KR100860993B1 - Image display apparatus and method thereof - Google Patents

Abstract

The present invention changes the luminance weight of each subfield during image display while suppressing deterioration of image quality such as flicker, so that one frame of the image signal is composed of a plurality of subfields. An image display apparatus for controlling light emission or non-emission light emission, and for multi-gradation display, comprising: a table storage unit for storing a plurality of luminance weight tables having luminance weights assigned to respective subfields, and analyzing image signals and corresponding characteristics of image signals. An image analyzer which selects one luminance weight table, and a table output unit which reads out the selected luminance weight table from the table storage unit, and outputs the table output unit, wherein the table output unit is assigned to each subfield when the selection of the luminance weight table is converted. The luminance weight to be allocated is the luminance weight of the newly selected luminance weight table from the luminance weight of the previously selected luminance weight table. Outputs one or more transition luminance weight tables that are determined to transition in stages to the gage.

Description

Image display device and image display method {IMAGE DISPLAY APPARATUS AND METHOD THEREOF}

1 is a diagram illustrating a configuration of an image display device according to a first embodiment of the present invention.

2 is a diagram illustrating a configuration of a table output circuit according to the first embodiment of the present invention.

3 is a diagram illustrating an example of a luminance weight table and a transition luminance weight table generated by the table output circuit according to the first embodiment of the present invention.

4 is a graph showing changes in luminance weight as an example of the luminance weight table and the transition luminance weight table shown in FIG. 3.

FIG. 5 is a graph showing a change in luminance observed from the user's time when the number of gradations is changed from 128 to 256 gradations by changing the weight table when the luminance 100 is displayed.

FIG. 6 is a graph showing a change in luminance observed from the user's time when the number of gradations is changed from 256 to 128 gradations by changing the weight table when the luminance 100 is displayed.

7 is a diagram illustrating an example of a small light emission pattern of a non-light emitting subfield by WTB.

8 is a diagram illustrating an example of a small light emission pattern of a non-light emitting subfield by WTA.

9 is a graph illustrating an example of luminance distribution by WTB (256 gray scales).

10 is a graph illustrating an example of luminance distribution by WTA (128 gradations).

11 is a diagram illustrating an example of a luminance weight table WTA 'having luminance weight with reduced ubiquity.

12 is a graph showing luminance weight SFW of each subfield SF of WTA, WTB, and WTA '.

FIG. 13 is a diagram illustrating an example of a small light emission pattern of a non-light emitting subfield by WTA ′. FIG.

Fig. 14 is a graph showing an example of luminance distribution by WTA '(about 128 gradations with reduced locality).

15 is a diagram illustrating another example of the luminance weight table and the transition luminance weight table generated by the table output circuit according to the first embodiment of the present invention.

FIG. 16 is a graph showing changes in luminance weight as an example of the luminance weight table and the transition luminance weight table shown in FIG. 15.

<Explanation of symbols for the main parts of the drawings>

100. . Image display device 110. . Table output circuit

111. . Table storage 11la. . Luminance weight table

11 lb. . Transition luminance weight table group 112. . Image analyzer

113. . Table output 114. . Table holding part in use

120. . Light emission pattern control circuit 130. . Plasma display

The present invention relates to an image display apparatus and an image display method.

An image display device that displays an image by binary control of emission and non-emission, for example, a plasma display device or the like, generally displays one frame of an image by dividing it into a plurality of subfields (SF). By doing so, images are displayed by a so-called subfield method which performs multi-gradation display. According to this subfield method, gray scale display is performed by dividing the time of one frame into a plurality of subfields, and assigning a weight indicating the number of light emission or the amount of light emission to each of the plurality of subfields and combining the subfields to emit light. . The weight assigned to this subfield is called luminance weight (Sub Field Weight: SFW).

