Patent EP0912047A2 successfully refreshed from Google Patents.
EP0912047A2
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EP
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Imaging apparatus comprising means for expanding the dynamic range
Assignee: Olympus Corp
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Filing: 1998-10-22
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Granted: —
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Expires: 2018-10-22
Abstract
Abstract An object is imaged continuously during a first exposure time and a second exposure time shorter than the first exposure time. Weights one of which decreases monotonously and the other of which increases monotonously are applied to first and second resultant image signals under the condition that the sum of the weights is 1. The first and second image signals that have been weighted are added up, thus producing a synthetic picture signal. When a luminance level is low, the ratio of the first image signal, which has been produced during the longer exposure time, to the second image signal is increased. This results in an image demonstrating a high signal-to-noise ratio. When the luminance level is high, the ratio of the second image signal, which has been produced during the shorter exposure time, to the first image signal is increased. This results in a synthetic image that proves a wide dynamic range, depicts a smoothly varying brightness level, and exhibits a characteristic of being seen almost natural. Moreover, the first and second image signals are produced to resemble those produced during mutually different exposure times by controlling an amount of light incident on an imaging device or by varying an amount of illumination light.
Inventors
- 👤 Kanichi Matsumoto
- 👤 Katsuyuki Saito
- 👤 Kotaro Ogasawara
- 👤 Kuniaki Kami
- 👤 Shinji Yamashita
- 👤 Noboru Kusamura
- 👤 Akihiko Mochida
- 👤 Wataru Ohno
- 👤 Makoto Tsunakawa
- 👤 Hideki Tashiro
- 👤 Manabu Yajima
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 11:49
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/50; H04N23/555; H04N25/00; H04N25/40; H04N25/42; H04N23/45; H04N23/70; H04N23/74; H04N25/50; H04N25/57; H04N25/58; H04N25/587; H04N25/589; H04N25/70; H04N25/71
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
183 words
An imaging apparatus, comprising: an imaging means for successively outputting a first
image signal produced by imaging an object during a first
exposure time and a second image signal produced by
imaging said object during a time shorter than said first
exposure time; an image signal producing means composed of: first
and second weighting circuits for applying a first weight,
which decreases monotonously with an increase in light
level up to a light level causing said first and second
image signals to have a saturation value, and a second
weight, which increases monotonously therewith, to said
first and second image signals under the condition that
the sum of said first and second weights is 1; and an
adding circuit for adding up first and second picture
signals produced by applying said first and second weights
to said first and second image signals by means of said
first and second weighting circuits; and a signal processing means for processing a picture
signal output from said adding circuit and producing a
video signal according to which an image can be displayed
on a display means.
Claim 2
Dependent Claim
26 words
An imaging apparatus according to claim 1,
further comprising an exposure time setting means for
varying at least one of said first and second exposure
times.
Claim 3
Dependent Claim
29 words
An imaging apparatus according to claim 2,
wherein said exposure time setting means uses a waveform-detected
signal produced by detecting the waveform of said
first or second image signal.
Claim 4
Dependent Claim
185 words
An imaging apparatus, comprising: an imaging means for successively outputting a first
image signal produced by imaging an object during a first
exposure time, and a second image signal that has a
saturation value relative to a higher light level than
said first image signal; a picture signal producing means composed of: first
and second weighting circuits for applying a first weight,
which decreases monotonously with an increase in light
level up to a light level causing said first and second
image signals to have a saturation value, and a second
weight, which increases monotonously therewith, to said
first and second image signals under the condition that
the sum of said first and second weights is 1; and an
adding circuit for adding up first and second picture
signals produced by applying said first and second weights
to said first and second image signals by means of said
first and second weighting circuits; and a signal processing means for processing a picture
signal output from said adding circuit and producing a
video signal according to which an image can be displayed
on a display means.
Claim 5
Dependent Claim
50 words
An imaging apparatus according to claim 4,
wherein said imaging means images an object during a
second exposure time that is shorter than said first
exposure time, and thus outputs said second image signal
that has the saturation value relative to a higher light
level than said first image signal.
Claim 6
Dependent Claim
71 words
An imaging apparatus according to claim 4,
wherein during a second exposure time during which said
second image signal is produced, an amount of light coming
from said object and falling on said imaging means through
an imaging window is restricted by an amount-of-light
restricting means, and said imaging means outputs said
second image signal that has the saturation value relative
to a higher light level than said first image signal.
Claim 7
Dependent Claim
80 words
An imaging apparatus according to claim 4,
wherein said weights applied by said picture signal
producing means are such that: when a light level is much
lower than the light level causing said first image signal
to have the saturation value, said first weight is larger
than said second weight; and when the light level is
higher than the light level causing said first image
signal to have the saturation value, said second weight is
larger than said first weight.
