Patent Publication Number: US-2007109431-A1

Title: Video processing apparatus and video processing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims priority under 35 U.S.C.§119 from Korean Patent Application No. 10-2005-0110324, filed on Nov. 17, 2005, the entire disclosure of which is hereby incorporated by reference.  
     BACKGROUND OF INVENTION  
      1. Field of Invention  
      Apparatuses and methods consistent with the present invention relate to video processing, and more particularly, to a video processing apparatus and a video processing method which are capable of compensating/correcting a video signal.  
      2. Description of the Related Art  
      A video processing apparatus, such as a television (TV), receives a video signal from a broadcasting station or an external device such as a video cassette recorder (VCR), a digital versatile disc (DVD) player, a personal computer (PC) or the like, performs video processing suitable for the received video signal, and displays a video based on the processed video signal.  
      According to a related art video processing apparatus, however, gamma correction is operated to correct an error caused by a difference between the strength and the luminance (or the brightness) of the video signal. But the gamma correction alone is insufficient to improve the quality of a video.  
     SUMMARY OF THE INVENTION  
      The present invention provides a video processing apparatus and a video processing method which are capable of improving the quality of a video.  
      According to an aspect of the present invention, there is provided a video processing apparatus comprising: a storing unit which stores first pixel data of a first frame of a video, second pixel data of a second frame of the video, a first correction factor, and a second correction factor, wherein the first frame precedes the second frame, the first correction factor corresponds to a difference between the first pixel data and the second pixel data, and the second correction factor corresponds to the first pixel data; and a correction performing unit which corrects the first pixel data by simultaneously applying the first correction factor and the second correction factor.  
      According to another aspect of the present invention, the second correction factor corresponds to a difference between the strength of a video indicated by the first pixel data and the brightness of the video indicated by the first pixel data.  
      According to still another aspect of the present invention, the video processing apparatus further comprises a liquid crystal display (LCD) which displays the video based on the first pixel data.  
      According to still another aspect of the present invention, there is provided a video processing method comprising: storing a first correction factor corresponding to a difference between first pixel data of a first frame of a video and second pixel data of a second frame of the video, wherein the first frame precedes the second frame; storing a second correction factor corresponding to the first pixel data; storing the first pixel data; storing the second pixel data; and correcting the first pixel data by simultaneously applying the first correction factor and the second correction factor.  
      According to still another aspect of the present invention, the second correction factor corresponds to a difference between the strength of a video indicated by the first pixel data and the brightness of the video indicated by the first pixel data.  
      According to still another aspect of the present invention, the video processing method further comprises displaying the video based on the corrected first pixel data on an LCD. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and/or other aspects of the prevent invention will become apparent and more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompany drawings, in which:  
       FIG. 1  is a block diagram illustrating a configuration of a video processing apparatus according to a first exemplary embodiment of the present invention;  
       FIG. 2  is a block diagram illustrating a detailed configuration of a response time compensating part and a gamma correcting part in the video processing apparatus of  FIG. 1 , according to an exemplary embodiment of the present invention;  
       FIG. 3  is a schematic block diagram illustrating a configuration of a video processing apparatus according to a second exemplary embodiment of the present invention;  
       FIG. 4  is a block diagram illustrating a detailed configuration of a correcting part in the video processing apparatus of  FIG. 3 , according to an exemplary embodiment of the present invention; and  
       FIG. 5  is a flow chart illustrating a video processing method according to an exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
      Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.  
      A configuration of a video processing apparatus  1  according to a first exemplary embodiment of the present invention is shown in  FIG. 1 . The video processing apparatus  1  may be an LCD TV or the like. The video processing apparatus  1  receives a video signal from a broadcasting station or an external device (not shown) such as a VCR, a DVD player, a PC or the like, suitably processes the received video signal, and displays a video based on the processed video signal. The video processing apparatus  1  includes a signal receiving part  11 , a decoding part  12 , a scaling part  13 , a response time compensating part  14 , a gamma correcting part  15 , and a displaying part  16 . The signal receiving part  11  receives a video signal from a broadcasting station or the like and tunes the received video signal to a frequency corresponding to a channel selected by a user. The decoding part  12  decodes the video signal tuned by the signal receiving part  11  and outputs the decoded video signal to the displaying part  16  as a video signal of a type which can be displayed on displaying part  16 . The scaling part  13  adjusts resolution of the video signal decoded by the decoding part  12  based on a user&#39;s setting and a characteristic of the displaying part  16 . The response time compensating part  14  compensates a response time delay caused by the characteristic of the displaying part  16  such as an LCD. The gamma correcting part  15  corrects an error caused by a difference between the strength and the brightness (or luminance) of the video signal. The displaying part  16  displays the video based on the corrected video signal. Herein, the response time compensating part  14  compensates a characteristic such as a gray-to-gray response time of an LCD. The gamma correcting part  15  performs the correction so as to overcome a problem that colors in regions of low brightness and/or medium brightness are distorted since a gamma characteristic (or gamma curve) does not correspond to a standard gamma characteristic.  
