EP0389164A2
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EP
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Pixel density converting apparatus
Assignee: Canon Inc
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Filing: 1990-03-13
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Granted: —
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Expires: 2010-03-13
Abstract
Abstract In a pixel density converting apparatus according to the present invention, a pixel density conversion element (2,3) for converting a pixel density by a factor of an arbitrary value, such as an element of the projection method or the linear interpolation method, a pixel density conversion element for increasing or decreasing a pixel density by a factor of an integer, such as an element of the majority or logical OR method, and a binarization element (6,7) for conducting binarization while correcting quantizing errors, such as an element of the error diffusion method or the average error minimizing method, are combined with each other with the advantages and disadvantages of the respective elements taken into consideration, so as to achieve excellent conversion whether or not the image on which pixel density conversion is conducted or an image area is a pseudo half-tone processed image. In consequence, excellent pixel density conversion is achieved on a binary image in which a pseudo halft-tone processed image and characters or line drawings are present in a mixed state.
Inventors
- 👤 Masami Kato
- 👤 Takao Kato
- 👤 Yasunori Hashimoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:20
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40075; H04N1/40062; H04N1/40068; H04N1/405; H04N1/4051; H04N1/4052
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
57 words
An image processing apparatus comprising: an input means for inputting binary image data; a conversion means for converting the input binary image data to multi-level image data; and a binarization means for binarizing the multi-level image data, wherein said binarization means includes a correction means for correcting error data generated when the multi-level image data is binarized.
Claim 2
Dependent Claim
57 words
An image processing apparatus comprising: an input means for inputting binary image data; a conversion means for converting the input binary image data to multi-level image data; and a binarization means for binarizing the multi-level image data, wherein said binarization means includes a correction means for correcting error data generated when the multi-level image data is binarized.
Claim 3
Dependent Claim
22 words
An image processing apparatus according to claim 1, wherein said binarization means binarizes the multi-level image data by the error diffusion method.
Claim 4
Dependent Claim
26 words
An image processing apparatus according to claim 1, wherein said conversion means converts the binary image data into the multi-level image data by the projection method.
Claim 5
Dependent Claim
27 words
An image processing apparatus according to claim 1, wherein said conversion means converts the binary image data into the multi-level image data by the linear interpolation method.
Claim 6
Dependent Claim
25 words
An image processing apparatus according to claim 1, wherein said input means inputs the binary image data which has been subjected to the half-tone process.
Claim 7
Dependent Claim
24 words
An image processing apparatus according to claim 1, further comprising a means for edge emphasizing the multi- image data obtained by said conversion means.
Claim 8
Dependent Claim
105 words
A pixel density converting apparatus for converting a pixel density of a binary image in which a pseudo half-tone processed image and characters or line drawings are present in a mixed state, comprising: a converted pixel operation means for operating a tone or luminance of a converted pixel from a tone or luminance of a predetermined original pixel in said binary image and a positional relation between said original pixel and said converted pixel; and a binarization means for binarizing the tone or luminance of said converted pixel which is the operation results while correcting a quantizing error generated when surrounding pixels have been binarized.
Claim 9
Dependent Claim
105 words
A pixel density converting apparatus for converting a pixel density of a binary image in which a pseudo half-tone processed image and characters or line drawings are present in a mixed state, comprising: a converted pixel operation means for operating a tone or luminance of a converted pixel from a tone or luminance of a predetermined original pixel in said binary image and a positional relation between said original pixel and said converted pixel; and a binarization means for binarizing the tone or luminance of said converted pixel which is the operation results while correcting a quantizing error generated when surrounding pixels have been binarized.
Claim 10
Dependent Claim
22 words
A pixel density converting apparatus according to claim 7, wherein said binarization means corrects the quantizing error by the error diffusion method.
Claim 11
Dependent Claim
23 words
A pixel density converting apparatus according to claim 7, wherein said binarization means corrects the quantizing error by the average error minimizing method.
Claim 12
Dependent Claim
152 words
A pixel density converting apparatus for converting a pixel density of a binary image in which a pseudo half-tone processed image and characters or line drawings are present in a mixed state, comprising: a converted pixel operation means for operating a tone or luminance of a converted pixel from a tone or luminance of a predetermined original pixel in said binary image and a positional relation between said original pixel and said converted pixel; a first binarization means for binarizing the tone or luminance of said converted pixel which is the operation results while correcting a quantizing error generated when surrounding pixels have been binarized; a second binarization means for conducting binarization without correcting said quantizing error; and a binarization selection means for selecting either of said first and second binarization means on the basis of determination as to whether or not an image area is a pseudo half-tone processed image area.
Claim 13
Dependent Claim
152 words
A pixel density converting apparatus for converting a pixel density of a binary image in which a pseudo half-tone processed image and characters or line drawings are present in a mixed state, comprising: a converted pixel operation means for operating a tone or luminance of a converted pixel from a tone or luminance of a predetermined original pixel in said binary image and a positional relation between said original pixel and said converted pixel; a first binarization means for binarizing the tone or luminance of said converted pixel which is the operation results while correcting a quantizing error generated when surrounding pixels have been binarized; a second binarization means for conducting binarization without correcting said quantizing error; and a binarization selection means for selecting either of said first and second binarization means on the basis of determination as to whether or not an image area is a pseudo half-tone processed image area.
Claim 14
Dependent Claim
36 words
A pixel density converting apparatus according to claim 7 or 10, further comprising a threshold level setting means for setting a threshold level used for binarization by said binarization means in accordance with a conversion factor.
Claim 15
Dependent Claim
25 words
A pixel density converting apparatus according to claim 7 or 10, wherein said converted pixel operation means operates the converted pixel by the projection method.