When each one frame is divided into eight subfields SF1 to SF8, the luminance weight of (1, 2, 4, 8, 16, 32, 64, 128) is assigned to each subfield, for example. Each subfield includes an address period (write period) for writing data for whether or not to emit light for each pixel, and a sustain period (hold period) for emitting all of the pixels to which data to be emitted are simultaneously written. By combining these subfields to emit light, 256 gray levels from 0 to 255 gray levels are displayed. For example, when 11 gray levels (luminance 11) are displayed, SF1, SF2, SF4 having luminance weights "1", "2", and "8" respectively emit light.

Incidentally, the number of gray scale steps (hereinafter, referred to as the gray scale number) is the number of types of the sum total of the luminance weights of the subfields to be emitted. In the above example, the sum of the luminance weights by the combination of the subfields to be emitted is, for example, 256 types of (0, 1, 2, 3, 4, ..., 254, 255). Therefore, the number of gradations is 256.

In an image display device which displays multi-gradation using such a subfield method, it is known that a phenomenon in which image quality deteriorates and is observed during moving picture display occurs. One of the causes is a so-called pseudo pseudo outline in which an image of a false image which is not present in the image display device displaying a moving image is observed when observed along a place where light is not emitted. For this video pseudo contour, detailed description thereof will be omitted.

In order to reduce the occurrence of such pseudo contours in the video, the number of subframes is increased and the number of subfields is increased without changing the number of gray scales. The luminance weight assigned to each subfield by increasing the number of subfields is increased. Becomes less. Therefore, since the non-light-emitting subfields can be reduced when displaying the same gradation, generation of video pseudo contours can be reduced. In addition, although the number of gradations is reduced, if only the issuance pattern of the non-light-emitting subfield is used for gradation display, the performance of reducing the pseudo pseudo contour is improved. Furthermore, when various image processing methods, such as a dither method, are used, the position of the non-light-emitting sub-fields may be dispersed, thereby improving the performance of reducing video pseudo contours. However, according to the image processing method for reducing the occurrence of the moving image pseudo outline as described above, there is a sense of noise that the image is observed while being displayed when the moving image is displayed.

Therefore, in order to suppress the noise of the video, the number of subfields per frame is increased without changing the number of gray levels as described above, or the number of gray fields is reduced without changing the number of subfields, and the number of gray levels for the number of subfields is changed. Need to be reduced. However, if the number of subfields is large, the number of drivers needs to be increased, resulting in increased cost. In addition, reducing the number of tones decreases the resolution of a still image, resulting in deterioration of image quality.

As described above, in order to improve the image quality of the image display device, there are three factors to be solved: "reduction of video pseudo contour", "removal of noise in video", and "improvement of gradation number".

In addition, as a method of reducing the occurrence of such a moving image pseudo outline, improvement such as changing the order of distributing luminance weight is made. For example, Japanese Patent Laid-Open No. 2003-177708 discloses distributing a small luminance weight to subfields between subfields to which a large luminance weight is assigned. Japanese Laid-Open Patent Publication No. 2006-1495329 discloses a luminance weight between adjacent subfields such that the difference between the last subfield and the luminance weight of the immediately preceding subfield is maximized, and the subfields that are adjacent to the previous subfield become the maximum subfield. It is disclosed to assign the luminance weight so that the difference is small.

However, in the conventional image display apparatus, since the luminance weight assigned to each subfield was fixed when the images were continuously displayed, the "gradation number" that can be displayed was also fixed. The number of gray levels has been determined to reduce the occurrence of video pseudo contours and to increase the number of gray levels. Therefore, according to the conventional image display apparatus, since the maximum number of gray scales for reducing the occurrence of the moving image pseudo outline is set, there is a problem that the feeling of noise in the moving image cannot be removed.

Also, in order to eliminate the noise in a moving image, when trying to change the "gradation number" while displaying an image continuously, that is, when trying to change the luminance weight of each subfield, the image is observed as an adult. flicker) and the like, and the image quality deteriorates. In addition, in the conventional image display apparatus, when the user or the like changes the image mode, the number of gradations is changed after the display of the continuous image is once stopped or stopped, and thus the image quality cannot be improved while the images are continuously displayed. There was. In the following description, changing the number of tones when displaying images continuously is referred to as a "dynamic conversion method", and changing the number of tones by temporarily stopping or stopping the display of an image is called a "static conversion method". It is called.

