Patent EP1011064A2 successfully refreshed from Google Patents.
EP1011064A2
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EP
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Image pattern detection method and apparatus
Assignee: Canon Inc
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Filing: 1999-11-30
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Granted: —
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Expires: 2019-11-30
Abstract
Abstract Disclosed is method of detecting a predetermined mark (30) forming part of an image. A digitized form (48, 49) of the image (21) comprising a plurality of picture elements is provided and within a current region of the image a set of features is determined. The features typically comprise a dominant colour feature (44) within the current region; and at least one moment feature (111) based on picture elements pertaining to the predetermined mark within the current region. Each determined feature is compared (113) with a corresponding predetermined feature (114) of the predetermined mark. Using the comparison, a confidence level for a detection of said predetermined mark within the current region calculated. Based on the confidence level, whether or not said predetermined mark is detected in the current region can then be determined. Adjunct to the above method, also disclosed are methods for providing multiple encoded representations (40) of the image, detecting a centre location (108, 160) of a predetermined pattern in the image, and determining (170, 171) a moment feature of a portion of the image.
Inventors
- 👤 Kai Huang
- 👤 Yu-Ling Chen
- 👤 Peter Leslie Bell
- 👤 Michael John Webb
- 👤 Yoong-Chert Foo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 15:33
CPC Classifications
G; G06; G06V; G06V10/00; G06V10/40; G06V10/44
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
131 words
A method of detecting a predetermined mark forming part of an image, the
method comprising the steps of: (a) receiving a digitized form of the image comprising a plurality
of picture elements; (b) determining within a current region of said image a set of features
comprising at least: (i) a dominant colour feature within the current region; and (ii) at least one moment feature based on picture elements pertaining
to the predetermined mark within the current region; and (c) comparing each determined feature with a corresponding predetermined
feature of said predetermined mark; (d) calculating, using the comparison, a confidence level for a detection of
said predetermined mark within said current region; and (e) determining, based on the confidence level, whether or not said
predetermined mark is detected in the current region.
Claim 2
Dependent Claim
32 words
A method of claim 1, wherein the step of determining the set of features further
comprises determining a number of picture elements within said current region not
pertaining to the predetermined mark.
Claim 3
Dependent Claim
19 words
A method according to claim 1, wherein said comparing comprises thresholding
each determined feature using a predetermined threshold value.
Claim 4
Dependent Claim
28 words
A method according to claim 3, wherein the identified set of features comprises a
range of feature values for each said feature and the corresponding predetermined
threshold value.
Claim 5
Dependent Claim
33 words
A method according to claim 1, further comprising the step of: (f) selecting a new region of the image as said current region and repeating
steps (b) to (e) on the new region.
Claim 6
Dependent Claim
158 words
Apparatus for detecting a predetermined mark forming part of an image, the
image comprising a plurality of pixels and said mark being distinguishable by a specified
pixel arrangement of predetermined colours, the apparatus comprising: input means for providing a region of the image; feature determining means for determining within a current region of said image
a set of features comprising at least: (i) a dominant colour feature within the current region; and (ii) at least one moment feature based on the pixels having one of the
predetermined colours of the current region; and comparison means for comparing each said determined feature with a
corresponding predetermined feature of said predetermined mark; calculator means for calculating, using an output of said comparison means, a
confidence value for a detection of said predetermined mark within said current region;
and mark determining means for determining based on the confidence value whether
or not said predetermined mark is detected in the current region.
Claim 7
Dependent Claim
27 words
Apparatus according to claim 6, wherein the feature determining means further
determines a total number of pixels having one of the predetermined colours of the
current region.
Claim 8
Dependent Claim
160 words
A computer readable medium, having a program recorded thereon, where the
program is configured to make a computer execute a procedure to detect a predetermined
mark forming part of an image, the image comprising a plurality of pixels and said mark
being distinguishable by a specified pixel arrangement of predetermined colours, the
program comprising: code for determining within a current region of said image in a
digitized form a set of features comprising at least: i) a dominant colour feature within the current region; and ii) at least one moment feature based on picture elements pertaining
to the predetermined mark within the current region; code for comparing each determined feature with a corresponding predetermined
feature of said predetermined mark; code for calculating, using the comparison, a confidence level for a detection of
said predetermined mark within said current region; and code for determining, based on the confidence level, whether or not said
predetermined mark is detected in the current region.
Claim 9
Dependent Claim
35 words
A medium according to claim 8, wherein the code for determining the set of
features further comprises code for determining a number of picture elements within said
current region not pertaining to the predetermined mark.
