U.S. patent application number 14/284073 was filed with the patent office on 2014-09-11 for method of driving display apparatus and driving circuit for display apparatus using the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to KYUNG-WOO KIM, SEON-KI KIM, JAE-HO OH, MIN-KYU PARK, BYUNG-HYUK SHIN.
Application Number | 20140253528 14/284073 |
Document ID | / |
Family ID | 41673899 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140253528 |
Kind Code |
A1 |
SHIN; BYUNG-HYUK ; et
al. |
September 11, 2014 |
METHOD OF DRIVING DISPLAY APPARATUS AND DRIVING CIRCUIT FOR DISPLAY
APPARATUS USING THE SAME
Abstract
In a driving method of a display apparatus using a driving
circuit, when an image signal is a film image signal, first,
second, and third original image signals are extracted based on the
film image signal. Then, a first compensation image signal is
generated based on first and second original image signals, and a
second compensation image signal is generated based on second and
third original image signals. The first original image signal, the
first compensation image signal, the second original image signal,
and the second compensation image signal are sequentially output to
have a driving frequency higher than an input frequency. In
addition, the first original image signal, the first compensation
image signal, the second original image signal, and the second
compensation image signal are output i, k, j, and k times,
respectively. Thus, a trembling phenomenon perceived by a viewer of
a film image may be prevented.
Inventors: |
SHIN; BYUNG-HYUK; (SEOUL,
KR) ; PARK; MIN-KYU; (ASAN-SI, KR) ; KIM;
SEON-KI; (ANYANG-SI, KR) ; OH; JAE-HO; (SEOUL,
KR) ; KIM; KYUNG-WOO; (CHEONAN-SI, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
SUWON-SI |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
SUWON-SI.
KR
|
Family ID: |
41673899 |
Appl. No.: |
14/284073 |
Filed: |
May 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12356584 |
Jan 21, 2009 |
|
|
|
14284073 |
|
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|
|
Current U.S.
Class: |
345/208 |
Current CPC
Class: |
G09G 2310/0243 20130101;
G09G 2340/14 20130101; G09G 2320/02 20130101; H04N 7/0115 20130101;
G09G 2310/06 20130101; G09G 2340/0435 20130101; H04N 7/0132
20130101; G09G 3/20 20130101 |
Class at
Publication: |
345/208 |
International
Class: |
G09G 3/20 20060101
G09G003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 14, 2008 |
KR |
10-2008-0080064 |
Claims
1. A method of driving a display apparatus, comprising: receiving
an image signal in response to a synchronizing signal having a
first frequency; discriminating whether the received image signal
is a signal corresponding to a film image or a signal corresponding
to a video image; converting the synchronizing signal into a
driving signal having a second frequency higher than the first
frequency; extracting, if the image signal is discriminated to be a
film image signal corresponding to the film image, successive first
and second original image signals based on the film image signal;
and sequentially outputting the first and second original image
signals i times in response to the driving signal.
2. The method of claim 1, wherein the discriminating of the
received image signal comprises: receiving the image signal as an
n-th image signal, a previously-stored (n-1)-th image signal, and a
previously-stored (n-2)-th image signal and calculating first,
second, and third brightness values corresponding to the n-th image
signal, the (n-1)-th image signal, and the (n-2)-th image signal,
respectively; calculating a first difference value corresponding to
a difference between the first and second brightness values and a
second difference value corresponding to a difference between the
second and third brightness values; and comparing the first and
second difference values with a predetermined reference value to
discriminate whether the image signal is the signal corresponding
to the film image or the signal corresponding to the video
image.
3. The method of claim 2, wherein the comparing of the first and
second difference values with the reference value comprises:
comparing the second difference value with the reference value if
the first difference value is smaller than the reference value and
discriminating that the n-th image signal is the signal
corresponding to the video image if the first difference value is
greater than the reference value; calculating a third difference
value corresponding to a difference between the third brightness
value and a fourth brightness value corresponding to an (n+1)-th
image signal and calculating a fourth difference value
corresponding to a difference between the fourth brightness value
and a fifth brightness value corresponding to an (n+2)-th image
signal; and comparing the third difference value with the reference
value if the second difference value is smaller than the reference
value and comparing the fourth difference value with the reference
value if the second difference value is greater than the reference
value to discriminate whether the n-th image signal is the signal
corresponding to a still image or the signal corresponding to the
film image.