      More detailed structures of the response time compensating part  14  and the gamma correcting part  15  in the video processing apparatus  1  of  FIG. 1  are shown in  FIG. 2  according to an exemplary embodiment of the present invention. The response time compensating part  14  and the gamma correcting part  15  include a first frame memory  14   a,  a second frame memory  14   b,  a comparator  14   c,  a response time compensation factor storing unit  14   d,  a response time compensation performing unit  14   e,  a third frame memory  15   a,  a gamma correction factor storing unit  15   b,  and a gamma correction performing unit  15   c.    
      The first frame memory  14   a  and the second frame memory  14   b  store pixel data of plural pixels composing a video in units of frames. That is, the fist frame memory  14   a  and the second frame memory  14   b  store the pixel data of two consecutive frames, (hereinafter, referred to as “a first frame” and “a second frame”), respectively. The comparator  14   c  compares the pixel data of the first and second frames stored in the first frame memory  14   a  and the second frame memory  14   b  between pixels at the same location and then outputs a difference between the pixel data.  
      In the response time compensation factor storing unit  14   d  are stored response-time compensation factors corresponding to the difference between pixel data of two frames in the form of a table. The response time compensation performing unit  14   e  compensates a frame preceding in time, that is, the pixel data of the first frame based on the response time compensation factor corresponding to the difference between the pixel data in the first and second frames outputted from the comparator  14   c  by referring to the response time compensation factor storing unit  14   d.    
      For example, if the pixel data of the first frame to be corrected for a certain pixel has a gray scale of 128, the pixel data of the second frame for that pixel has a gray scale of 100, and the response-time compensation factor corresponding to the difference, that is a gray scale of 28, between the pixel data of the two frames has a gray scale of 10, the response-time compensation performing unit  14   e  adds the response-time compensation factor to the pixel data of the first frame to output pixel data having a gray scale of 138.  
      Meanwhile, the third frame memory  15   a  stores the pixel data compensated by the response time compensation performing unit  14   e  in units of frames. The gamma correction factor storing unit  15   b  stores gamma correction factors corresponding to pixel data in the form of a table. The gamma correction performing unit  15   c  corrects corresponding pixel data based on the gamma correction factor corresponding to the pixel data stored in the third frame memory  15   a  by referring to the gamma correction factor storing unit  15   b.    
       FIG. 3  is a schematic block diagram illustrating a configuration of a video processing apparatus  100  according to a second exemplary embodiment of the present invention. As shown in  FIG. 3 , the video processing apparatus  100  includes a signal receiving part  110 , a decoding part  120 , a scaling part  130 , a correcting part  140 , and a displaying part  150 . The signal receiving part  110  tunes and receives the video signal from the broadcasting station or the like in accordance with a frequency corresponding to a channel selected by a user. The decoding part  120  decodes the video signal received by the signal receiving part  110  and outputs the decoded video signal to the displaying part  150  as a video signal of a type which can be displayed on the displaying part  150 . The scaling part  130  adjusts resolution of the video signal decoded by the decoding part  120  based on the user&#39;s setting and a characteristic of the display unit  150 .  
      The correcting part  140  performs a response time compensation operation to compensate a response time delay caused by the characteristic of the display unit  150  such as an LCD or the like, and a gamma correction operation to correct an error caused by a difference between the strength and the brightness (or luminance) of the video signal. In this exemplary embodiment, the correcting part  140  corrects a characteristic such as a gray-to-gray response time in the LCD. Further, the correcting part  140  performs the correction so as to overcome a problem that colors in regions of low brightness and/or medium brightness are distorted since a gamma characteristic (or gamma curve) of the LCD does not correspond to a standard gamma characteristic. The correcting part  140  performs the response-time compensation and the gamma correction simultaneously, thus shortening a time required for the video processing, simplifying a circuit configuration and hence reducing production costs.  
      The displaying part  150  displays the video based on the corrected video signal. In this exemplary embodiment, the displaying part  150  includes an LCD.  
       FIG. 4  is a block diagram illustrating a detailed configuration of the correcting part  140  in the video processing apparatus  100  of  FIG. 3 , according to an exemplary embodiment of the present invention. As shown in  FIG. 4 , the correcting part  140  includes a first frame memory  141 , a second frame memory  142 , a comparator  143 , a response time compensation factor storing unit  144 , a gamma correction factor storing unit  145 , and a correction performing unit  146 .  
