EP0912047B1
Expired / Lapsed
EP
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Imaging apparatus comprising means for expanding the dynamic range
Assignee: Olympus Corp
•
Filing: 1998-10-22
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Granted: 2004-04-07
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Expires: 2018-10-22
Abstract
No abstract record available.
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 23:13
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/45; H04N23/70; H04N23/74; H04N25/00; H04N25/40; H04N25/42; H04N25/50; H04N25/57; H04N25/58; H04N25/587; H04N25/589; H04N25/70; H04N25/71; H04N23/50; H04N23/555
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
278 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 which
saturates at a light level which is higher than that at which the first image signal
saturates; an image signal producing means (15R, 15G, 15B) composed of first and second
weighting circuits (25, 27; 26, 28) for applying a first weight function (f), which
decreases with an increase in light level up to a light level causing the first and second
image signals to saturate respectively, and a second weight function (g), which increases
therewith, to the first and second image signals under the condition that the sum of the
first and second weight functions (f, g) is about 1; an adding circuit (29) for adding up first and second picture signals produced by
applying the first and second weight functions to the first and second image signals by
means of the first and second weighting circuits (25, 27; 26, 28) respectively; and a signal processing means (16-18) for processing a picture signal output from the
adding circuit (29) and producing a video signal according to which an image can be
displayed on a display means (19), characterized in that the first weight function (f) decreases monotonously along a curve with an
increase in light level, the second weight function (g) increases monotonously along a curve with an
increase in light level, and the second weighting circuit (26, 28) applies the second weight function to the
second image signal while keeping a sensitivity ratio of the first image signal with
respect to that of the second image signal.
Claim 2
Dependent Claim
53 words
An imaging apparatus according to claim 1, wherein the imaging means (1)
images an object during a second exposure time that is shorter than the first exposure
time, and thus outputs the second image signal which saturates at a light level which is
higher than that at which the first image signal saturates.
Claim 3
Dependent Claim
27 words
An imaging apparatus according to claim 2, further comprising an exposure time
setting means (4) for varying at least one of the first and second exposure times.
Claim 4
Dependent Claim
30 words
An imaging apparatus according to claim 3, wherein the exposure time setting
means (4) uses a waveform-detected signal produced by detecting the waveform of the
first or second image signal.
Claim 5
Dependent Claim
77 words
An imaging apparatus according to claim 1, wherein during a second exposure
time during which the second image signal is produced, an amount of light coming from
the object and falling on the imaging means (1) through an imaging window is restricted
by an amount-of-light restricting means (205, 231, 234b), and the imaging means
outputs the second image signal which saturates at a light level which is higher than that
at which the first image signal saturates.
Claim 6
Dependent Claim
80 words
An imaging apparatus according to claim 1, wherein the weight functions (f, g)
applied by the image signal producing means (15R, 15G, 15B) are such that: when a
light level is much lower than the light level causing the first image signal to saturate,
the first weight is larger than the second weight; and when the light level is higher than
the light level causing the first image signal to saturate, the second weight is larger than
the first weight.
Claim 7
Dependent Claim
38 words
An imaging apparatus according to claim 1, wherein the first weight function (f)
is cos 2 (px) where x is the image signal level and p is a coefficient, the second weight
function (g) is sin 2 (px).
Claim 8
Dependent Claim
34 words
An imaging apparatus according to claim 7, wherein the coefficient p satisfies p
≈ π/(2s) where s is a light level of light incident on the imaging window when the
second image signal saturates.
Claim 9
Dependent Claim
25 words
An imaging apparatus according to claim 1, wherein the imaging means (1)
includes a progressive imaging device having two systems of horizontal transfer output
circuits.
Claim 10
Dependent Claim
21 words
An imaging apparatus according to claim 9, wherein the signal processing means
(16-18) produces a video signal conformable to the interlacing.
Claim 11
Dependent Claim
57 words
An imaging apparatus according to claim 1, wherein the image signal producing
means (15R, 15G, 15B) includes a weight data storage means (25, 26) which stores data
of the first weight function (f) to be applied to the first image signal and data of the
second weight function (g) to be applied to the second image signal.
Claim 12
Dependent Claim
50 words
An imaging apparatus according to claim 11, wherein the weight data storage
means (25, 26) stores data of a weight function to be applied to the first image signal
and data of a weight function to be applied to the second image signal, and the weight
functions exhibits different characteristics.