4. The method of claim 3, wherein the comparing of the third and
fourth difference value with the reference value comprises:
discriminating that the n-th image signal is the signal
corresponding to the still image if the third difference value is
smaller than the reference value and comparing the fourth
difference value with the reference value if the third difference
value is greater than the reference value; and discriminating that
the n-th image signal is the signal corresponding to the film image
if the fourth difference value is smaller than the reference value
and that the n-th image signal is the signal corresponding to the
video image if the fourth difference value is greater than the
reference value.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Divisional Application of U.S. patent
application Ser. No. 12/356,584, filed on Jan. 21, 2009, and claims
priority to and the benefit of Korean Patent Application No.
2008-80064 filed on Aug. 14, 2008, the entire contents of both of
which are incorporated by reference herein.
BACKGROUND
[0002] 1. Technical Field The present disclosure relates to a
method of driving a display apparatus and a driving circuit for a
display apparatus using the driving method, which are capable of
preventing a trembling phenomenon of a film image.
[0003] 2. Discussion of Related Art
[0004] In general, a display apparatus receives image signals from
an external system and displays images corresponding to the image
signals on a screen.
[0005] The display apparatus, recently, has been applied to various
fields, and thus the display apparatus displays not only a normal
video image but also a film image that was recorded in photographic
film.
[0006] Because the film image is recorded in the photographic film
at 24 frames per second and the display apparatus is operated at 60
Hz, however, the external system applies the film image signal to
the display apparatus after converting the film image signal
recorded at 24 frames per second into an image signal at 60 frames
per second.
[0007] In order to convert the film image recorded at 24 frames per
second into an image at 60 frames per second for display,
odd-numbered frames among the 24 frames are repeated three times
and even-numbered frames among the 24 frames are repeated two
times, thereby expanding the film image recorded at 24 frames per
second into film image at 60 frames per second.
[0008] When applying the above-described method, however, the human
eye recognizes a trembling phenomena of the images displayed on the
display apparatus because the odd-numbered frames have different
display intervals from the display intervals of the even-numbered
frames. As a result, when displaying the expanded film image on the
display apparatus, display characteristics of the display apparatus
are degraded.
SUMMARY
[0009] An exemplary embodiment of the present invention provides a
method of driving a display apparatus capable of preventing a
trembling phenomenon of a converted film image.
[0010] An exemplary embodiment of the present invention also
provides a driving circuit for a display apparatus using the
driving method.
[0011] In an exemplary embodiment of the present invention, a
method of driving a liquid crystal display apparatus includes
receiving an image signal in response to a synchronizing signal
having a first frequency; discriminating whether the image signal
is a signal corresponding to a film image or a signal corresponding
to a video image; converting the synchronizing signal into a
driving signal having a second frequency higher than the first
frequency; extracting, when the image signal is the film image
signal corresponding to the film image, first, second and third
original image signals based on the film image signal, which are
successive; generating a first compensation image signal based on
the first original image signal and the second original image
signal and generating a second compensation image signal based on
the second original image signal and the third original image
signal; and sequentially outputting the first original image
signal, the first compensation image signal, the second original
image signal, and the second compensation image signal in response
to the driving signal. The first original image signal, the first
compensation image signal, the second original image signal, and
the second compensation image signal are output i times, k times, j
times, and k times, respectively.
[0012] In an exemplary embodiment of the present invention, a
method of driving a display apparatus includes receiving an image
signal in response to a synchronizing signal having a first
frequency; discriminating whether the received image signal is a
signal corresponding to a film image or a signal corresponding to a
video image; converting the synchronizing signal into a driving
signal having a second frequency higher than the first frequency;
extracting, if the image signal is a film image signal
corresponding to the film image, first and second original image
signals based on the film image signal, which are successive; and
sequentially outputting the first and second original image signals
i times in response to the driving signal.
