EP0849934A2
Expired / Lapsed
EP
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Image processing apparatus and image processing method
Assignee: Canon Inc
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Filing: 1997-12-19
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Granted: —
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Expires: 2017-12-19
Abstract
Abstract An image processing method and apparatus employing a cyclic error diffusion method for binarizing a basic image represented by multivalued data, in order to form a high quality image represented in pseudo tones with reduced noise caused by the binarization. When each pixel is sequentially binarized by applying the error diffusion method to the basic image, errors generated at one edge of the basic image are incorporated into the edge of the other side, and error diffusion is performed while incorporating the errors. Furthermore, a supplemental image, which is a part of the basic image, is added to the upper edge of the basic image to form a combined image, and the error diffusion processing is performed by utilizing the combined image. Upon completing the binarization processing, binary data in the lower edge portion of the supplemental image is compared with binary data in the corresponding lower edge portion of the basic image, and pixel values in the area are corrected based on the comparison result.
Inventors
- 👤 Akio Iino
- 👤 Hisashi Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 14:42
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/387; H04N1/40; H04N1/405; H04N1/4051; H04N1/4052
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
128 words
An image processing apparatus for converting a
basic image represented by multivalued data into a
binary image representing the basic image in pseudo
tones, and repeatedly printing the binary image on a
print medium, characterized by, comprising: binarizing means for sequentially comparing a
value of each pixel representing the basic image with a
predetermined threshold value, and performing
binarization on the pixel in accordance with the
comparison result; diffusing means for diffusing errors, generated in
the binarization, to neighboring pixels of a pixel of
interest by employing an error diffusion matrix having a
predetermined size; and incorporating means for incorporating, among the
errors diffused by said diffusing means, an error which
is outside the basic image into an area where said
binarizing means has not performed the binarization.
Claim 2
Dependent Claim
33 words
The apparatus according to claim 1, wherein said
incorporating means incorporates the error outside an
edge of the basic image into an edge opposite to said
edge, where binarization has not been performed.
Claim 3
Dependent Claim
61 words
The apparatus according to claim 1, further
comprising combining means for forming a combined image
by adjoining a supplemental image which is a part of the
basic image to the basic image, wherein the combined image is subjected to the
binarization performed by said binarizing means, error
diffusion performed by said diffusing means and error
incorporation performed by said incorporating means.
Claim 4
Dependent Claim
77 words
The apparatus according to claim 3, further
comprising correcting means for, upon incorporating the
error by said incorporating means, comparing an image
data value in a first area of the supplemental image
inclusive of a line adjacent to the basic image, with an
image data value in a second area of the basic image
corresponding to the first area, and correcting the
image data values of the first and second areas in
accordance with the comparison result.
Claim 5
Dependent Claim
98 words
The apparatus according to claim 4, wherein in a
case where the image data value in the first area
coincides with the image data value in the second area,
said correcting means utilizes said image data value as
a pseudo tone value without correction, and in a case
where the image data value in the first area does not
coincide with the image data value in the second area,
said correcting means utilizes, as the pseudo tone value,
a value corrected based on data values of neighboring
pixels of the pixel of interest represented by said
image data.
Claim 6
Dependent Claim
59 words
The apparatus according to claim 5, wherein said
correcting means comprises: weighted average means for calculating a weighted
average of the neighboring pixels; and correction value generating means for comparing
the multivalued data of the pixel of interest with the
weighted average calculated by said weighted average
means, and generating a correction value in accordance
with the comparison result.
Claim 7
Dependent Claim
20 words
The apparatus according to claim 3, further
comprising printing means for repeatedly printing the
binary image on a print medium.
Claim 8
Dependent Claim
28 words
The apparatus according to claim 7, wherein said
printing means includes an ink-jet printer having a
printhead which prints an image by discharging ink on
the print medium.
Claim 9
Dependent Claim
34 words
The apparatus according to claim 8, wherein said
printhead is a printhead for discharging ink by
utilizing heat energy, and includes heat energy
transducers for generating heat energy to be applied to
the ink.
Claim 10
Dependent Claim
29 words
The apparatus according to claim 8, wherein the
printhead is a color printhead which performs printing
in color by discharging cyan ink, magenta ink, yellow
ink or black ink.
Claim 11
Dependent Claim
19 words
The apparatus according to claim 8, wherein the
print medium, on which said ink-jet printer performs
printing, includes fabric.
Claim 12
Dependent Claim
63 words
The apparatus according to claim 7, wherein said
printing means prints the binary image on the print
medium such that the binary image is repeatedly printed
in horizontal and vertical directions, said combining means adjoins the supplemental
image to one edge of the basic image situated in
parallel to the horizontal direction, and said incorporating means incorporates the error in
the horizontal direction.
Claim 13
Dependent Claim
67 words
The apparatus according to claim 7, wherein said
printing means repeatedly prints the binary image on the
print medium while shifting the binary image in a
vertical direction by half the size of the binary image, said combining means adjoins the supplemental
image to one edge of the basic image situated parallel
to the vertical direction, and said incorporating means incorporates the error in
the vertical direction.
Claim 14
Dependent Claim
42 words
The apparatus according to claim 1, further
comprising: inputting means for inputting the basic image; and generating means for generating a multivalued
color image having R, G and B color components on the
basis of the data inputted by said inputting means.
Claim 15
Dependent Claim
124 words
An image processing method for converting a basic
image represented by multivalued data into a binary
image representing the basic image in pseudo tones, and
repeatedly printing the binary image on a print medium,
characterized by, comprising the steps of: sequentially comparing a value of each pixel
representing the basic image with a predetermined
threshold value, and performing binarization on the
pixel in accordance with the comparison result; diffusing errors, generated in the binarization,
to neighboring pixels of a pixel of interest by
employing an error diffusion matrix having a
predetermined size; and incorporating, among the errors diffused in said
diffusing step, an error which is outside the basic
image into an area where the binarization has not been
performed in said binarizing step.
Claim 16
Dependent Claim
35 words
The method according to claim 15, wherein in said
incorporating step, the error outside an edge of the
basic image is incorporated into an edge opposite to
said edge, where binarization has not been performed.
Claim 17
Dependent Claim
58 words
The method according to claim 15, further
comprising the step of forming a combined image by
adjoining a supplemental image which is a part of the
basic image to the basic image, wherein the combined image is subjected to the
binarization in said binarizing step, error diffusion in
said diffusing step and error incorporation in said
incorporating step.
Claim 18
Dependent Claim
77 words
The method according to claim 17, further
comprising the step of, upon incorporating the error in
said incorporating step, comparing an image data value
in a first area of the supplemental image inclusive of a
line adjacent to the basic image, with an image data
value in a second area of the basic image corresponding
to the first area, and correcting the image data values
of the first and second areas in accordance with the
comparison result.
Claim 19
Dependent Claim
59 words
An image processing apparatus or method wherein image
data is processed using an error diffusion process and
wherein an error from outside the area of the image data
being processed, for example an error obtained from a repeat
or copy of part of the image area being processed, is
incorporated into the errors used in the error diffusion
process.
Claim 20
Dependent Claim
20 words
An image processing apparatus or method having the
features recited in any one or any combination of the
preceding claims.
References Cited (Backward Citations)
No citation records indexed.
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