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EP0334518A2
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Image forming apparatus
Assignee: Canon Inc
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Filing: 1989-03-10
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Granted: —
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Expires: 2009-03-10
Abstract
Abstract In an image forming apparatus for forming an ordinary copy or a tonality image for an original image for a printing press, original image data is divided into a predetermined area, and pixel density within the area is subjected to a density conversion in accordance with screen half-toning information which will increase density information toward the approximate center of these pixels, by way of example. The original image data or the density-converted image data is converted into a binary-coded signal conforming to the density, and an output image is formed in accordance therewith. Preferably, plural types of non-linear correction tables are provided and a tone-conversion is performed selecting a correction table for every pixel or every line of the density-converted image data. Preferably, the original image data is binary coded by a pattern signal having a long period, and the density-converted image data is binary coded by a pattern signal having a short period. The foregoing is applied to color-separated image data of each color. Preferably, the image data is divided, in accordance with color, into predetermined areas having the same or a different number of pixels, or into predetermined areas having a planar phase which differs for each color, and a screen angle is applied thereto.
Inventors
- 👤 Kimiyoshi Hayashi
- 👤 Hitoshi Arai
- 👤 Kazuhiko Hirooka
- 👤 Toshio Honma
- 👤 Kenichi Takeda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 19:20
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/23; H04N1/29; G; G03; G03G; G03G13/00; G03G13/01; G03G13/013; G03G13/0133; H04N1/40; H04N1/40025; H04N1/40037; H04N1/46; H04N1/50; H04N1/506
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
81 words
An image forming apparatus which comprises: density converting means for dividing image data into a predetermined area and subjecting pixel density within the area to a density conversion in accordance with predetermined screen half-toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; and image forming means for forming an output image in accordance with the binary-coded signal outputted by said binary coding means.
Claim 2
Dependent Claim
81 words
An image forming apparatus which comprises: density converting means for dividing image data into a predetermined area and subjecting pixel density within the area to a density conversion in accordance with predetermined screen half-toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; and image forming means for forming an output image in accordance with the binary-coded signal outputted by said binary coding means.
Claim 3
Dependent Claim
83 words
The apparatus according to claim 1, wherein said density converting means subjects an output density V ij ′ of each pixel of interest to a density conversion in accordance with screen half-toning information based on the following equation: V ij ′ = nV ij - r(P ij - 1) 0 ≦ V ij ′ ≦ r where V ij : input density of each pixel of interest n : number of pixels in predetermined area r : maximum density Pij : weighting coefficient
Claim 4
Dependent Claim
28 words
The apparatus according to claim 2, wherein said weighting coefficient comprises information which reduces the number of coefficient toward the approximate center pixel position of said predetermined area.
Claim 5
Dependent Claim
34 words
The apparatus according to claim 1, wherein said binary coding means comprises pulse-width modulated signal output means for tone-processing the image data density-converted by said density converting means and outputting a pulse-width modulated signal.
Claim 6
Dependent Claim
98 words
An image forming apparatus which comprises: density converting means for dividing image data into a predetermined area and subjecting pixel density within the area to a density conversion in accordance with predetermined screen half-toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; image forming means for forming an output image in accordance with the binary-coded signal outputted by said binary coding means; and combining means for combining a specific pattern with an outputted image produced by said image forming means.
Claim 7
Dependent Claim
98 words
An image forming apparatus which comprises: density converting means for dividing image data into a predetermined area and subjecting pixel density within the area to a density conversion in accordance with predetermined screen half-toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; image forming means for forming an output image in accordance with the binary-coded signal outputted by said binary coding means; and combining means for combining a specific pattern with an outputted image produced by said image forming means.
Claim 8
Dependent Claim
42 words
An image forming apparatus according to claim 5, further comprising: pattern signal generating means for generating a pattern signal corresponding to said specific pattern: and means for inputting said pattern signal to said binary coding means when said combining means is activated.
Claim 9
Dependent Claim
26 words
An image forming apparatus according to claim 5, further comprising a location designationg means for designating a location where the specific pattern is to be combined.
Claim 10
Dependent Claim
36 words
An image forming apparatus according to claim 5, wherein said binary coding means comprises pulse-width modulated signal output means for tone-processing the image data density-converted by said density converting means, and outputting a pulse-width modulated signal.