This invention is made | formed in view of the said problem, The objective of this invention is the novel thing which can change the brightness weight of each subfield during image display, suppressing deterioration of image quality, such as a fricker. An improved image display device and an image display method are provided.

In order to solve the above problems, according to an aspect of the present invention, one frame of an image signal is composed of a plurality of subfields having different luminance weights, and an image for performing multi-gradation display by emitting or non-emission control of each subfield. A display device, comprising: a table storage unit for storing a plurality of luminance weight tables in which a luminance weight assigned to each subfield is determined; an image signal is analyzed, and among the plurality of luminance weight tables, one luminance corresponding to the characteristics of the image signal. An image analyzer which selects a weight table, and a table output unit which reads the luminance weight table selected by the image analyzer from the table storage unit and outputs the read luminance weight table, the table output unit comprising luminance by the image analyzer When the selection of the weight table is converted, the luminance weight assigned to each subfield is the previously selected luminance weight table. An image display apparatus is provided, which outputs one or two or more transition luminance weight tables that are determined to gradually transition from the luminance weight of the table to the luminance weight of the newly selected luminance weight table.

According to this configuration, the image analyzing unit analyzes the image signal, extracts the feature of the image signal, and selects the luminance weight table corresponding to this feature. The table output unit first outputs one or two or more transition luminance weight tables when the selected luminance weight table and the currently used luminance weight table are different from each other. Further, the table output unit outputs the transition luminance weight table, and then reads the newly selected luminance weight table from the table storage unit and outputs it. Therefore, the image display device can perform light emission by assigning the luminance weight to each subfield based on the luminance weight table or the transition luminance weight table outputted from this table output unit. Thus, the image display device can gradually shift the luminance weight of each subfield used for light emission step by step.

The table output unit may also sequentially output the plurality of transition luminance weight tables for each predetermined number of frames. According to this configuration, when the luminance weight table is converted, the table output unit sequentially outputs the transition luminance weight table for every predetermined number of frames, outputs the plurality of transition luminance weight tables, and then outputs the newly selected luminance weight table. Therefore, the image display device can gradually shift the luminance weight of each subfield used for light emission step by step.

The plurality of luminance weight tables may also include a low gradation display luminance weight table corresponding to the low gradation display of the image signal, and a high gradation display luminance weight table corresponding to the high gradation display of the image signal. According to this configuration, the image display device can perform low gradation display and low gradation display by distributing the luminance weight to each subfield based on the low gradation display luminance weight table, and the luminance weight for high gradation display. By distributing the luminance weight to each subfield based on the table, high gradation display and high gradation display can be performed.

The image analyzing unit may select the low gradation display luminance weight table when the image signal represents a moving picture, and select the high gradation display luminance weight table when the image signal represents a still image. According to this structure, low gradation display can be performed when displaying moving images, and high gradation display can be performed when displaying still images.

In addition, the image analyzing unit may select the low gradation display luminance weight table or the high gradation display luminance weight table according to the luminance distribution indicated by the image signal. According to this configuration, the low gradation display and the high gradation display can be switched in accordance with the luminance distribution of the image.

The plurality of luminance weight tables may include a low luminance luminance weight table corresponding to the low luminance distribution of the image signal and a luminance luminance table for the full luminance corresponding to the luminance distribution of the image signal.

In addition, the image analyzing unit may select the low luminance luminance weight table or the full luminance luminance weight table according to the luminance distribution indicated by the image signal. According to such a configuration, the image analyzing unit selects a low luminance luminance weight table when the luminance distribution indicated by the image signal is inclined at low luminance, and when the luminance distribution represented by the image signal spans a wide range of luminance, the overall luminance distribution. Selects the luminance weight table for full brightness corresponding to. Therefore, since the appropriate luminance weight can be allocated according to many and few of the low luminance distribution, high gradation display can be performed.