Claim 13
Dependent Claim
73 words
An imaging apparatus according to claim 12, further comprising a brightness
detecting means for detecting brightness information of an object in an output signal of
the imaging means (1), wherein a weight function to be applied to the first image signal
and a weight function to be applied to the second image signal are selected based on the
brightness information of an object, and thus read from the weight data storage means
(25,26).
Claim 14
Dependent Claim
31 words
An imaging apparatus according to claim 2, wherein the imaging means (1)
images the object during the first exposure time, and produces the first image signal and
the second image signal.
Claim 15
Dependent Claim
54 words
An imaging apparatus according to claim 1, wherein the image signal producing
means (15R, 15G, 15B) produces a synthetic image 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 the second image
to saturate.
Claim 16
Dependent Claim
19 words
An imaging apparatus according to claim 15, wherein the differential coefficient
decreases monotonously with an increase in light level.
Claim 17
Dependent Claim
51 words
An endoscopic imaging apparatus, comprising: an endoscope (215) having an elongated insertion unit (217), irradiating
illumination light to an object through an illumination window located at the distal end
of the insertion unit, and including all the means (1) of the imaging apparatus
according to either one of the preceding claims.
Claim 18
Dependent Claim
46 words
An endoscopic imaging apparatus according to claim 17, further comprising a
light source unit (220') for supplying illumination light to a light guide that runs through
the insertion unit (217) of the endoscope (215), propagates illumination light, and emits
the illumination light through the illumination window.
Claim 19
Dependent Claim
77 words
An endoscopic imaging apparatus according to claim 18, wherein during a
second exposure time during which the imaging means (1) produces the second image
signal, the light source unit (220') allows an amount-of-light restricting means (205,
231, 234b) to restrict illumination light to be supplied to the light guide, and thus, the
imaging means outputs the second image signal which saturates at a light level which is
higher than that at which the first image signal saturates.
Claim 20
Dependent Claim
35 words
An endoscopic imaging apparatus according to claim 19, wherein the amount-of-light
restricting means is a light restricting filter (234b) for restricting illumination light
generated by a lamp and supplying resultant light to the light guide.
Claim 21
Dependent Claim
23 words
An endoscopic imaging apparatus according to claim 19, wherein the amount-of-light
restricting means restricts an amount of illumination light generated by a lamp.
Claim 22
Dependent Claim
58 words
An endoscopic imaging apparatus according to claim 17, wherein the endoscope
(215) is an electronic endoscope having an imaging device, which is included in the
imaging means (1) and provided with the ability to photoelectrically convert a signal,
placed on the image plane of an objecting optical system located at the distal end of the
elongated insertion unit.
Claim 23
Dependent Claim
92 words
An endoscopic imaging apparatus according to claim 17, wherein the endoscope
(215) 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 the elongated insertion unit to an eyepiece
optical system, and a TV camera that is mounted on an eyepiece portion of the optical
endoscope and has an imaging device, which is included in the imaging means and
provided with the ability to photoelectrically convert a signal, incorporated therein.
Claim 24
Dependent Claim
53 words
An endoscopic imaging apparatus according to claim 17, the endoscope (215)
includes a common image formation optical system, and the 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 the image formation
optical system.
Claim 25
Dependent Claim
31 words
An endoscopic imaging apparatus according to claim 17, wherein the imaging
device included in the imaging means has a color separation filter used to achieve color
imaging under white illumination light.
Claim 26
Dependent Claim
45 words
An endoscopic imaging apparatus according to claim 17, wherein the 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 27
Dependent Claim
52 words
An imaging apparatus according to claim 1, wherein the first weighting circuit
(25, 27) and the second weighting circuit (26, 28) apply a first weight function which
decreases monotonously and a second weight function which increases monotonously
respectively at least up to a light level causing the first image signal to saturate.
Claim 28
Dependent Claim
35 words
An imaging apparatus according to claim 27, wherein when a light level is
higher than the light level causing the first image signal to saturate, the first weighting
circuit outputs a weight coefficient of 0.
Claim 29
Dependent Claim
48 words
An imaging apparatus according to claim 27, wherein when a light level is
higher than the light level causing the first image signal to saturate, the picture signal is
determined substantially with a weight coefficient that is applied to the second image
signal by the second weighting circuit.
References Cited (Backward Citations)
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