[0013] In an exemplary embodiment of the present invention, a
driving circuit for a display apparatus receives an image signal
based on a synchronizing signal having a first frequency. The
driving circuit includes an image signal discriminator, an original
image signal extractor, an image signal converter, a frequency
modulator, and a data outputter.
[0014] The image signal discriminator discriminates whether the
image signal is a signal corresponding to a film image or a signal
corresponding to a video image, and the original image signal
extractor extracts first, second and third original image signals,
which are successive, based on a film image signal if the image
signal is the film image signal corresponding to the film
image.
[0015] The image signal converter generates first and second
compensation image signals based on the first, second and third
original image signals, and the frequency modulator converts the
synchronizing signal into a driving signal having a second
frequency higher than the first frequency.
[0016] The data outputter outputs the first original image signal i
times, the second original image signal j times, the first
compensation image signal k times, and the second compensation
image signal k times.
[0017] According to the above-described exemplary embodiment, the
original image signal is extracted from the film image signal, the
compensation image signal is generated based on the extracted
original image signal, and the original image signal and the
compensation image signal have a frequency higher than a frequency
of the film image signal. Thus, a trembling phenomenon of the film
image may be prevented, and interruption of the displayed image,
which is caused by an abrupt motion variation, may be
prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Exemplary embodiments of the present invention will be
understood in more detail from the following descriptions taken in
conjunction with the accompanying drawings, wherein:
[0019] FIG. 1 is a block diagram showing an exemplary embodiment of
a driving circuit for a display apparatus according to the present
invention;
[0020] FIG. 2 is a representation useful in explaining a driving
method of the driving circuit shown in FIG. 1;
[0021] FIG. 3 is a representation showing a state in which a film
image signal of 60 Hz is converted into a film image signal of 96
Hz;
[0022] FIGS. 4 to 6 are representations showing states in which a
film image signal of 60 Hz is converted into a film image signal of
120 Hz;
[0023] FIG. 7A is a view showing an image of an n-th frame;
[0024] FIG. 7B is a histogram showing the brightness distribution
of the image shown in FIG. 7A;
[0025] FIG. 8A is a view showing an image of an (n+1)-th frame;
[0026] FIG. 8B is a histogram showing the brightness distribution
of the image shown in FIG. 8A;
[0027] FIG. 9 is a histogram showing a brightness difference
between the n-th frame and the (n+1)-th frame;
[0028] FIG. 10A is a view showing an image of an n-th frame;
[0029] FIG. 10B is a histogram showing the brightness distribution
of the image shown in FIG. 10A;
[0030] FIG. 11A is a view showing an image of an (n+1)-th
frame;
[0031] FIG. 11B is a histogram showing the brightness distribution
of the image shown in FIG. 11A;
[0032] FIG. 12 is a histogram showing a brightness difference
between the n-th frame and the (n+1)-th frame; and
[0033] FIG. 13 is a flow chart illustrating an operation process of
an image signal discriminator shown in FIG. 1.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0034] Hereinafter, exemplary embodiments of the present invention
will be explained in detail with reference to the accompanying
drawings.
[0035] FIG. 1 is a block diagram showing an exemplary embodiment of
a driving circuit for a display apparatus according to the present
invention, and FIG. 2 is a representation useful in explaining a
driving method of the driving circuit shown in FIG. 1.
[0036] Referring to FIG. 1, a driving circuit 100 for a display
apparatus includes an image signal discriminator 110, an original
image signal extractor 120, a memory 130, an image signal converter
140, a data outputter 150, and a frequency modulator 160.
[0037] The image signal discriminator 110 receives an image signal
from an external system (not shown) and discriminates whether the
image signal is a normal image signal used to display a normal
video image or a film image signal used to display a film image. On
the assumption that the display apparatus is applied to a
television set, the normal image is defined as an image presented
through a normal broadcasting service and the film image is defined
as an image of a moving picture reproduced by using a film.
