EP1289315A2
Expired / Lapsed
EP
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Video display device and color temperature correction method for the same
Assignee: Hitachi Ltd
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Filing: 2002-03-08
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Granted: —
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Expires: 2022-03-08
Abstract
Abstract A video display device that allows the color temperature of the signals in white color attributes having high luminance and low chroma saturation to be corrected with high precision is provided together with the color temperature correction method for the same so as to visually obtain a desirable white color on display. The signal processing circuit for the color temperature correction according to this invention comprises an A/D converter to convert the video signals as input into digitalized signals, a matrix circuit to convert the digitalized signals as output from said A/D converter into luminance signals and at least two color difference signals, a hue conversion circuit to obtain hue signals from the color difference signals as output from said matrix circuit, a hue correction circuit to correct said hue signals, a chroma saturation conversion circuit to obtain chroma saturation signals from said color difference signals, a chroma saturation correction circuit to correct said chroma saturation signals and a color temperature correction circuit to perform the color temperature correction on the respective hue and chroma saturation signals as corrected.
Inventors
- 👤 Katsunobu c/o Hitachi Ltd. Int. Prop. Gr Kimura
- 👤 Takaaki c/o Hitachi Ltd. Int. Prop. Gr. Matono
- 👤 Haruki c/o Hitachi Ltd. Int. Prop. Group Takata
- 👤 Takeshi c/o Hitachi Ltd. Int. Prop. Group Sakai
- 👤 Wataru c/o Hitachi Ltd. Int. Prop. Group Kato
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 12:46
CPC Classifications
G; G09; G09G; G09G5/00; G09G5/02; H; H04; H04N; H04N9/00; H04N9/64; H04N9/73; G09G2320/00; G09G2320/06; G09G2320/0666
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
43 words
A video display device wherein said device is provided
with a means to correct a color temperature of video signals
in white color attributes having a given luminance or more and
a given chroma saturation or less among said video signals as
input.
Claim 2
Dependent Claim
97 words
A video display device comprising a signal processing
circuit provided with a color temperature correction circuit
to perform a color temperature correction on video signals as
input and a display device, to which device the video signals
as subjected to the color temperature correction by said color
temperature correction circuit are supplied for display, wherein
said color temperature correction circuit is provided with a
means to correct the color temperature of the video signals in
white color attributes having a given luminance or more and a
given chroma saturation or less among said video signals as input.
Claim 3
Dependent Claim
162 words
A video display device according to claim 2, wherein
said signal processing circuit comprises an A/D converter to
convert said video signals as input into digitalized signals,
a matrix circuit to convert the digitalized signals as output
from said A/D converter into luminance signals as well as at
least two color difference signals, a hue processing circuit
to obtain hue signals from the color difference signals as output
from said matrix circuit, a chroma saturation processing circuit
to obtain chroma saturation signals from said color difference
signals and a control circuit, wherein based on set values of
a given luminance level and a given chroma saturation level as
supplied from said control circuit said color temperature
correction circuit performs an operation to correct the color
temperature of the signals in said white attributes into a higher
level thereof among the hue signals as output from said hue
processing circuit and the chroma saturation signals as output
from said chroma saturation processing circuit.
Claim 4
Dependent Claim
144 words
A video display device according to claim 3, wherein
said color temperature correction circuit comprises a first color
temperature correction section to perform the color temperature
correction on the signals in said white color attributes among
the hue signals as output from said hue processing circuit, a
second color temperature correction section to perform the color
temperature correction on the signals in said white color
attributes among the chroma saturation signals as output from
said chroma saturation processing circuit, a first selection
circuit to select and output either the signals as output from
said first color temperature correction section or the hue signals
as output from said hue processing circuit and a second selection
circuit to select and output either the signals as output from
said second color temperature correction section or the chroma
saturation signals as output from said chroma saturation
processing circuit.
Claim 5
Dependent Claim
86 words
A video display device according to claim 4, wherein
said signal processing circuit further comprises a detection
circuit to detect an area of the signals in said white color
attributes having a given luminance or more and a given chroma
saturation or less among said video signals as input, wherein
said detection circuit upon the detection of said area outputs
a control signal to said first and second selection circuits
for selecting the signals to be output from said first and second
color temperature correction sections.
Claim 6
Dependent Claim
38 words
A video display device according to claim 5, wherein
said control circuit supplies said set values of a given luminance
level and a given chroma saturation level to said detection circuit
as a basis for detecting said area.
Claim 7
Dependent Claim
38 words
A video display device according to claim 6, wherein
said detection circuit comprises a means to further detect the
signals having a hue of a given range within the area of the
signals in said white color attributes.