Claim 16
Dependent Claim
26 words
A pixel density converting apparatus according to claim 7 or 10, wherein said converted pixel operation means operates the converted pixel by the linear interpolation method.
Claim 17
Dependent Claim
59 words
A pixel density converting apparatus according to claim 7 or 10, further comprising a integral conversion means for increasing or decreasing the pixel density by a factor of an integer, and a conversion factor setting means for setting a factor for said converted pixel operation means and that for said integral conversion means in accordance with a conversion factor.
Claim 18
Dependent Claim
22 words
A pixel density converting apparatus according to claim 14, wherein said integral conversion means performs a conversion by the thinning out process.
Claim 19
Dependent Claim
21 words
A pixel density converting apparatus according to claim 14, wherein said integral conversion means performs a conversion by the majority process.
Claim 20
Dependent Claim
21 words
A pixel density converting apparatus according to claim 14, wherein said integral conversion means performs a conversion by the averaging process.
Claim 21
Dependent Claim
22 words
A pixel density converting apparatus according to claim 14, wherein said integral conversion means performs a conversion by the logical OR process.
Claim 22
Dependent Claim
97 words
A pixel density converting apparatus according to claim 7 or 10, further comprising a plurality of integral conversion means for increasing or decreasing the pixel density by a factor of an integer, an integral conversion means selection means for selecting either of said plurality of integral conversion means on the basis of determination as to whether or not an image area is a pseudo half-tone processed area, and a conversion factor setting means for setting a conversion factor for said converted pixel operation means and that for said integral conversion means in accordance with a conversion factor.
Claim 23
Dependent Claim
53 words
A pixel density converting apparatus according to claim 19, wherein said plurality of integral conversion means is a combination of a conversion means for conducting the thinning out process and a conversion means for conducting the majority process, and wherein the psuedo half-tone processed image area is processed by the thinning out method.
Claim 24
Dependent Claim
53 words
A pixel density converting apparatus according to claim 19, wherein said plurality of integral conversion means is a combination of a conversion means for conducting the thinning out process and a conversion means for conducting the averaging process, and wherein the psuedo half-tone processed image area is processed by the thinning out method.
Claim 25
Dependent Claim
54 words
A pixel density converting apparatus according to claim 19, wherein said plurality of integral conversion means is a combination of a conversion means for conducting the thinning out process and a conversion means for conducting the logical OR process, and wherein the psuedo half-tone processed image area is processed by the thinning out method.
Claim 26
Dependent Claim
30 words
A pixel density converting apparatus according to claim 7 or 10, further comprising an edge emphasis means which is interposed between said converted pixel operation means and said binarization means.
Claim 27
Dependent Claim
100 words
A pixel density converting apparatus for a binary image which employs the linear interpolation method, comprising: a pixel taking out means for taking out 4 original pixels surrounding a converted pixel on a projection surface formed by projecting a converted image onto an original image; a position operation means for operating a position of said converted pixel relative to said four original pixels; an area determination means for determining a predetermined area from said relative position obtained; and a converted pixel determination means for determining a value of said converted pixel from a logical expression determined by said determined area.
Claim 28
Dependent Claim
100 words
A pixel density converting apparatus for a binary image which employs the linear interpolation method, comprising: a pixel taking out means for taking out 4 original pixels surrounding a converted pixel on a projection surface formed by projecting a converted image onto an original image; a position operation means for operating a position of said converted pixel relative to said four original pixels; an area determination means for determining a predetermined area from said relative position obtained; and a converted pixel determination means for determining a value of said converted pixel from a logical expression determined by said determined area.
Claim 29
Dependent Claim
89 words
A pixel density converting apparatus for increasing or decreasing a number of pixels of a binary image by means of the projection means, comprising: an operation means for operating a tone or luminance of a converted pixel by limiting the number of pixels to be referred to which are to be subjected to conversion and which corresponds to 1 pixel obtained by the projecting method to a predetermined value and for approximating a tone of a pixel other than said limited pixels by tones of the adjacent reference pixels.
Claim 30
Dependent Claim
89 words
A pixel density converting apparatus for increasing or decreasing a number of pixels of a binary image by means of the projection means, comprising: an operation means for operating a tone or luminance of a converted pixel by limiting the number of pixels to be referred to which are to be subjected to conversion and which corresponds to 1 pixel obtained by the projecting method to a predetermined value and for approximating a tone of a pixel other than said limited pixels by tones of the adjacent reference pixels.
Claim 31
Dependent Claim
66 words
A pixel density converting apparatus for increasing or decreasing a number of pixels of a binary image by means of the projection means, comprising: an operation means for operating a tone or luminance of an objective pixel on the basis of overlapping of referred pixels on a pixel converted by the projection method whose one side has a length which is an integral power of 2.
Claim 32
Dependent Claim
66 words
A pixel density converting apparatus for increasing or decreasing a number of pixels of a binary image by means of the projection means, comprising: an operation means for operating a tone or luminance of an objective pixel on the basis of overlapping of referred pixels on a pixel converted by the projection method whose one side has a length which is an integral power of 2.
Claim 33
Dependent Claim
79 words
Image processing apparatus for changing the density of pixels relative to image features, which is capable of changing the said density by first and second methods, the first method preserving half-tone pixel densities better than the second method and the second method preserving thin lines better than the first method, and the apparatus selecting the method of changing the said density for a given portion of an input image in accordance with selection data relating to the given portion.
Claim 34
Dependent Claim
79 words
Image processing apparatus for changing the density of pixels relative to image features, which is capable of changing the said density by first and second methods, the first method preserving half-tone pixel densities better than the second method and the second method preserving thin lines better than the first method, and the apparatus selecting the method of changing the said density for a given portion of an input image in accordance with selection data relating to the given portion.
References Cited (Backward Citations)
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