[0038] The normal image signal may be provided to the driving
circuit 100 at a frequency of 60 Hz, however, because the film
image signal is recorded onto a film at a frequency of 24 Hz, the
film image signal of 24 Hz may be provided to the driving circuit
100 after being converted to an image signal of 60 Hz by the
external system (not shown).
[0039] As shown in FIG. 2, the external system receives 24 frame
data per second (24 Hz) and outputs 60 frame data per second (60
Hz). To this end, the external system repeatedly outputs
odd-numbered frame data of the 24 frame data three times and
repeatedly outputs even-numbered frame data of the 24 frame data
two times, so that the external system may output the 60 frame data
using the 24 frame data. Accordingly, the film image signal F2-data
converted to have the frequency of 60 Hz by the external system is
sequentially applied to the image signal discriminator 110.
[0040] The image signal discriminator 110 receives the image signal
F2-data from the external system (not shown) and discriminates
whether the image signal is the normal image signal or the film
image signal. If the image signal is the film image signal, the
image signal discriminator 110 provides the film image signal
F2-data and a discrimination signal S1 indicating that the image
signal is the film image signal F2-data to the original image
signal extractor 120.
[0041] The original image signal extractor 120 is operated in
response to the discrimination signal S1. The original image signal
extractor 120 converts the film image signal F2-data of 60 Hz into
the film image signal F1-data of 24 Hz, and extracts original image
signal from the converted film image signal of 24 Hz. That is, the
original image signal extractor 120 extracts 24 original image
signals (24 Hz) from 60 film image signals (60 Hz) sequentially
applied from the image signal discriminator 110. Then, the 24
original image signals extracted by the original image signal
extractor 120 are sequentially stored into the memory 130.
[0042] In addition, the original image signal extractor 120 reads
out from the memory 130 first and second original image signals A1
and A2 corresponding to two successive frames of the 24 original
image signals, and provides the first and second original image
signals A1 and A2 to the image signal converter 140.
[0043] The image signal converter 140 generates first and second
compensation image signals A11 and A12 using motion vectors
generated based on the first and second original image signal A1
and A2. More specifically, each of the first and second
compensation image signals A11 and A12 serves as a signal that
displays a respective one of several intermediate images existing
between a first original image corresponding to the first original
image signal A1 and a second original image corresponding to the
second original image signal A2.
[0044] As shown in FIG. 2, in the present exemplary embodiment, the
first original image signal A1 is used to display a star located at
a first position, and the second original image signal A2 is used
to display the star located at a second position. A motion vector
of the star is calculated using the first and second original image
signals A1 and A2. Then, based on the motion vector, the image
signal converter 140 generates the first and second compensation
image signals A11 and A12 to display stars located on a moving path
of the star between the first original image signal A1 and the
second original image signal A2.
[0045] The first original image signal A1, the first compensation
image signal A11, and the second compensation image signal A12 are
provided to the data outputter 150 from the image signal converter
140. In addition, the data outputter 150 receives a driving signal
DRS having a frequency of 72 Hz from the frequency modulator 160.
The frequency modulator 160 receives a synchronizing signal of 60
Hz from the external system (not shown), modulates the frequency of
the synchronizing signal, and outputs the driving signal DRS of 72
Hz to the data outputter 150. Thus, the data outputter 150
sequentially outputs the first original image signal A1, the first
compensation image signal A11, and the second compensation image
signal A12 as F3-data in response to the driving signal DRS having
the frequency of 72 Hz.
[0046] Then, the original image signal extractor 120 reads out the
second original image signal A2 and a third original image signal
A3 shown in FIG. 2 from the memory 130 and provides the second and
third original image signals A2 and A3 to the image signal
converter 140. The image signal converter 140 generates third and
fourth compensation image signals A21 and A22 shown in FIG. 2 using
a motion vector calculated based on the second and third original
image signals A2 and A3. Each of the third and fourth compensation
image signals A21 and A22 serves as a signal that displays one of
the intermediate images existing between the second original image
corresponding to the second original image signal A2 and a third
original image corresponding to the third original image signal
A3.