Claim 10
Dependent Claim
23 words
A medium according to claim 8, wherein said code for comparing comprises
code for thresholding each determined feature using a predetermined threshold value.
Claim 11
Dependent Claim
34 words
A medium according to claim 8 wherein said code for determining said set of
features comprises code for determining a total number of pixels having one of the
predetermined colours of said current region.
Claim 12
Dependent Claim
137 words
A computer program element comprising computer program code means to
make a computer execute a procedure to detect a predetermined mark forming part of an
image, the code means comprising: code for determining within a current region of said image in a
digitized form a set of features comprising at least: (i) a dominant colour feature within the current region; and (ii) at least one moment feature based on picture elements pertaining
to the predetermined mark within the current region; and code for comparing each determined feature with a corresponding predetermined
feature of said predetermined mark; code for calculating, using the comparison, a confidence level for a detection of
said predetermined mark within said current region; and code for determining, based on the confidence level, whether or not said
predetermined mark is detected in the current region.
Claim 13
Dependent Claim
189 words
Apparatus for providing multiple encoded representations of an image, said
image comprising a plurality of pixels, each pixel being represented in multiple colour
channels, said apparatus comprising: pixel buffer pipe means having an input means for receiving a plurality of pixels
of said image data in a predetermined order; threshold determining means for dynamically determining a threshold value
based on the pixel values in the pixel buffer pipe means; threshold buffer means for receiving and thresholding each pixel output from
said pixel buffer pipe means against said dynamic determined threshold value to
determine whether each said output pixel is a foreground pixel or a background pixel, said
threshold buffer means outputting an encoded representation comprising either: (a) a background code symbol if the pixel is a background pixel; or (b) a colour code symbol representing a colour value of the pixel if the
pixel is a foreground pixel; binarisation means for producing a bitmap representation from said encoded
representation; and subsampling means for subsampling said encoded representation in accordance
with said background and colour code symbols of the encoded representation to provide a
desired resolution of the encoded representation.
Claim 14
Dependent Claim
49 words
Apparatus according to claim 13, wherein said apparatus further comprises
subsample control means for generating control signals provided to said pixel buffer pipe
means for further subsampling the input image data according to at least one of a
magnification value, an input resolution value and a desired intermediate resolution.
Claim 15
Dependent Claim
24 words
Apparatus according to claim 13, wherein said threshold determining means
dynamically determines a threshold value from predetermined pixels of said pixel buffer
pipe means.
Claim 16
Dependent Claim
14 words
Apparatus according to claim 13, wherein said predetermined pixels comprise
lead and lag pixels.
Claim 17
Dependent Claim
37 words
Apparatus according to claim 13, wherein said background code symbol is zero
(0) and the colour code symbol is a number from one (1) to P, P being a maximum
number of possible foreground colour pixel values.
Claim 18
Independent Claim
162 words
A method of providing multiple encoded representations of an image, said image
comprising a plurality of pixels, each pixel being represented in multiple colour channels,
said method comprising step of: providing a plurality of pixels of said image data in a predetermined order; determining a dynamic threshold value based on the provides pixel values; thresholding each pixel of against said dynamically determined threshold to
determine whether each said pixel is a foreground or a background pixel and outputting
an encoded representation comprising either: a) a background code symbol if the pixel is a background pixel; or b) a colour code symbol representing a colour value of the pixel if
the pixel is a foreground pixel; producing a binary bitmap representation at a first desired resolution from said
encoded representation the image; and subsampling said encoded representation in accordance with said background
and colour code symbols of the encoded representation to provide a second desired
resolution of the encoded representation of the image.
Claim 19
Dependent Claim
87 words
A method according to claim 18, wherein said subsampling comprises
reproducing for m code symbols: (i) n colour code symbols of a most frequently occurring colour code
symbol of the m code symbols; (ii) n colour code symbols of a selected colour code (symbol) which is one
of those equally most frequently occurring colour code symbol of the m code symbols; or (iii) n background code symbols when substantially all m code symbols are
background code symbols; m and n being integers with n < m .
Claim 20
Dependent Claim
38 words
A method according to claim 19, wherein said background code symbol is zero
(0) and the colour code symbol is a number from one (1) to P, P being a maximum
number of possible foreground (pixel) colour values.