The transition luminance weight table is stored in advance in the table storage unit, and the table output unit may read the transition luminance weight table from the table storage unit and output the read-out transition luminance weight table. According to this structure, the table output unit can output the transition luminance weight table.

The table output unit may generate the transition luminance weight table based on the luminance weight of the luminance weight table before and after the conversion, and output the generated transition luminance weight table. According to this structure, the table output unit can output the transition luminance weight table.

The apparatus may further include a light emission pattern control circuit that controls the light emission pattern based on the transition brightness weight table or the brightness weight table output by the brightness weight table output unit. According to this configuration, the light emission pattern control unit can control the light emission pattern for issuing the image displayed by the image signal according to the transition luminance weight table assigned to each subfield or the luminance weight of the luminance weight table.

In order to solve the above problems, according to another aspect of the present invention, an image in which one frame of an image signal is composed of a plurality of subfields having different luminance weights, and multi-gradation display is performed by emitting or non-emitting control of each subfield. A display method comprising: a first table output step of reading a luminance weight table of 1 selected from a plurality of luminance weight tables in which the luminance weights assigned to each subfield stored in the table storage unit are determined, and outputting the read luminance weight table; And a selection step of analyzing the image signal and newly selecting one luminance weight table corresponding to the characteristics of the image signal from among the plurality of luminance weight tables, and the luminance weight assigned to each subfield in the first table outputting step. The luminance weight of the newly selected luminance weight table is selected from the luminance weight of the luminance weight table. A transition table output step of outputting one or more transition luminance weight tables determined to transition step by step, and a second table output of reading the luminance weight table newly selected in the selection step and outputting the read luminance weight table; There is provided an image display method comprising the step. According to such a structure, the brightness weight of each subfield used for light emission can be gradually changed gradually.

In the transition table outputting step, the plurality of transition luminance weight tables may be sequentially output for each predetermined number of frames.

The plurality of luminance weight tables may also include a low gradation display luminance weight table corresponding to the low gradation display of the image signal, and a high gradation display luminance weight table corresponding to the high gradation display of the image signal.

In the selecting step, the low gradation display luminance weight table may be selected when the image signal represents a moving image, and the high gradation display luminance weight table may be selected when the image signal represents a still image.

Further, in the selection step, the low gradation display luminance weight table or the high gradation display luminance weight table may be selected according to the luminance distribution indicated by the image signal.

The plurality of luminance weight tables may include a low luminance luminance weight table corresponding to the low luminance distribution of the image signal and a luminance luminance table for the full luminance corresponding to the luminance distribution of the image signal.

In addition, the image analyzing unit may select the low luminance luminance weight table or the full luminance luminance weight table according to the luminance distribution indicated by the image signal.

The transition table output step may also include a read step of reading one or more transition luminance weight tables stored in the table storage unit in advance, and an output step of outputting the read luminance weight table.

The transition table outputting step may further include a generating step of generating a transition luminance weighting table based on the luminance weight of the luminance weighting table output in the first table outputting step and the luminance weight of the luminance weighting table newly selected in the selecting step. And an output step of outputting the luminance weight table.

EMBODIMENT OF THE INVENTION Preferred embodiment of this invention is described in detail, referring an accompanying drawing below. In addition, in this specification and drawing, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol about the component which has substantially the same functional structure.

(1.Configuration of the Image Display Device)

First, with reference to FIG. 1, the image display apparatus which concerns on 1st Embodiment of this invention is demonstrated. 1 is a diagram illustrating a configuration of an image display device according to a first embodiment of the present invention. As shown in FIG. 1, the image display device 100 according to the present embodiment includes a table output circuit 110, a light emission pattern control circuit 120, and a plasma display 130.

The image display apparatus 100 is an apparatus for displaying an image by receiving an input of an image signal. The image display apparatus 100 comprises a plurality of subfields of one frame of the image signal having different luminance weights, and controlling each light emission or non-emission of each subfield. It is a device for displaying. In this way, a multi-gradation display method by issuing combinations of a plurality of subfields is called a subfield method. In addition, although such an image display apparatus 100 is demonstrated below as a plasma display apparatus, this invention is not limited to such an example, for example. The present invention can be applied to all image display apparatuses for multi-gradation display using the subfield method.