[0047] The second original image signal A2, the third compensation
image signal A21, and the fourth compensation image signal A22 are
provided to the data outputter 150. The data outputter 150
sequentially outputs the second original image signal A2, the third
compensation image signal A21, and the fourth compensation image
signal A22 in response to the driving signal DRS of 72 Hz.
[0048] As shown in FIG. 2, the data outputter 150 sequentially
outputs the first original image signal A1, the first compensation
image signal A11 and the second compensation image signal A12
during 3/72 seconds, which corresponds to a 1/24 of a second, and
sequentially outputs the second original image signal A2, the third
compensation image signal A21 and the fourth compensation image
signal A22 during a next 3/72 seconds, which corresponds to a 1/24
of a second.
[0049] When repeatedly performing the above-described processes,
the driving circuit 100 for the display apparatus may convert the
film image signal F2-data of 60 Hz into the film image signal
F3-data of 72 Hz, thereby applying the film image signal F3-data to
a display panel (not shown).
[0050] In other words, in the previously known system when
odd-numbered original image signals A1 and A3 among 24 original
image signals are repeated three times and even-numbered original
image signals A2 and A4 among the 24 original image signals are
repeated three times in order to display 24 original image signals
at 60 Hz, the star is displayed at different times in each frame.
As a result, it appears to the human eye that the image is
trembling.
[0051] On the other hand, according to an exemplary embodiment of
the present invention, when the 24 original image signals are
converted into 72 Hz, each original image signal is repeatedly
displayed, thereby preventing the trembling phenomena of the
displayed image. In addition, because the compensation image signal
is inserted between the original image signals at least one time,
interruption of the displayed image, which is caused by an abrupt
motion variation, may be prevented.
[0052] In FIGS. 1 and 2, a process that the film image signal
F2-data of 60 Hz is converted into the film image signal F3-data of
72 Hz has been described, but the film image signal F2-data of 60
Hz may also be converted into a film image signal F4-data of 96 Hz
or a film image signal F5-data of 120 Hz according to other
exemplary embodiments of the present invention. Hereinafter, a
process that converts the film image signal F2-data into the film
image signal F4-data of 96 Hz will be described with reference to
FIG. 3, and a process that converts the film image signal F2-data
into the film image signal F5-data of 120 Hz will be described with
reference to FIG. 4.
[0053] FIG. 3 is a representation showing a state in which a film
image signal of 60 Hz is converted into a film image signal of 96
Hz. In the present exemplary embodiment, a driving circuit used to
convert the film image signal F2-data of 60 Hz into the film image
signal F4-data of 96 Hz has the same circuit configuration as that
of the driving circuit 100 of FIG. 1, however, the frequency
modulator 160 modulates the synchronizing signal Sync into a
driving signal DRS having a frequency of 96 Hz and the driving
signal DRS of 96 Hz is applied to the data outputter 150.
Accordingly, the process that converts the film image signal
F2-data of 60 Hz into the film image signal F4-data of 96 Hz will
be described with reference to FIGS. 1 and 3.
[0054] Referring to FIGS. 1 and 3, the image signal discriminator
110 receives the image signal F2-data from the external system (not
shown) and discriminates whether the image signal F2-data is the
normal video image signal or the film image signal. If the image
signal is the film image signal, the original image signal
extractor 120 extracts the original image signal from the film
image signal of 60 Hz. Then, the original image signal extractor
120 reads out first and second original image signals A1 and A2
adjacent each other among the extracted 24 original image signals,
and provides the first and second original image signals A1 and A2
to the image signal converter 140.
[0055] The image signal converter 140 generates a first
compensation image signal A12 based on the first and second
original image signals A1 and A2. The first original image signal
A1 and the second compensation image signal A12 shown in FIG. 3 are
provided to the data outputter 150.