Claim 11
Dependent Claim
62 words
An image forming apparatus which comprises: tone-processing means for tone-processing color-separated image data of each color; image forming means for forming images the number whereof corresponds to the number of color separation in accordance with the tone-processed image data by said tone-processing means; and pattern combining means for combining a specific pattern to the output image produced by said image forming means.
Claim 12
Dependent Claim
62 words
An image forming apparatus which comprises: tone-processing means for tone-processing color-separated image data of each color; image forming means for forming images the number whereof corresponds to the number of color separation in accordance with the tone-processed image data by said tone-processing means; and pattern combining means for combining a specific pattern to the output image produced by said image forming means.
Claim 13
Dependent Claim
29 words
An image forming apparatus according to claim 9, wherein said pattern combining means further comprises pattern signal generating means for generating a pattern signal corresponding to said specific pattern.
Claim 14
Dependent Claim
28 words
An image forming apparatus according claim 10, wherein said tone-processing means comprises a pulse-width modulated signal output means for processing the image data and outputting pulse-width modulated signal.
Claim 15
Dependent Claim
28 words
An image forming apparatus according to claim 11, further comprising means for selectively applying said image data and said pattern signal to said pulse-width modulated signal output means.
Claim 16
Dependent Claim
153 words
An image forming apparatus which comprises: operating means for designating an image output mode; density converting means for subjecting color-separated image data of each color to a density conversion in accordance with predetermined screen half-toning information; pulse-width modulated signal output means for tone-processing the color-separated image data of each color or the image data density-converted by said density converting means, and outputting a pulse-width modulated signal; and image forming means for selectively setting, in dependence upon a designation from said operating means, a mode in which one reproduced image is formed on the same recording medium by the pulse-width modulated signal based on the color-separated image data of each color, and a mode in which a reproduced image corresponding to each color is formed on recording media, the number whereof corresponds to the number of color separations, by the pulse-width modulated signal based on the image data density-converted by said density converting means.
Claim 17
Dependent Claim
153 words
An image forming apparatus which comprises: operating means for designating an image output mode; density converting means for subjecting color-separated image data of each color to a density conversion in accordance with predetermined screen half-toning information; pulse-width modulated signal output means for tone-processing the color-separated image data of each color or the image data density-converted by said density converting means, and outputting a pulse-width modulated signal; and image forming means for selectively setting, in dependence upon a designation from said operating means, a mode in which one reproduced image is formed on the same recording medium by the pulse-width modulated signal based on the color-separated image data of each color, and a mode in which a reproduced image corresponding to each color is formed on recording media, the number whereof corresponds to the number of color separations, by the pulse-width modulated signal based on the image data density-converted by said density converting means.
Claim 18
Dependent Claim
51 words
The apparatus according to claim 13, wherein said pulse-width modulated signal output means converts said color-separated image data into a pulse-width modulated signal by a pattern signal having a relatively long period, and converts said density-converted data into a pulse-width modulated signal by a pattern signal having a relatively short period.
Claim 19
Dependent Claim
78 words
An image forming apparatus which comprises: pulse-width modulated signal output means for tone-processing color-separated image data of each color and outputting pulse-width modulated signals corresponding to respective ones of the colors; and image forming means for forming, on different recording media, images the number whereof corresponds to the number of color separations in accordance with the pulse-width modulated signals which correspond to respective ones of the colors and which are outputted by said pulse-width modulated signal output means.
Claim 20
Dependent Claim
78 words
An image forming apparatus which comprises: pulse-width modulated signal output means for tone-processing color-separated image data of each color and outputting pulse-width modulated signals corresponding to respective ones of the colors; and image forming means for forming, on different recording media, images the number whereof corresponds to the number of color separations in accordance with the pulse-width modulated signals which correspond to respective ones of the colors and which are outputted by said pulse-width modulated signal output means.
Claim 21
Dependent Claim
108 words
The apparatus according to claim 15, further comprising density converting means for subjecting said color-separated image data of each color to a density conversion in accordance with predetermined screen half-toning information; said density converting means subjecting an output density V ij ′ of each pixel of interest to a density conversion in accordance with screen half-toning information based on the following equation: V ij ′ = nV ij - r(P ij - 1) 0 ≦ V ij ′ ≦ r where V ij : input density of each pixel of interest n : number of pixels in predetermined area r : maximum density P ij : weighting coefficient
Claim 22
Dependent Claim
82 words
An image forming apparatus which comprises: density converting means for subjecting color-separated image data of each color to a density conversion in accordance with predetermined screen half-toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; and image forming means for forming images the number whereof corresponds to the number of color separations in accordance with the binary-coded signal outputted by said binary coding means.