Claim 8
Dependent Claim
84 words
A video display device according to claim 4, wherein
said signal processing circuit further comprises a color
difference signal conversion circuit to convert the signals as
output from the first and second selection circuits into the
color difference signals and an inverse matrix conversion circuit
to convert the color difference signals as output from said color
difference signal conversion circuit and the luminance signals
as output from said matrix circuit into R, G and B signals, which
signals are supplied to said display device.
Claim 9
Dependent Claim
184 words
A video display device according to claim 3, wherein
said hue processing circuit comprises a hue conversion circuit
to convert the color difference signals as output from said matrix
circuit into the hue signals and a hue correction circuit to
correct the signals having a given range of hue among the hue
signals as output from said hue conversion circuit so as to output
the signals as corrected to said color temperature correction
circuit, wherein said chroma saturation processing circuit
comprises a chroma saturation conversion circuit to convert the
color difference signals as output from said matrix circuit into
the chroma saturation signals and a chroma saturation correction
circuit to correct the signals having a given range of chroma
saturation among the chroma saturation signals as output from
said chroma saturation conversion circuit so as to output the
signals as corrected to said color temperature correction circuit,
wherein said control circuit sets the range and a degree of hue
to be corrected by said hue correction circuit and the range
and a degree of chroma saturation to be corrected by said chroma
saturation circuit.
Claim 10
Dependent Claim
30 words
A video display device according to claim 4, wherein
said signal processing circuit further comprises a luminance
correction circuit to correct the luminance signals as output
from said matrix circuit.
Claim 11
Dependent Claim
95 words
A video display device according to claim 10, wherein
said luminance correction circuit comprises a black expanding
circuit to control an amplitude of the signals in black color
having a given black luminance or less, a white expanding circuit
to control the amplitude of the signals in white color having
a given white luminance or more, a contrast control circuit to
control the amplitude of the signals as output from said white
expanding circuit and a brightness control circuit to control
a direct current level of the signals as output from said contrast
control circuit.
Claim 12
Dependent Claim
105 words
A video display device according to claim 11, wherein
said control circuit, based on maximum and minimum levels of
the luminance signals as output from said matrix circuit,
determines respective set values of a given black luminance and
a given white luminance so as to supply said set values to said
black and white expanding circuits while supplying the respective
set values of a degree of amplitude control of the signals to
said black expanding circuit, said white expanding circuit and
said contrast control circuit as well as the set value of the
direct current control level of the signals to said brightness
control circuit.
Claim 13
Dependent Claim
21 words
A video display device in any one of claims 3, 6,
9 or 12, wherein said control circuit is a microcomputer.
Claim 14
Dependent Claim
138 words
A video display device comprising a signal processing
circuit provided with a color temperature correction circuit
to perform a color temperature correction on video signals as
input and a display device, to which device the video signals
as subjected to the color temperature correction by said color
temperature correction circuit are supplied for display, wherein
said signal processing circuit is provided with a conversion
means to convert said video signals into digitalized hue and
chroma saturation signals, wherein said color temperature
correction circuit, which circuit performs the color temperature
correction on the respective hue and chroma saturation signals
as converted, is provided with a correction means to increase
the color temperature of the signals in white color attributes
having a given luminance or more and a given chroma saturation
or less among said hue and chroma saturation signals.
Claim 15
Dependent Claim
52 words
A video display device according to claim 14, wherein
said correction means is provided with a means to make a hue
of the signals in said white color attributes closer to the hue
of blue color and a means to enhance the chroma saturation of
the signals in said white color attributes.
Claim 16
Dependent Claim
38 words
Color temperature correction method to perform the
color temperature correction on video signals as input, wherein
the color temperature correction is performed on the signals
in white color attributes having a given range of luminance and
chroma saturation.
Claim 17
Dependent Claim
57 words
Color temperature correction method to perform the
color temperature correction on video signals as input, wherein
an operation is performed to correct the color temperature of
respective hue and chroma saturation components of the signals
in white color attributes having a given luminance or more and
a given chroma saturation or less among said signals as input.
Claim 18
Dependent Claim
38 words
Color temperature correction method according to
claim 17, wherein the color temperature correction for the signals
in said white color attributes is independently performed from
that for the video signals other than those in said white color
attributes.
Claim 19
Dependent Claim
83 words
Color temperature correction method to perform the
color temperature correction on video signals as input comprising
the steps of converting said video signals into digitalized
signals, separating said digitalized signals into luminance
signals and color difference signals, separating said color
difference signals into hue signals and chroma saturation signals
and performing the color temperature correction to increase the
color temperature of the signals in white color attributes having
a given luminance and a given chroma saturation among said hue
and chroma saturation signals.
Claim 20
Dependent Claim
48 words
Color temperature correction method according to
claim 19, wherein said color temperature correction comprises
the steps of making a hue of the signals in said white color
attributes closer to the hue of blue color and enhancing the
chroma saturation of the signals in said white color attributes.
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