[0056] The frequency modulator 160 receives the synchronizing
signal Sync of 60 Hz from the external system and modulates the
frequency of the synchronizing signal Sync to output the driving
signal DRS having the frequency of 96 Hz to the data outputter 150.
Thus, the data outputter 150 outputs the first original image
signal A1 and the second compensation image signal A12 in response
to the driving signal DRS having the frequency of 96 Hz.
[0057] As shown in FIG. 3, the data outputter 150 outputs the first
original image signal A1 two times, and then outputs the second
compensation image signal A12 two times during the 4/96 seconds,
which again is a 1/24 of a second.
[0058] Then, the second original image signal A2 and a fifth
compensation image signal A23 are provided to the data outputter
150. Accordingly, the data outputter 150 outputs the second
original image signal A2 and the fifth compensation image signal
A23 two times during next 4/96 seconds.
[0059] When repeatedly performing the above-described processes,
the driving circuit 100 for the display apparatus may convert the
film image signal F2-data of 60 Hz into the film image signal
F4-data of 96 Hz, thereby applying the film image signal F4-data to
a display panel (not shown).
[0060] As described above, when the film image signal F2-data of 60
Hz is converted into the film image signal F4-data of 96 Hz, each
original image signal is repeatedly displayed two times, thereby
preventing the trembling phenomena of the displayed image. In
addition, since the compensation image signal is inserted between
the original image signals, interruption of the displayed image may
be prevented.
[0061] FIG. 4 is a view showing a state in which a film image
signal of 60 Hz is converted into a film image signal of 120 Hz. In
FIG. 4, a further description of the same processes as those
described in relation to FIGS. 1 to 3 will be omitted in order to
avoid redundancy.
[0062] Referring to FIGS. 1 and 4, during a first 5/120 seconds,
the data outputter 150 outputs the first original image signal A1
three times and outputs the second compensation image signal A12
two times.
[0063] Then, during the next 5/120 seconds, the data outputter 150
outputs the second original image signal A2 three times and outputs
the fifth compensation image signal A23 two times. When repeatedly
performing the above-described processes, the driving circuit 100
for the display apparatus may convert the film image signal F2-data
of 60 Hz into the film image signal F5-data of 120 Hz, thereby
applying the film image signal F5-data to a display panel (not
shown).
[0064] As described above, when the film image signal F2-data of 60
Hz is converted into the film image signal F5-data of 120 Hz, each
original image signal is repeatedly displayed three times, thereby
preventing the trembling phenomena of the displayed image present
in previously proposed systems. In addition, because the
compensation image signal is inserted between the original image
signals, interruption of the displayed image is prevented.
[0065] FIG. 5 is a representation showing a state in which a film
image signal of 60 Hz is converted into a film image signal of 120
Hz.
[0066] Referring to FIG. 5, the data outputter 150 outputs the
first original image signal A1 five times during 5/120 seconds, and
outputs the second original image signal A2 five times during next
5/120 seconds. Thus, the driving circuit 100 for the display
apparatus may convert the film image signal F2-data of 60 Hz into
the film image signal F6-data of 120 Hz, thereby applying the film
image signal F6-data to a display panel (not shown).
[0067] As described above, when the film image signal F2-data of 60
Hz is converted into the film image signal F6-data of 120 Hz, each
original image signal is repeatedly displayed five times, thereby
preventing the trembling phenomena of the displayed image.
[0068] FIG. 6 is view showing a state in which a film image signal
of 60 Hz is converted into a film image signal of 120 Hz.
[0069] Referring to FIG. 6, during 6/120 seconds, the data
outputter 150 outputs the first original image signal A1 five times
and then outputs one second compensation image signal A12. In FIG.
6, the second compensation image signal A12 serves as a signal that
displays one of intermediate images existing between the first
original image corresponding to the first original image signal A1
and the second original image corresponding to the second original
image signal A2.
[0070] Next, during 4/120 seconds, the data outputter 150 outputs
the second original image signal A2 three times and then outputs
the fifth compensation image signal A23. The fifth compensation
image signal A23 serves as a signal that displays one of the
intermediate images existing between the second original image
corresponding to the second original image signal A2 and the third
original image corresponding to the third original image signal
A3.