Claim 8
Dependent Claim
39 words
An imaging apparatus according to claim 4,
wherein said first weight function F1(x) is cos 2 (px) where
x is a light level and p is a coefficient, and said second
weight function F2(x) is sin 2 (px) .
Claim 9
Dependent Claim
26 words
An imaging apparatus according to claim 8,
wherein said coefficient p satisfies p≒π/(2s) where s is a
light level of light incident on said imaging means.
Claim 10
Dependent Claim
24 words
An imaging apparatus according to claim 4,
wherein said imaging means includes a progressive imaging
device having two systems of horizontal transfer output
circuits.
Claim 11
Dependent Claim
20 words
An imaging apparatus according to claim 10,
wherein said signal processing means produces a video
signal conformable to the interlacing.
Claim 12
Dependent Claim
48 words
An imaging apparatus according to claim 4,
wherein said image signal producing means includes a
weight data storage means that stores data of said first
weight to be applied to said first image signal and data
of said second weight to be applied to said second image
signal.
Claim 13
Dependent Claim
45 words
An imaging apparatus according to claim 12,
wherein said weight data storage means stores data of a
weight to be applied to said first image signal and data
of a weight to be applied to said second image signal, and
the weights exhibit different characteristics.
Claim 14
Dependent Claim
69 words
An imaging apparatus according to claim 13,
further comprising a brightness detecting means for
detecting brightness information of an object in an output
signal of said imaging means, wherein a weight to be
applied to said first image signal and a weight to be
applied to said second image signal are selected based on
the brightness information of an object, and thus read
from said weight data storage means.
Claim 15
Dependent Claim
29 words
An imaging apparatus according to claim 5,
wherein said imaging means images said object during said
first exposure time, and produces said first image signal
and second image signal.
Claim 16
Dependent Claim
55 words
An imaging apparatus according to claim 4,
wherein said picture signal producing means produces a
synthetic picture signal exhibiting such a characteristic
that a differential coefficient thereof relative to a
light level varies continuously with an increase in light
level up to a light level causing said second image signal
to have the saturation value.
Claim 17
Dependent Claim
18 words
An imaging apparatus according to claim 16,
wherein the differential coefficient decreases
monotonously relative to the light level.
Claim 18
Dependent Claim
237 words
An endoscopic imaging apparatus, comprising: an endoscope having an elongated insertion unit,
irradiating illumination light to an object through an
illumination window located at the distal end of said
insertion unit, and including an imaging means for
successively outputting a first image signal produced by
imaging said object illuminated with said illumination
light during a first exposure time, and a second image
signal that has a saturation value relative to a higher
light level than said first image signal; an image signal producing means composed of: first
and second weighting circuits for applying a first weight,
which decreases monotonously with an increase in light
level up to a light level causing said first and second
image signals to have the saturation value, and a second
weight, which increases monotonously therewith, to said
first and second image signals under the condition that
the sum of said first and second weights is 1; and an
adding circuit for adding up first and second picture
signals produced by applying said first and second weights
to said first and second image signals by means of said
first and second weighting circuits; a signal processing means for processing a picture
signal output from said adding circuit and producing a
video signal according to which an image can be displayed
on a display means; and a display means for displaying a synthetic image
represented by said picture signal when inputting said
video signal.
Claim 19
Dependent Claim
51 words
An endoscopic imaging apparatus according to claim
18, wherein said imaging means images said object during a
second exposure time that is shorter than said first
exposure time, and thus outputs said second image signal
that has the saturation level relative to a higher light
value than said first image signal.
Claim 20
Dependent Claim
72 words
An endoscopic imaging apparatus according to claim
18, wherein during a second exposure time during which
said second image signal is produced, an amount of light
coming from said object and falling on said imaging means
through an imaging window is restricted by an amount-of-light
restricting means, and said imaging means outputs
said second image signal that has the saturation value
relative to a higher light level than said first image
signal.
Claim 21
Dependent Claim
43 words
An endoscopic imaging apparatus according to claim
18, further comprising a light source unit for supplying
illumination light to a light guide that runs through said
insertion unit of said endoscope, propagates illumination
light, and emits the illumination light through said
illumination window.
Claim 22
Dependent Claim
69 words
An endoscopic imaging apparatus according to claim
21, wherein during a second exposure time during which
said imaging means produces said second image signal, said
light source unit allows an amount-of-light restricting
means to restrict illumination light to be supplied to
said light guide, and said imaging means outputs said
second image signal that has the saturation value relative
to a higher light level than said first image signal.
Claim 23
Dependent Claim
34 words
An endoscopic imaging apparatus according to claim
22, wherein said amount-of-light restricting means is a
light restriction filter for restricting illumination
light generated by a lamp and supplying resultant light to
said light guide.
Claim 24
Dependent Claim
23 words
An endoscopic imaging apparatus according to claim
22, wherein said amount-of-light restricting means
restricts an amount of illumination light generated by a
lamp.