Claim 21
Dependent Claim
84 words
A method according to claim 18, wherein said subsampling comprises outputting
for a predetermined number of code symbols: (i) a colour code symbol of a most frequently occurring colour code
symbol of the predetermined number code symbols; (ii) a colour code symbol of a selected colour code symbol which is one of
those equally most frequently occurring colour code symbols of the predetermined
number code symbols; or (iii) a background code symbol when substantially all the predetermined
number code symbols are background code symbols.
Claim 22
Dependent Claim
38 words
A method according to claim 21, wherein said background code symbol is zero
(0) and the colour code symbol is a number from one (1) to P, P being a maximum
number of possible foreground (pixel) colour values.
Claim 23
Dependent Claim
210 words
A computer program element comprising computer program code means to
make a computer execute a procedure to provide multiple encoded representations of an
image, said image comprising a plurality of pixels, each pixel being represented in
multiple colour channels, the code means comprising: pixel buffer pipe code means having an input code means for receiving a
plurality of pixels of said image data in a predetermined order; threshold determining code means for dynamically determining a threshold value
based on the pixel values in the pixel buffer pipe code means; a threshold buffer code means for receiving and thresholding each pixel of
output from the pixel buffer pipe code means against said dynamically determined
threshold value to determine whether each said output pixel is a foreground or a
background pixel and outputting an encoded representation comprising: (a) a background code symbol if the pixel is a background pixel; or (b) a colour code symbol representing a colour value of the pixel if the
pixel is a foreground pixel; binarisation code means for producing a bitmap representation from said
encoded representation; and subsampling code means for subsampling said encoded representation in
accordance with said background and colour code symbols of the encoded representation
to provide a desired resolution of the encoded representation.
Claim 24
Dependent Claim
55 words
A computer program element according to claim 23, wherein said code means
further comprises subsample control code means for generating control signals to enable
the pixel buffer pipe code means to further subsample the input image data according to at
least one of a magnification value, an input resolution value and a desired intermediate
resolution.
Claim 25
Dependent Claim
29 words
A computer program element according to claim 23, wherein said threshold
determining code means dynamically determines a threshold value from predetermined
pixels of the pixel buffer pipe code means.
Claim 26
Independent Claim
145 words
A method for detecting a centre location of a predetermined pattern in an image,
said method comprising the steps of: (a) examining a plurality of pixel values at predetermined pixel locations
within said image, said examined locations being determined by a plurality of groups
comprising multiple locations in each group and said groups being configured into a
predetermined geometric arrangement having a corresponding geometric centre location; (b) determining an evidence value for each said group of examined pixel
values; (c) determining a deviation measure value from the evidence values of
substantially all said groups of said geometric arrangement; and (d) thresholding the deviation measure value against a predetermined
threshold value and outputting either: (i) a centre value, indicating a pixel location corresponding to the
centre location, if the deviation value for each group is below the predetermined
threshold value; or (ii) an invalid value otherwise.
Claim 27
Dependent Claim
30 words
A method according to claim 26, wherein said geometric arrangement is applied
repetitively across said image and steps (a) to (d) are repeated at each application of said
geometric arrangement.
Claim 28
Dependent Claim
19 words
A method according to claim 26, wherein for each centre value outputted a
corresponding deviation value is also outputted.
Claim 29
Dependent Claim
32 words
A method according to claim 28, further comprising determining a true centre
value for the pattern by selecting in a predetermined neighbourhood region, a centre value
having a minimum corresponding deviation value.
Claim 30
Dependent Claim
20 words
A method according to claim 26, wherein each group comprises an n row by m
column array of pixel locations.
Claim 31
Dependent Claim
21 words
A method according to claim 30, wherein said arrays are geometrically arranged
at a fixed radius relative to said centre location.
Claim 32
Dependent Claim
147 words
Apparatus for detecting a centre location of a predetermined pattern in an image
comprising: examining means for examining a plurality of pixel values at predetermined
pixel locations of said image, said examined locations being determined by a plurality of
groups comprising multiple locations in each group, said groups being configured into a
predetermined geometric arrangement having a corresponding geometric centre location; evidence value determining means for determining an evidence value for each
said group of examined pixel values; deviation measure determining means for determining a deviation measure value
from the evidence values of substantially all groups of the arrangement; and output means for thresholding the deviation value against a predetermined
threshold value and outputting either: (i) a centre value, indicating a pixel location corresponding to the
centre location, if the deviation value for each group is below the predetermined
threshold value; or (ii) an invalid value otherwise.
Claim 33
Dependent Claim
19 words
Apparatus according to claim 32, wherein each group is an n row by m column
array of pixel locations.