[0071] When repeatedly performing the above-described processes,
the driving circuit 100 for the display apparatus may convert the
film image signal F2-data of 60 Hz into the film image signal
F7-data of 120 Hz, thereby applying the film image signal F7-data
to a display panel (not shown).
[0072] As described above, the film image signal F2-data of 60 Hz
is converted into the film image signal F6-data of 120 Hz, and the
compensation image signal is inserted between the original image
signals at least one time, so that interruption of the displayed
image, which is caused by an abrupt motion variation, may be
prevented.
[0073] FIG. 7A is a view showing an image of an n-th frame, and
FIG. 7B is a histogram showing the brightness distribution of the
image shown in FIG. 7A. FIG. 8A is a view showing an image of an
(n+1)-th frame, and FIG. 8B is a histogram showing the brightness
distribution of the image shown in FIG. 8A. In FIGS. 7B and 8B, an
x-axis represents a gray scale and a y-axis represents a number of
pixels.
[0074] Comparing FIGS. 7A and 8A, it is seen that there is no
movement between an image of the n-th frame and an image of the
(n+1)-th. In this case, as shown in FIGS. 7B and 8B, the n-th frame
and the (n+1)-th frame have the same brightness distribution.
[0075] FIG. 9 is a histogram showing a brightness difference
between an n-th frame and an (n+1)-th frame.
[0076] Referring to FIG. 9, the difference of the brightness
histograms between the n-th frame and the (n+1)-frame has been
observed as zero. That is, because the brightness difference
between the n-th frame and the (n+1)-th frame is zero, the n-th
frame and the (n+1)-th frame display the same image, which
corresponds to FIGS. 7A and 8A.
[0077] FIG. 10A is a view showing an image of an n-th frame and
FIG. 10B is a histogram showing the brightness distribution of the
image shown in FIG. 10A. FIG. 11A is a view showing an image of an
(n+1)-th frame and FIG. 11B is a histogram showing the brightness
distribution of the image shown in FIG. 11A. In FIGS. 10B and 11B,
an x-axis indicates a gray scale and a y-axis indicates a number of
pixels.
[0078] Referring to FIGS. 10A and 11A, when comparing the n-th
frame with the (n+1)-th frame, it is seen that the image of the
(n+1)-th frame has been moved toward a left side. In this case, as
shown in FIGS. 10B and 11B, the n-th frame and the (n+1)-th frame
have a respective brightness different from each other.
[0079] FIG. 12 is a histogram showing a brightness difference
between the n-th frame and the (n+1)-th frame, wherein the X-axis
represents a gray scale and the Y-axis represents the number of
pixels.
[0080] Referring to FIG. 12, the difference of brightness
histograms between the n-th frame and the (n+1)-frame has been
observed. In this manner, when comparing the brightness histogram
of the n-th frame and the brightness histogram of the (n+1)-th
frame, a state may be observed, in which the n-th frame and the
(n+1)-th frame display different images from each other or the
image of the (n+1)-th frame moves relative to the n-th frame.
[0081] According to an exemplary embodiment of the present
invention, the image signal discriminator 110 shown in FIG. 1
compares the brightness histograms with each other to discriminate
whether the image signal applied from the external system is the
normal video image signal or the film image signal. That is,
because the film image signal of 60 Hz is repeatedly applied three
times or two times from the external system, if the brightness
difference does not occur during the three times or two times, the
image signal is considered as the film image signal.
[0082] FIG. 13 is a flow chart illustrating an operation process of
the image signal discriminator 110 shown in FIG. 1.
[0083] Referring to FIG. 13, the image signal discriminator 110
receives the image signal corresponding to the n-th frame through a
low-voltage differential signaling (LVDS) (S201). The image signal
discriminator 110 calculates brightness data L(n) of the image
signal of the n-th frame based on the input image signal (S202a).
The calculated brightness L(n) is stored in first and second frame
memories (S202b and S202c). The first and second frame memories
sequentially store brightness data for every frame.