      In the first frame memory  141  and the second frame memory  142  are stored pixel data in the unit of frame. More specifically, in the first frame memory  141  and the second frame memory  142  are stored the pixel data for each pixel of two consecutive frames, (hereinafter, referred to as “a first frame” and “a second frame”), respectively. In this exemplary embodiment, the second frame memory  142  stores the pixel data later by one frame than the pixel data stored in the first frame memory  141 . Hereafter, the pixel data stored in the first frame memory  141  and the second frame memory  142  will be also referred to “first pixel data” and “second pixel data,” respectively. In this exemplary embodiment, the first frame memory  141  and the second frame memory  142  are examples of a “first frame storing unit” and a “second frame storing unit,” respectively.  
      The comparator  143  compares the first pixel data and the second pixel data stored in the first frame memory  141  and the second frame memory  142 , respectively, between pixels in the same location and outputs a difference between the first and second pixel data. The response time compensation factor storing unit  144  stores response time compensation factors corresponding to the difference between pixel data of two frames in the form of a table. The response time compensation factors may be experimentally determined and stored in the response time compensation factor storing unit  144 .  
      The gamma correction factor storing unit  145  stores gamma correction factors corresponding to pixel data in the form of a table. For example, if the pixel data has a gray scale of 256, the gamma correction factors corresponding to levels of the gray scale of 256 can be stored in the gamma correction factor storing unit  145 .  
      The correction performing unit  146  corrects the first pixel data by simultaneously applying the response-time compensation factor corresponding to the difference between the first and second pixel data outputted from the comparator  143  by referring to the response time compensation factor storing unit  144  and the gamma correction factor corresponding to the first pixel data stored in the first frame memory  141  by referring to the gamma correction factor storing unit  15   b.    
      For example, if the first pixel data for a certain pixel has a gray scale of 128, the second pixel data has a gray scale of 100, the response-time compensation factor corresponding to a difference, which is a gray scale of 28, between the first and second pixel data has a gray scale of 10, and the gamma correction factor corresponding to the first pixel data having a gray scale of 128 has a gray scale of 5, the correction performing unit  146  outputs a gray scale of 143 (=128+10+5) as pixel data corrected for the first pixel data by applying the response time compensation factor(=10) and the gamma correction factor(=5) to the first pixel data(=128).  
      As an alternative, if the first pixel data for a certain pixel has a gray scale of 100, the second pixel data has a gray scale of 128, the response time compensation factor corresponding to a difference, which is a gray scale of −28, between the first pixel data and the second pixel data has a gray scale of −10, and the gamma correction factor corresponding to the first pixel data having a gray scale of 100 has a gray scale of −3, the correction performing unit  146  outputs a gray scale of 87 (=100−10−3) as pixel data corrected for the first pixel data by applying the response time compensation factor(=−10) and the gamma correction factor(=−3) to the first pixel data(=100).  
      The comparator  143  and the correction performing unit  146  may be implemented by a hardware such as a logic circuit or a computer program (software) executed by a microprocessor such as a central processing unit (CPU).  
      The video processing apparatus according to this exemplary embodiment can perform the response time compensation and the gamma correction at once through one integrated process by employing two frame memories, instead of two separate processes that need three frame memories, thereby shortening a time to process a video and simplifying a circuit configuration. Accordingly, production costs can be reduced.  
      In particular, the one integrated process required for two frame memories can reduce one frame in a delay time as compared the two separate processes required for three frame memories.  
       FIG. 5  is a flow chart illustrating a video processing method according to an exemplary embodiment of the present invention. First, response-time compensation factors to be used to compensate a response time of, for example, an LCD are stored in a predetermined memory at operation S 101 . The response-time compensation factors are determined to correspond to differences between the pixel data for each pixel of two consecutive frames. Further, gamma correction factors to be used for gamma correction of the LCD are stored in a predetermined memory at operation S 102 . The gamma correction factors are determined to correspond to gray scales of the pixel data.  
      Next, pixel data of consecutive two frames are stored in predetermined memories, respectively at operation S 103 . Subsequently, a response-time compensation factor corresponding to a difference between the pixel data of the two consecutive frames among the stored response correction factors is determined at operation S 104 . Further, a gamma correction factor corresponding to the pixel data to be corrected among the stored gamma correction factors is determined at operation S 105 . Finally, the pixel data is corrected by simultaneously applying the determined response-time compensation factor and the determined gamma correction factor at operation S 106 .  
      As described above, the exemplary embodiment of the present invention provides a video processing apparatus and a video processing method which is capable of reducing a delay time for video display and lowering production costs.  
      Although a few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.