Claim 25
Dependent Claim
56 words
An endoscopic imaging apparatus according to claim
18, wherein said endoscope is an electronic endoscope
having an imaging device, which is included in said
imaging means and provided with the ability to
photoelectrically convert a signal, placed on the image
plane of an objective optical system located at the distal
end of said elongated insertion unit.
Claim 26
Dependent Claim
89 words
An endoscopic imaging apparatus according to claim
18, wherein said endoscope is a TV camera-mounted
endoscope composed of an optical endoscope having an image
propagating means for propagating an object image formed
by an objective optical system located at the distal end
of said elongated insertion unit to an optical system, and
a TV camera that is mounted on an eyepiece of said optical
endoscope and has an imaging device, which is included in
said imaging means and provided with the ability to
photoelectrically convert a signal, incorporated therein.
Claim 27
Dependent Claim
53 words
An endoscopic imaging apparatus according to claim
18, wherein said endoscope includes a common image
formation optical system, and said imaging means is
composed of a plurality of imaging devices located at
positions respectively at which a plurality of images are
formed through a plurality of apertures by said image
formation optical system.
Claim 28
Dependent Claim
32 words
An endoscopic imaging apparatus according to claim
19, wherein said imaging means images said object during
said first exposure time so as to produce said first image
signal and second image signal.
Claim 29
Dependent Claim
31 words
An endoscopic imaging apparatus according to claim
18, wherein said imaging device included in said imaging
means has a color separation filter used to achieve color
imaging under white illumination light.
Claim 30
Dependent Claim
45 words
An endoscopic imaging apparatus according to claim
18, wherein said imaging means is a field-sequential
imaging means that includes a monochrome imaging device
not having a color separation filter, and that carries out
color imaging under illumination of field-sequential light
having a plurality of wavelengths.
Claim 31
Dependent Claim
205 words
An imaging apparatus, comprising: an imaging means for successively outputting a first
image signal produced by imaging an object during a first
exposure time, and a second image signal that is produced
by imaging said object during a second exposure time
shorter than said first exposure time and that has a
saturation value relative to a higher light level than
said first image signal; a picture signal producing means composed of: first
and second weighting circuits for applying a first weight,
which decreases monotonously with an increase in light
level up to a light level causing said first and second
image signals to have the saturation value, and a second
weight, which increases monotonously therewith, to said
first and second image signals under the condition that
the sum of said first and second weights is about 1; and
an adding circuit for adding up first and second picture
signals produced by applying said first and second weights
to said first and second image signals by means of said
first and second weighting circuits; and a signal processing means for processing a picture
signal output from said adding circuit and producing a
video signal according to which an image can be displayed
on a display means.
Claim 32
Dependent Claim
186 words
An imaging apparatus, comprising: an imaging means for successively outputting a first
image signal produced by imaging an object during a first
exposure time, and a second image signal that has a
saturation value relative to a higher light level than
said first image signal; a picture signal producing means composed of: first
and second weighting circuits for applying a first weight,
which decreases monotonously with an increase in light
level up to a light level causing said first and second
image signals to have the saturation value, and a second
weight, which increases monotonously therewith, to said
first and second image signals under the condition that
the sum of said first and second weights is about 1; and
an adding circuit for adding up first and second picture
signals produced by applying said first and second weights
to said first and second image signals by means of said
first and second weighting circuits; and a signal processing means for processing a picture
signal output from said adding circuit and producing a
video signal according to which an image can be displayed
on a display means.
Claim 33
Dependent Claim
207 words
An imaging apparatus, comprising: an imaging means for successively outputting a first
image signal produced by imaging an object during a first
exposure time, and a second image signal that has a
saturation value relative to a higher light level than
said first image signal; a picture signal producing means composed of: first
and second weighting circuits for applying a first weight,
which decreases monotonously with an increase in light
level up to a light level causing said first and second
image signals to have the saturation value, and a second
weight, which increases monotonously therewith, to said
first and second image signals in relation to any of light
levels ranging to the light level, which causes at least
said first image signal to have the saturation value,
under the condition that the sum of said first and second
weights remains constant; and an adding circuit for adding
up picture signals produced by applying said first and
second weights to said first and second image signals by
means of said first and second weighting circuits; and a signal processing means for processing a picture
signal output from said adding circuit and producing a
video signal according to which an image can be displayed
on a display means.
Claim 34
Dependent Claim
38 words
An imaging apparatus according to claim 33,
wherein when a light level is higher than the light level
causing said first image signal to have the saturation
value, said first weighting circuit outputs a weight
coefficient of 0.
Claim 35
Dependent Claim
51 words
An imaging apparatus according to claim 33,
wherein when a light level is higher than the light level
causing said first image signal to have the saturation
value, said picture signal is determined substantially
with a weight coefficient that is applied to said second
image signal by said second weighting circuit.
References Cited (Backward Citations)
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