EP0849940A2
Expired / Lapsed
EP
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An apparatus for converting gray levels of an image, a method thereof, a program storage device thereof, and an infrared camera
Assignee: Fujitsu Ltd
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Filing: 1997-07-09
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Granted: —
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Expires: 2017-07-09
Abstract
Abstract An apparatus for converting gray levels of an image, a method thereof, a program storage device thereof, and an infrared camera. The object of the present invention is to provide an apparatus for converting gray levels into fewer gray levels without missing a local gradation, a method thereof, a program storage device thereof, and an infrared camera to which the present invention is applied. A positive mask image (C) and a reversed mask image (C') are obtained the edge detected image (B) which is produced by emphasizing edges of an original image (A). A low frequency component (D) is obtained by performing an edge preserving smoothing operation for A masked with C, and performing a non-edge preserving smoothing operation for A masked with C'. A high frequency component (E) is obtained by calculating of (A - D). After D is compressed to D' and E is emphasized to E', an output image (F') is obtained by adding D' and E'.
Inventors
- 👤 Morito Shiohara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:44
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/20
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
87 words
A gray level converting apparatus comprising: a means for dividing an original image
with multiple gray levels into a low frequency component
which represents a broad gradation and a high frequency
component which represents a local gradation; a means for detecting an edge strength
which is defined as the difference of the gray levels
between neighbouring pixels of the original image; and a means for changing a dividing
characteristic used in said dividing means in accordance
with the edge strength determined by said edge strength
detecting means.
Claim 2
Dependent Claim
53 words
A gray level converting apparatus of claim 1,
wherein further comprising: a means for compressing the gray levels of
the low frequency component divided by said dividing
means; and a means for composing the compressed low
frequency component compressed by said compressing means
with the high frequency component divided by said
dividing means.
Claim 3
Dependent Claim
95 words
A gray level converting apparatus of claim 1 or
2, wherein, said characteristic changing means changes
a characteristic for extracting the low frequency
component in accordance with the edge strength determined
by said edge strength detecting means, and said dividing means comprising: a means for extracting the low frequency
component from the original image using the low frequency
component extracting characteristic changed by said
characteristic changing means; and a means for extracting the high frequency
component in accordance with the original image and the
low frequency component extracted by said low frequency
component extracting means.
Claim 4
Dependent Claim
101 words
A gray level converting apparatus of claim 1,
wherein said characteristic changing means comprising: an edge extracting means for extracting
pixels which are contained within a fixed number of the
pixels on both sides of the edges detected said edge
strength detecting means from the original image; and a non-edge extracting means for extracting
pixels except the pixels extracted by said edge
extracting means, and said dividing means extracts the low-frequency
component using an edge preserving smoothing
operation for pixels extracted by said edge extracting
means and using a non-edge preserving smoothing operation
for pixels extracted by said non-edge extracting means.
Claim 5
Dependent Claim
44 words
A gray level converting apparatus of claim 4,
wherein said low frequency component extracting means
makes the size of a filter which is applied for
extracting the low frequency component smaller as the
edge strength detected by said edge strength detecting
means becomes larger.
Claim 6
Dependent Claim
105 words
A gray level converting apparatus of claim 1,
wherein said low frequency component extracting means
comprising: a means for extracting pixels which are
included within a fixed number of pixels on the both
sides of the edges detected by said edge strength
detecting means; and a means for extracting pixels except the
pixels extracted said edge pixel extracting means; and said dividing means extracts the low
frequency component using a filter with a relatively
small size for pixels extracted by said edge extracting
means, and using a filter with the size larger than the
relatively small size for pixels extracted by said non-edge
extracting means.
Claim 7
Dependent Claim
86 words
An infrared camera comprising: a means for dividing an original image
with multi gray levels into a low frequency component
which represents a broad gradation and a high frequency
component which represents a local gradation; a means for compressing the low frequency
component to less gray levels; a means for emphasizing the high frequency
component divided by said dividing means; and a means for composing the compressed low
frequency component compressed by said compressing means
and the emphasized high frequency component emphasized by
said emphasizing means.
Claim 8
Dependent Claim
81 words
A gray level converting method comprising the
steps of: dividing an original image with multi gray
levels into a low frequency component which represents a
broad gradation and a high frequency component which
represents a local gradation; detecting an edge strength which is
defined as the difference of the gray level between
neighbouring pixels of the original image; and changing a dividing characteristic used at
said dividing step in accordance with the edge strength
determined at said edge strength detecting step.
Claim 9
Dependent Claim
50 words
A gray level converting method of claim 8,
wherein further comprising the steps of: compressing the gray levels of the low
frequency component divided at said dividing step; and composing the compressed low frequency
component compressed at said compressing step with the
high frequency component divided at said dividing step.
Claim 10
Dependent Claim
92 words
A gray level converting method of claim 8 or 9,
wherein, said characteristic changing step changes
a characteristic for extracting the low frequency
component in accordance with the edge strength determined
at said edge strength detecting step, and said dividing step comprising the steps
of: extracting the low frequency component
from the original image using the low frequency component
extracting characteristic changed at said characteristic
changing step; and extracting the high frequency component in
accordance with the original image and the low frequency
component extracted at said low frequency component
extracting step.
Claim 11
Dependent Claim
106 words
A gray level converting method of claim 8,
wherein said characteristic changing step comprises the
steps of: an edge extracting step for extracting
pixels which are contained within a fixed number of the
pixels on both sides of the edges detected at said edge
strength detecting step from the original image; and a non-edge extracting step for extracting
pixels except the pixels extracted at said edge
extracting step, and said dividing step extracts the low
frequency component using an edge preserving smoothing
operation for pixels extracted at said edge extracting
step and using a non-edge preserving smoothing operation
for pixels extracted at said non-edge extracting step.
Claim 12
Dependent Claim
44 words
A gray level converting method of claim 11,
wherein said low frequency component extracting step
makes the size of a filter which is applied for
extracting the low frequency component smaller as the
edge strength detected at said edge strength detecting
step becomes larger.
Claim 13
Dependent Claim
105 words
A gray level converting method of claim 8,
wherein said low frequency component extracting step
comprises the steps of: extracting pixels which are included
within a fixed number of pixels on the both sides of the
edges detected at said edge strength detecting step; and extracting pixels except the pixels
extracted at said edge pixel extracting step, and said dividing step extracts the low
frequency component using a filter with a relatively
small size for pixels extracted at said edge pixel
extracting step, and using a filter with the size larger
than the relatively small size for pixels extracted at
said non-edge pixel extracting step.
Claim 14
Dependent Claim
29 words
A program storage device readable by a machine,
tangibly embodying a program of instructions executable
by the machine to perform one of the methods of claim 8
to 13.
References Cited (Backward Citations)
No citation records indexed.
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