[0084] Based on the n-th brightness data L(n) of the input image
signal, the (n-1)-th brightness data L(n-1) read-out from the first
frame memory, and the (n-2)-th brightness data L(n-2) read-out from
the second frame memory, the difference of the brightness histogram
between two adjacent frames is obtained (S203). More specifically,
an absolute value obtained by subtracting the (n-1)-th brightness
histogram LH(n-1) from the n-th brightness histogram LH(n) is
defined as a first brightness difference value DIF_LH(n), and an
absolute value obtained by subtracting the (n-2)-th brightness
histogram LH(n-2) from the (n-1)-th brightness histogram LH(n-1) is
defined as a second brightness difference value DIF_LH(n-1)
(S203).
[0085] In FIG. 13, only the first and second brightness difference
values DIF_LH(n) and DIF_LH(n-1) have been described but, if
necessary, third and fourth brightness difference values
DIF_LH(n+1) and DIF_LH(n+2) may be sequentially calculated using
the (n+1)-th and the (n+2)-th brightness histograms.
[0086] The first brightness difference value DIF_LH(n) is compared
with a predetermined reference value REF to discriminate whether
the first brightness difference value DIF_LH(n) is smaller than the
predetermined reference value REF (S204). If the first brightness
difference value DIF_LH(n) is smaller than the reference value REF,
the second brightness difference value DIF_LH(n-1) is compared with
the reference value REF (S205). If the first brightness difference
value DIF_LH(n) is equal to or greater than the reference value
REF, a signal indicating that the input image signal is the normal
image signal is output (S209d).
[0087] Then, if the second brightness difference value DIF_LH(n-1)
is smaller than the reference value REF, the third brightness
difference value DIF_LH(n+1) is compared with the reference value
REF (S206). If the second brightness difference value DIF LH(n-1)
is equal to or greater than the reference value REF, the fourth
brightness difference value DIF_LH(n+2) is compared with the
reference value REF (S207).
[0088] If the third brightness difference value DIF_LH(n+1) is
smaller than the reference value REF, a signal indicating that the
normal image signal is a still image is output (S209a).
[0089] If, the third brightness difference value DIF_LH(n+1) is
equal to or greater than the reference value REF, the fourth
brightness difference value DIF_LH(n+2) is compared with the
reference value REF (S208).
[0090] In the step S208, if the fourth brightness difference value
DIF_LH(n+2) is smaller than the reference value REF, a signal is
output indicating that the input image signal is the film image
signal to which a 3:2 pull-down scheme, for example, a 60 Hz
driving scheme, is applied (S209b). If the fourth brightness
difference value DIF_LH(n+2) is equal to or greater than the
reference value REF, the signal is output indicating the input
image signal is the normal image signal (S209d).
[0091] In the step S207, if the fourth brightness difference value
DIF_LH(n+2) is smaller than the reference value REF, a signal is
output indicating that the input image signal is the film image
signal to which a 2:2 pull-down scheme, for example, a 60 Hz
driving scheme is applied (S209c). If the fourth brightness
difference value DIF_LH(n+2) is equal to or greater than the
reference value REF, the signal is output indicating the input
image signal is the normal image signal is output (S209d).
[0092] As described above, using the brightness histogram of each
frame, the input image signal may be easily discriminated as to
whether the input image signal is the film image signal or the
normal image signal.
[0093] In an exemplary embodiment, the original image signal is
extracted from the film image signal, the compensation image signal
is generated based on the extracted original image signal, and the
original image signal and the compensation image signal are set to
have a frequency higher than a frequency of the film image signal.
Thus, a trembling phenomenon perceived by the viewer of the film
image may be prevented, and an interruption of the displayed image,
which is caused by an abrupt motion variation, may be
prevented.
[0094] Although exemplary embodiments of the present invention have
been described, it is understood that the present invention should
not be limited to these exemplary embodiments and various changes
and modifications can be made by one of ordinary skill in the art
within the spirit and scope of the present invention as hereinafter
claimed.
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