Claim 34
Dependent Claim
20 words
Apparatus according to claim 33, wherein said arrays are geometrically arranged
at a fixed radius relative to said centre location.
Claim 35
Dependent Claim
165 words
A computer program element comprising computer program code means to
make a computer execute a procedure to detect a centre location of a predetermined
pattern in an image, code means comprising: examining code means for examining a plurality of pixel values at predetermined
pixel locations, said examined locations being determined by a plurality of groups
comprising multiple locations in each group, said groups being configured into a
predetermined geometric arrangement having a corresponding geometric centre location; evidence value determining code means for determining an evidence value for
each said group of examined pixel values; deviation measure determining code means for determining a deviation measure
value from the evidence values of substantially all groups of the arrangement; and output code means for thresholding the deviation value against a predetermined
threshold value and outputting either: (i) a centre value, indicating a pixel location corresponding to the
centre location, if the deviation value for each group is below the predetermined
threshold value; or (ii) an invalid value otherwise.
Claim 36
Dependent Claim
22 words
A computer program element according to claim 35, wherein each group
comprises an n row by m column array of pixel locations.
Claim 37
Dependent Claim
23 words
A computer program element according to claim 36, wherein said arrays are
geometrically arranged at a fixed radius relative to said centre location.
Claim 38
Independent Claim
115 words
A method of determining a moment feature of a portion of an image, said image
portion comprising a plurality of pixel values, said method comprising the steps of: storing a predetermined subset of coefficient values of a moment matrix, said
moment matrix having a predetermined symmetry and said subset being those coefficient
values which exploit at least part of said symmetry; combining pixel values at selected pixel locations in said image portion to
provide a combined result, wherein said selected locations are associated with a
respective coefficient value of said subset; multiplying each combined result with a corresponding coefficient value; and accumulating each multiplied combined result to determine a moment feature for
said image portion.
Claim 39
Dependent Claim
33 words
A method according to claim 38 wherein the moment feature of the portion of
the image is compared to a known moment feature of a specified image pattern to produce
a comparison result.
Claim 40
Dependent Claim
30 words
A method according to claim 39 wherein the comparison result is used to
determined whether or not a match is detected between the portion of image and the
specified image.
Claim 41
Dependent Claim
21 words
A method according to claim 38, wherein each of said pixel values in a binary
representation of either on or off.
Claim 42
Dependent Claim
140 words
Apparatus for determining a moment feature of a portion of image, said image
portion comprising a plurality of pixel values, said apparatus comprising; memory storage means for storing a predetermined subset of coefficient values
of a moment matrix, said moment matrix having a predetermined symmetry and said
subset being those coefficient values which exploit at least part of said symmetry; a plurality of accumulator means, each said accumulator means having input
means for receiving and combining pixel values at selected pixel locations in said image
portion to provide a combined result, wherein said selected locations are associated with a
respective coefficient value of said subset; a plurality of multiplier means for respectively multiplying each combined result
with a corresponding coefficient value; and result accumulator means for accumulating each multiplied combined result to
determine a moment feature for said image portion.
Claim 43
Dependent Claim
49 words
Apparatus according to claim 42, further comprising comparator means for
comparing the moment feature of the portion of the image to a known moment feature of
a specified image pattern and for determining whether or not a match is detected between
the portion of image and the specified image.
Claim 44
Dependent Claim
148 words
A computer program element comprising computer program code means to
make a computer execute a procedure to determine a moment feature of a portion of an
image, said image portion comprising a plurality of pixel values, with reference
to a predetermined subset of coefficient values of a moment matrix, said
moment matrix having a predetermined symmetry and said subset being those
coefficient values which exploit at least part of said symmetry, the code
means comprising: accumulator code means having input code means for receiving and combining
pixel values at selected pixel locations in said image portion to provide a combined result,
wherein said selected locations are associated with a respective coefficient value of said
subset; multiplier code means for multiplying each combined result with a
corresponding coefficient value; and result accumulator code means for accumulating each multiplied combined result
to determine a moment feature for said image portion.
Claim 45
Dependent Claim
52 words
A computer program element according to claim 44, further comprising
comparator code means for comparing the moment feature of the portion of the image to a
known moment feature of a specified image pattern and determined whether or not a
match is detected between the portion of image and the specified image.
Claim 46
Dependent Claim
19 words
A computer program element according to any of
claims 12, 23, 35 and 44 when embodied as a signal.
References Cited (Backward Citations)
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