Abstract:
An image display device is presented to solve problems of high power consumption, insufficient contrast, image flicker, and distortion of image display devices. The image display device includes an image display management module which includes a backlight control unit. The backlight control unit includes an image brightness analyzer, generating a brightness value according to an input image data; a weight generator, generating a weight according to the brightness value; an image variation analyzer, analyzing the input image data to generate an image variance; and a backlight factor generator, coupled to the weight generator and the image variation analyzer to generate a backlight adjusting signal according to the weight and the image variance. By the backlight adjusting signal, the image display device achieves the power-saving and contrast enhancement effects.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an image display device and method, and more particularly, to a liquid crystal display device and method. 
         [0003]    2. Description of the Prior Art 
         [0004]    Liquid crystal displays (LCDs) are widely implemented in various electronic products such as computers, portable computers, and televisions. Conventional LCDs have two significant defects, namely, the high power consumption and the insufficient contrast. In electronic product, the power consumed by the LCD amounts to 30% to 70% of the total power consumption, and a backlight device therein is the most power-consuming. Therefore, a power-saving backlight device is needed to provide an LCD of lower power consumption. The problem of insufficient contrast is particularly obvious when the LCD displays a dark image. The image is too dark to form a contrast with the backlight. Therefore, an LCD capable of maintaining the contrast when the image is dark is needed. 
         [0005]    In order to solve the above problems, in a prior art, an image display having a backlight control is provided, which achieves the control of the backlight according to an average brightness value and a maximum brightness value of the input image information. However, the image displayed by the front panel is not adjusted in the prior art, so the contrast extent is still insufficient. Moreover, the image analysis in the backlight control device is too simple so that the analyzed information cannot represent features of the input image information. In another prior art, a brightness histogram of an input image is generated according to the input image information and is then used to adjust the backlight, for solving the defects in analysis of the above prior art. Although this analysis may over the defects of the above art, it is still unable to actually show features of the input image. Moreover, the way of merely using the histogram in the analysis readily causes flicker of the adjusted image or distorts the image. 
         [0006]    Therefore, an image display device is needed to solve the above problems of high power consumption, insufficient contrast, image flicker, and distortion. 
       SUMMARY OF THE INVENTION 
       [0007]    In order to solve the above problems, the present invention provides an image display management module, which includes a backlight control unit. The backlight control unit includes an image brightness analyzer, generating a brightness value according to an input image data; a weight generator, generating a weight according to the brightness value; an image variation analyzer, analyzing the input image data to generate an image variance; and a backlight factor generator, coupled to the weight generator and the image variation analyzer to generate a backlight adjusting signal according to the weight and the image variance. 
         [0008]    The present invention provides a method for compensating an input image data. The method includes the following steps. An image brightness analyzer determines a brightness value of the input image data. A weight generator generates a weight for the brightness value. An image variation analyzer analyzes the input image data to generate an image variance. A backlight factor generator generates a backlight adjusting signal according to the histogram weight and the image variance. A compensated image output is generated according to the backlight adjusting signal and an image data from an image control unit. 
         [0009]    The present invention provides an image display management module, which includes an image control unit. The image control unit includes a low-pass filter, for blurring an input image data; a gain factor selector, coupled to the low-pass filter to determine a gain factor; and an output data generator, coupled to the gain factor selector to generate an output image data. 
         [0010]    The present invention provides a method for compensating an input image data. The method includes the following steps. A low-pass filter blurs an input image data. A gain factor selector determines a gain factor according to the blurred input image data. An output data generator generates an output image data according to the gain factor and the input image data. A compensated image output is generated according to the output image data and a backlight adjusting signal from a backlight control unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic view of an image display management module according to the present invention; 
           [0012]      FIGS. 2   a  to  2   d  are histograms of a brightness signal according to the present invention; 
           [0013]      FIG. 3  is a flow chart of a method for calculating a backlight adjusting signal according to the present invention; 
           [0014]      FIG. 4  is a schematic view of another image display management module according to the present invention; 
           [0015]      FIG. 5  is a flow chart of a method for calculating an output image data according to the present invention; and 
           [0016]      FIG. 6  is a schematic view of another image display management module according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The present invention will be described comprehensively hereinafter with reference to the accompanying drawings illustrating the specific embodiments of the present invention. However, the present invention should not be considered as limited to the specific embodiments. More correctly, the specific embodiments are provided to thoroughly and completely disclose the content of the present invention, and fully convey the scope of the present invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are enlarged for clarity. Like numbers refer to like elements appearing in all the drawings. The term “and/or” in the present invention includes any and all combinations of one or more of the associated items. 