In addition, the image display apparatus 100 divides one frame into ten subfields, for example, and it demonstrates below that each subfield is light emission or non-emission control. However, the present invention is not limited to this example, and one frame may be divided into a plurality of subfields other than ten.

The table output circuit 110 receives an input of an image signal, analyzes the image signal, and extracts features of the image signal. The table output circuit 110 then outputs a sub-field weight table (SFWT), which is optimal for the characteristics of the extracted image signal, to the light emission pattern control circuit 120. At this opportunity, the table output circuit 110 outputs one or two or more transition luminance weight tables sequentially when the luminance weight table newly outputted and the luminance weight table immediately outputted are different, and then outputs the corresponding new luminance weight table. Output This table output circuit 110 will be described later in detail.

In this case, the luminance weight table defines luminance weights allocated to each subfield. For example, when one frame is divided into ten subfields SF1 to SF10, one luminance weight table determines one pair of luminance weights SFW1 to SFW10 assigned to each subfield SF1 to SF10. Similar to the luminance weight table, the transition luminance weight table defines luminance weights assigned to each subfield. The transition luminance weight table is a luminance weight table for shifting the luminance weight of the luminance weight table little by little over several frames. The transition luminance weight table has, for example, a luminance weight equal to the luminance weight of each of the luminance weight tables, or a luminance weight between the luminance weights of the respective luminance weight tables.

The light emission pattern control circuit 120 receives an image signal and an input of a luminance weight table or a transition luminance weight table output from the table output circuit 110. Then, the light emission pattern control circuit 120 determines a light emission pattern for displaying a predetermined gray scale of the image signal according to the brightness weights SFW1 to SFW10 determined by the brightness weight table or the transition brightness weight table, and displays the plasma display ( 130).

The plasma display 130 displays an image based on an emission pattern output from the emission pattern control circuit 120 as an example of the display unit. However, as the display unit, the plasma display 130 includes a pixel unit including a pulse generator for generating a driving pulse or the like based on the light emission pattern and a plurality of pixels which are controlled to emit or not emit light based on the driving pulse or the like (not shown). And the like. Since this configuration is the same as a general plasma display, the detailed description thereof will be omitted. In addition, although the plasma display 130 was used as a display part, any image display part which performs multi-gradation display by the subfield method may be sufficient.

(2.Configuration of Table Output Circuit)

Next, with reference to FIG. 2, the structure of the table output circuit which concerns on 1st Embodiment of this invention is demonstrated. 2 is a diagram illustrating a configuration of a table output circuit according to the first embodiment of the present invention. As shown in FIG. 2, the table output circuit 110 includes a table storage section 111, an image analysis section 112, a table output section 113, and a table holding section 114 in use.

The table storage section 111 stores a luminance weight table group 11la having a plurality of luminance weight tables and a transition luminance weight table group 11lb having a plurality of transition luminance weight tables. The table storage unit 111 outputs a plurality of luminance weight tables or a plurality of transition luminance weight tables to the table output unit one by one.

The image analysis unit 112 analyzes an image signal included in the image signal and extracts features of the image signal. The image analyzer 112 selects a luminance weight table suitable for displaying individual images from the luminance weight table group 11la according to the characteristics of the extracted image signal, and outputs it to the table output unit 113.

The table output unit 113 is the luminance weight table newly selected by the image analysis unit 112 and the luminance weight table in use which was selected in the past by the image analysis unit 112 and stored in the table holding unit 114 in use. Take input The table output unit 113 reads the luminance weight table newly selected by the image analysis unit 112 from the table storage unit 111 and outputs it to the light emission pattern control circuit 120. The table output unit 113 also outputs the newly selected luminance weight table to the table holding unit 114 during use.

