Claim
37 words
The apparatus according to claim 6, wherein said search means includes: narrow-area searching means which searches for peripheral pixels comparatively near said pixel; and wide-area searching means which searches for peripheral pixels comparatively far from said pixel.
Claim 9
Dependent Claim
24 words
The apparatus according to claim 8, wherein an area searched by said narrow-area searching means and said wide-area searching means is a rectangular area.
Claim 10
Dependent Claim
29 words
The apparatus according to claim 8, wherein said narrow-area searching means detects, by searching for the peripheral pixels, whether said peripheral pixels have a pixel whose value is "1".
Claim 11
Dependent Claim
29 words
The apparatus according to claim 8, wherein said wide-area searching means detects, by searching for the peripheral pixels, whether said peripheral pixels have a pixel whose value is "1".
Claim 12
Dependent Claim
228 words
The apparatus according to claim 3, wherein said converting means includes: discriminating means for determining whether there is a pixel whose value is "1" in the binarized image at the periphery of the pixel of the isolated point detected by said detecting means; first diffusing means for diffusing the value of the pixel of the isolated point near the isolated point in a case where said discriminating means has determined that there is a pixel whose value is "1" comparatively near the pixel of the isolated point; second diffusing means for diffusing the value of the pixel of the isolated point far from the isolated point in a case where said discriminating means has determined that there is a pixel whose value is "1" comparatively far from the pixel of the isolated point; third diffusing means for diffusing the value of the pixel of the isolated point to a pixel alongside the isolated point in a case where said discriminating means has determined that there are pixels whose value is "1" comparatively near and comparatively far from the pixel of the isolated point; and control means for performing control in such a manner that resolution is multiplied any integral number of times in the longitudinal direction and/or transverse direction or in the diagonal direction of the image having shades of light and dark outputted by said output means.
Claim 13
Dependent Claim
44 words
The apparatus according to claim 12, wherein said converting means further includes binary image memory means for storing a predetermined number of lines of binary image data diffused by said first, second and third diffusing means and increased in resolution by said control means.
Claim 14
Dependent Claim
84 words
The apparatus according to claim 12, wherein said first diffusing means includes: first suppressing means for performing suppression in such a manner that the value of the pixel of the isolated point will not be diffused from the isolated point in a case where the value of the pixel of the isolated point is "0"; and a look-up table (LUT), which corresponds to the magnification of the conversion of resolution, having position information for diffusing the value of the pixel of the isolated point.
Claim 15
Dependent Claim
84 words
The apparatus according to claim 12, wherein said second diffusing means includes: second suppressing means for performing suppression in such a manner that the value of the pixel of the isolated point will not be diffused from the isolated point in a case where the value of the pixel of the isolated point is "0"; and a look-up table (LUT), which corresponds to the magnification of the conversion of resolution, having position information for diffusing the value of the pixel of the isolated point.
Claim 16
Dependent Claim
84 words
The apparatus according to claim 12, wherein said third diffusing means includes: third suppressing means for performing suppression in such a manner that the value of the pixel of the isolated point will not be diffused from the isolated point in a case where the value of the pixel of the isolated point is "0"; and a look-up table (LUT), which corresponds to the magnification of the conversion of resolution, having position information for diffusing the value of the pixel of the isolated point.
Claim 17
Dependent Claim
19 words
The apparatus according to claim 3, wherein said output means includes a digital facsimile machine or a digital printer.
Claim 18
Independent Claim
21 words
A method of processing binary image data, characterised by dividing data representing an isolated point into a plurality of half-tone areas.
References Cited (Backward Citations)
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