         [0018]    The terminology used herein is used for describing particular specific embodiments only and is not intended to limit the scope of the present invention. The singular forms “a,” “an” and “the” in the present invention include the plural forms as well, unless other circumstances are clearly indicated. It should be further understood that the terms “comprise” and/or “include” when used in this specification, specify the presence of the features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0019]    It will be understood that when an element of a layer or region is referred to as being “on” or “extending onto” another element, it may be directly on or directly extending onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “directly extending onto” another element, no intervening element exists. It will also be understood that when an element is referred to as being “connected to” or “coupled to” another element, it may be directly connected or coupled to another element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected to” or “directly coupled to” another element, no intervening element exists. 
         [0020]    It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below may be referred to as a second element, component, region, layer, or section without departing from the principles of the present invention. 
         [0021]    In addition, relative terms, for example, “lower”, “bottom”, or “horizontal” and “upper”, “top”, or “vertical” may be used herein to describe one element&#39;s relationship to another element as illustrated in the drawings. It will be understood that the relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over, elements described as at a “lower” side of other elements would then be oriented at an “upper” side of the other elements. Thus, the exemplary term “lower” may encompass both “lower” and “upper” orientations depending on the particular orientation of the drawings. Similarly, if the device in one of the drawings is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. Thus, the exemplary term “below” or “beneath” may encompass both orientations of above and below. 
         [0022]    Specific embodiments of the present invention are described herein with reference to sectional view of ideal specific embodiments of the present invention. As such, it may be expected that the shapes may vary according to manufacturing techniques and/or tolerances. Therefore, specific embodiments of the present invention should not be construed as limitations to the particular shapes of regions illustrated in the present invention, but should be construed to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as a cone-shaped region usually has a circular vertex and rough and/or nonlinear features. Thus, the regions in the figures are illustrated for exemplifying instead of being interpreted as an accurate shape to limit the scope of the present invention. In addition, terms such as “horizontal” and “vertical” refer to general directions or relationships besides the exact orientations of 0 degree or 90 degrees. 
         [0023]    Unless additionally defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art, and will not be interpreted in an ideal or overly formal sense unless clearly defined herein. 
         [0024]      FIG. 1  is a schematic view of an image display management module  100  according to the present invention. The image display management module  100  includes a backlight control unit  110 . The backlight control unit  110  includes an image brightness analyzer which is implemented by a histogram generator  101  in this embodiment, a weight generator  102 , an image variation analyzer  103 , and a backlight factor generator  104 . The histogram generator  101  is connected to the weight generator  102 , and the weight generator  102  is connected to the backlight factor generator  104 , while the image variation analyzer  103  is similarly connected to the backlight factor generator  104 . 
         [0025]    The histogram generator  101  in the backlight control unit  110  generates a histogram value H according to an input image data I and transfers the histogram value H to the weight generator  102 . The weight generator  102  calculates a weight W according to the histogram value and transfers the weight W to the backlight factor generator  104 . The image variation analyzer  103  generates an image variance Var according to the input image data I and similarly transfers the image variance Var to the backlight factor generator  104 . The backlight factor generator  104  then generates a backlight adjusting signal BL according to the received weight W and image variance Var. The image display management module  100  may directly display the backlight according to the backlight adjusting signal BL transferred to a display  130 , thereby managing the image display through the backlight adjustment, or transfer the backlight adjusting signal BL after being processed by an image control unit  120  to the display  130 . 
         [0026]    The input image data is usually composed of signals of red, green, and blue colors. The intensity of signals of each color is divided into 256 gray levels. For any input frame, histograms may be generated for signals of three colors respectively.  FIGS. 2   a ,  2   b , and  2   c  are respectively histograms of three colors. A brightness signal Y and chromaticity signal U and V of the frame may be obtained by signals of three colors. The brightness signal Y and chromaticity signal U and V may be calculated based on the following equations: 
         [0000]        Y= 0.229 *R+ 0.587 *G+ 0.114 *B    
         [0000]        U=− 0.147 *R− 0.289 *G+ 0.437 *B    
         [0000]        V= 0.615 *R− 0.515 *G− 0.1 *B    
         [0027]    The brightness signal Y may also be divided into 256 gray levels. As such, a histogram  2   d  of the brightness signal may be obtained. The weight generator  102  may calculate the weight W according to the histogram of the brightness signal. 
         [0028]    The backlight adjusting signal BL is adjusted based on the following principle. When the image is dark or the gray level distribution is narrow, the brightness of the backlight is adjusted lower. When the image is bright or the image contains bright and dark portions or has a uniform gray level distribution, the brightness of the backlight is adjusted higher. Since the histograms of the image only roughly show the brightness distribution of the image, the variation of the brightness distribution of the image needs to be further calculated.  FIG. 3  is a flow chart  300  of a method for calculating a backlight adjusting signal BL according to the present invention. First, in Step  301 , an image variance Var of an input image data I is calculated based on Equation 1. 
         [0000]    
       