Claim 23
Dependent Claim
82 words
An image forming apparatus which comprises: density converting means for subjecting color-separated image data of each color to a density conversion in accordance with predetermined screen half-toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; and image forming means for forming images the number whereof corresponds to the number of color separations in accordance with the binary-coded signal outputted by said binary coding means.
Claim 24
Dependent Claim
84 words
The apparatus according to claim 17, wherein said density converting means subjects an output density V ij ′ of each pixel of interest to a density conversion in accordance with screen half-toning information based on the following equation: V ij ′ = nV ij - r(P ij - 1) 0 ≦ V ij ′ ≦ r where V ij : input density of each pixel of interest n : number of pixels in predetermined area r : maximum density P ij : weighting coefficient
Claim 25
Dependent Claim
29 words
The apparatus according to claim 17, wherein said image forming means forms an image of a screen angle which differs for every item of image data of each color.
Claim 26
Dependent Claim
33 words
The apparatus according to claim 19, wherein said screen angle is within a range of 20° - 70° for magenta or cyan, 0° - 20° for yellow and 70° - 90° for black.
Claim 27
Dependent Claim
102 words
An image forming apparatus which comprises: density converting means for subjecting color-separated image data of each color to a density conversion in accordance with predetermined screen half toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; and image forming means for forming images the number whereof corresponds to the number of color separations in accordance with the binary-coded signal outputted by said binary coding means; and pattern combining means for combining a specific pattern on the output image outputted by said image forming means.
Claim 28
Dependent Claim
102 words
An image forming apparatus which comprises: density converting means for subjecting color-separated image data of each color to a density conversion in accordance with predetermined screen half toning information; binary coding means for converting the image data, which has been density-converted by said density converting means, into a binary-coded signal conforming to the density; and image forming means for forming images the number whereof corresponds to the number of color separations in accordance with the binary-coded signal outputted by said binary coding means; and pattern combining means for combining a specific pattern on the output image outputted by said image forming means.
Claim 29
Dependent Claim
28 words
An image forming apparatus according to claim 21, wherein said pattern combining means comprises pattern signal generating means for generating a pattern signal corresponding to said specific pattern.
Claim 30
Dependent Claim
31 words
An image forming apparatus according to claim 22, wherein said binary coding means comprises a pulse-width modulated signal output means for processing the image data and outputting a pulse-width modulated signal.
Claim 31
Dependent Claim
28 words
An image forming apparatus according to claim 23, further comprising means for selectively applying said image data and said pattern signal to said pulse-width modulated signal output means.
Claim 32
Dependent Claim
84 words
An image forming apparatus which comprises: density converting means for subjecting image data to a density conversion in accordance with predetermined screen half-toning information; tone converting means for performing a density tone conversion on the image data density-converted by said density converting means; binary coding means for converting the image data, which has been tone-converted by said tone converting means, into a binary-coded signal conforming to the density thereof; and image forming means for forming an output image in accordance with the binary-coded signal.
Claim 33
Dependent Claim
84 words
An image forming apparatus which comprises: density converting means for subjecting image data to a density conversion in accordance with predetermined screen half-toning information; tone converting means for performing a density tone conversion on the image data density-converted by said density converting means; binary coding means for converting the image data, which has been tone-converted by said tone converting means, into a binary-coded signal conforming to the density thereof; and image forming means for forming an output image in accordance with the binary-coded signal.
Claim 34
Dependent Claim
58 words
An image forming apparatus which comprises: tone processing means for tone-processing color-separated image data of each color; developing means for developing the image of each color in accordance with the image data tone-processed by said tone processing means; and transfer means for transferring the developed images to the same transfer material in order starting from a yellow image.
Claim 35
Dependent Claim
58 words
An image forming apparatus which comprises: tone processing means for tone-processing color-separated image data of each color; developing means for developing the image of each color in accordance with the image data tone-processed by said tone processing means; and transfer means for transferring the developed images to the same transfer material in order starting from a yellow image.
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