         
           
             
               
                 
                   
                     Var 
                     = 
                     
                       
                         1 
                         
                           M 
                           × 
                           N 
                         
                       
                        
                       
                         
                           ∑ 
                           
                             i 
                             = 
                             1 
                           
                           M 
                         
                          
                         
                           
                             ∑ 
                             
                               j 
                               = 
                               1 
                             
                             N 
                           
                            
                           
                             
                               [ 
                               
                                 
                                   I 
                                    
                                   
                                     ( 
                                     
                                       i 
                                       , 
                                       j 
                                     
                                     ) 
                                   
                                 
                                 - 
                                 
                                   I 
                                   _ 
                                 
                               
                               ] 
                             
                             2 
                           
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   where 
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   1 
                 
               
             
             
               
                 
                   
                     I 
                     _ 
                   
                   = 
                   
                     
                       1 
                       
                         M 
                         × 
                         N 
                       
                     
                      
                     
                       
                         ∑ 
                         
                           i 
                           = 
                           1 
                         
                         M 
                       
                        
                       
                         
                           ∑ 
                           
                             j 
                             = 
                             1 
                           
                           N 
                         
                          
                         
                           I 
                            
                           
                             ( 
                             
                               i 
                               , 
                               j 
                             
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   2 
                 
               
             
           
         
       
     
         [0000]    where M×N represents a size of the image, and I(i, j) represents a position of every pixel in the image. In Step  302 , a brightness value H of the input image data I is calculated. Then, in Step  303 , a weight W of the brightness value H is generated based on Equation 3, in which the image backlight minimum W min  is a predetermined value. 
         [0000]    
       
         
           
             
               
                 
                   
                     W 
                     = 
                     
                       
                         
                           
                             ( 
                             
                               1 
                               - 
                               
                                 W 
                                 min 
                               
                             
                             ) 
                           
                           × 
                           
                             I 
                             _ 
                           
                         
                         255 
                       
                       + 
                       
                         W 
                         min 
                       
                     
                   
                    
                   
                     
 
                   
                    
                   and 
                    
                   
                     
 
                   
                    
                   
                     W 
                     ∈ 
                     
                       [ 
                       
                         0.7 
                         , 
                         1 
                       
                       ] 
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   3 
                 
               
             
           
         
       
     
         [0029]    In Step  304 , the image variance Var is compared with a product of an image variation threshold V th  and the weight W to see if the image variance Var is larger than the product, and if so, Step  305  is performed to confirm that the backlight adjusting signal BL is the weight W. Otherwise, Step  306  is performed to confirm that the backlight adjusting signal BL is a function of the weight W and the image variance Var. The function may be expressed by Equation 4, where the image variation threshold V th  is a predetermined value. 
         [0000]    
       
         
           
             
               
                 
                   
                     g 
                      
                     
                       ( 
                       
                         W 
                         , 
                         Var 
                       
                       ) 
                     
                   
                   = 
                   
                     W 
                     - 
                     
                       
                         ( 
                         
                           
                             
                               V 
                               th 
                             
                             × 
                             W 
                           
                           - 
                           Var 
                         
                         ) 
                       
                       
                         3 
                         × 
                         
                           V 
                           th 
                         
                         × 
                         W 
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   4 
                 
               
             
           
         
       
     
         [0030]    It can be seen from the result of the process  300  that when the variation of the input image data I is small, the backlight adjusting signal BL is smaller than the weight W. When the variation of the input image data I is large, the backlight adjusting signal BL is approximately equal to the weight W. Therefore, the image display management module  100  adjusts the brightness of the backlight lower to reduce the power consumption when the brightness distribution of the input image is uniform, and adjusts the brightness of the backlight higher to enhance the contrast when the variation of the brightness distribution of the image is large, so as to avoid the flicker effect. 
         [0031]      FIG. 4  is a schematic view of an image display management module  400  according to the present invention. The image display management module  400  includes an image control unit  420 . The image control unit  420  includes a low-pass filter  405 , a gain factor selector  406 , and an output data generator  407 . The low-pass filter  405  is connected to the gain factor selector  406  which is connected to the output data generator  407 . 
         [0032]    The low-pass filter  405  in the image control unit  420  filters high frequencies in an input image data I. In other words, the filtered image data of the input image data I is blurred and formed an ambient image data A. This may reduce the amount of the data to be processed and may process the image data sensitive to the backlight. After the ambient image data A is transferred from the low-pass filter  405  to the gain factor selector  406 , the gain factor selector  406  may determine a gain factor f according to the ambient image data A by the logic of the method illustrated in  FIG. 4 . The gain factor f is transferred from the gain factor selector  406  to the output data generator  407 . The output data generator  407  then generates an output image data RecI according to the gain factor f. The image display management module  400  transfers the output image data RecI to a display, such that the display may display the image according to the output image data RecI. 
         [0033]      FIG. 5  is a flow chart  500  of a method for calculating an output image data RecI according to the present invention. In Step  501 , an input image data I obtains an ambient image data A by a low-pass filter  405 . In Step  502 , a gain factor selector  406  calculates a gain factor f according to ambient image data A based on Equation 5, in which an image variation threshold A 0 is a predetermined value. 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         f 
                         = 
                           
                          
                         
                           
                             
                               
                                 
                                   F 
                                   max 
                                 
                                 - 
                                 
                                   F 
                                   min 
                                 
                               
                               
                                 
                                   A 
                                   min 
                                 
                                 - 
                                 
                                   A 
                                   0 
                                 
                               
                             
                             × 
                             
                               A 
                                
                               
                                 ( 
                                 
                                   i 
                                   , 
                                   j 
                                 
                                 ) 
                               
                             
                           
                           + 
                         
                       
                     
                     
                       
                           
                          
                         
                           
                             if 
                              
                             
                                 
                             
                              
                             
                               A 
                                
                               
                                 ( 
                                 
                                   i 
                                   , 
                                   j 
                                 
                                 ) 
                               
                             
                           
                           &lt; 
                           
                             A 
                             0 
                           
                         
                       
                     
                   
                   
                     
                       
                           
                          
                         
                           
                             
                               
                                 F 
                                 min 
                               
                               × 
                               
                                 A 
                                 min 
                               
                             
                             - 
                             
                               
                                 F 
                                 max 
                               
                               × 
                               
                                 A 
                                 0 
                               
                             
                           
                           
                             
                               A 
                               min 
                             
                             - 
                             
                               A 
                               0 
                             
                           
                         
                       
                     
                     
                         
                     
                   
                   
                     
                       
                         = 
                           
                          
                         
                           F 
                           min 
                         
                       
                     
                     
                       
                           
                          
                         
                           
                             if 
                              
                             
                                 
                             
                              
                             
                               A 
                                
                               
                                 ( 
                                 
                                   i 
                                   , 
                                   j 
                                 
                                 ) 
                               
                             
                           
                           ≥ 
                           
                             A 
                             0 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   5 
                 
               
             
           
         
       
     
         [0000]    where F min  and F max  are defined as: 
         [0000]    
       
         
           
             
               F 
               min 
             
             = 
             
               
                 
                   255 
                   × 
                   BL 
                 
                 
                   I 
                   max 
                 
               
               &lt; 
               1 
             
           
         
       
       
         
           
             
               F 
               max 
             
             = 
             
               
                 2 
                 - 
                 
                   F 
                   min 
                   
                     1 
                     / 
                     4 
                   
                 
               
               &gt; 
               1 
             
           
         
       
     
         [0034]    In Step  503 , a maximum of the input image data I is compared with a product of 255 and the backlight adjusting signal BL to see if the maximum is less than or equal to the product, and if so, Step  504  is performed to confirm that the output image data RecI is the input image data I divided by the backlight adjusting signal BL. Otherwise, the Step  505  is performed to confirm that the output image data RecI is a product of the input image data I and the gain factor f divided by the backlight adjusting signal BL. Based on the calculation of the process  500 , the output image data RecI may be adjusted according to the intensity of the backlight adjusting signal BL, thereby avoiding the saturation of extremely dark and bright places in the image to distort the image. 
         [0035]      FIG. 6  is a schematic view of an image display management module  600  according to the present invention. The image display management module  600  includes a backlight control unit  610  and an image control unit  620  as described above. The backlight control unit  610  is connected to an output data generator  607  of the image control unit  620  via a backlight factor generator  604 . Thus, the output data generator  607  calculated an output image data RecI according to a gain factor f and a backlight adjusting signal BL. The image display management module  600  transfers the output image data RecI and the backlight adjusting signal BL to a display, such that the backlight of the display is displayed according to the backlight adjusting signal BL and the image displayed by a front panel is the output image data RecI. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
         
           
               100  image display management module 
               101  histogram generator 
               102  weight generator 
               103  image variation analyzer 
               104  backlight factor generator 
               110  backlight control unit 
               120  image control unit 
               130  display 
               400  image display management module 
               405  low-pass filter 
               406  gain factor selector 
               407  output data generator 
               420  image control unit 
               430  display 
               600  image display management module 
               604  backlight factor generator 
               607  output data generator 
               610  backlight control unit 
               620  image control unit 
             A ambient image data 
             BL backlight adjusting signal 
             f gain factor 
             H histogram value 
             I input image data 
             RecI output image data 
             Var image variance 
             W weight