At this time, the table output unit 113 outputs the newly selected luminance weight table when the luminance weight table selected in the past and the newly selected luminance weight table are the same. However, the table output unit 113 changes the luminance weight table to be output if the luminance weight table selected in the past and the newly selected luminance weight table are different from each other. When the table output unit 113 performs this conversion, one or two or more transitions having luminance weights that gradually transition from luminance weights determined in the previously selected luminance weight table to luminance weights determined in the newly selected luminance weight table are performed. The luminance weight table is sequentially output for one or two or more frames, and then the newly selected luminance weight table is output.

In the present embodiment, the table output unit 113 outputs a newly selected luminance weight table when the luminance weight table selected in the past and the newly selected luminance weight table are the same, but the present invention is not limited to this. The table output unit 113 may not output the luminance weight table, for example, when the luminance weight table selected in the past and the newly selected luminance weight table are the same. At this time, when the light emission pattern control circuit 120 does not receive the input of the new brightness weight table, the light emission pattern control circuit 120 may continue the light emission or non-light emission control using the previously input brightness weight table.

In use, the table holding unit 114 maintains the luminance weight table that has been selected in the past by the image analyzing unit 112 and is currently used for light emission, as described above, and transfers the luminance weight table to the table output unit 113. Output

In addition, although the table weighting part 114 maintains the brightness weight table currently used for light emission, when the transition brightness weight table is used for light emission, it is also possible to hold the said transition brightness weight table.

In addition, although the table output circuit 110 includes the table holding part 114 in use which hold | maintains the brightness weight table currently used for light emission, this invention is not limited to this. The table output circuit 110 does not have the table holding part 114 in use, and the luminance weight table currently being used may be held in the table output part 113, for example. In addition, the luminance weight table currently being used may be held in, for example, the light emission pattern control circuit 120 and input to the table output unit 113.

As described above, the image display device 100 of the present embodiment displays the image by the luminance weight of the transition luminance weight table which is sequentially output from the table output circuit 110 when the luminance weight is changed, and then the new luminance weight is displayed. The image is displayed by the luminance weight of the table. Therefore, the image display device 100 suppresses display defects, such as a precursor, which may occur due to a change in the lighting period (light emission pattern) by changing the luminance weight during the continuous display of an image, and at the same time, dynamically adjusts the luminance weight. It is possible to change the. According to the image display device 100 of the present embodiment, it is possible to arbitrarily change the number of gradations and the like by an image which has not been realized so far, so that gradation display that is optimal for individual images can be realized.

(3.Example of the operation of the table output circuit)

Hereinafter, with reference to FIG. 3 and FIG. 4, each structure operation | movement of the table output circuit 110 which concerns on 1st Embodiment of this invention is concretely demonstrated to an example in detail. 3 is a diagram illustrating an example of a luminance weight table and a transition luminance weight table generated by the table output circuit 110 according to the first embodiment of the present invention. 4 is a graph showing changes in luminance weight as an example of the luminance weight table and the transition luminance weight table shown in FIG. 3. In addition, below, each subfield is called "SF1-SF10", and the luminance weight (SubWeight) SFW allocated to each subfield is called "SFW1-SFW10." The luminance weight table (SFWT) is referred to as "WT", and the transition luminance weight table is referred to as "transition WT".

The luminance weight table group 11la stored in the table storage section 111 includes a WTA that is a WT for expressing low grayscales in 128 steps and a WTB that is a WT for expressing high gray levels in 256 steps. The transition luminance weight table group 11lb includes transition WT _AB 1 to transition WT _AB 5, which is a transition WT having a luminance weight that gradually transitions from frame to frame with a luminance weight of WTB from luminance weight of WTA. Here, WTA is an example of the low gradation display luminance weight table corresponding to the low gradation display of the image signal, and WTB is an example of the high gradation display luminance weight table corresponding to the high gradation display of the image signal. In addition, the luminance weight table for displaying high gradations may be a luminance weight table for displaying high gradations of 512 steps, or may be a luminance weight table for displaying gradations of other steps. The low gradation display luminance weight table may be a luminance weight table for displaying low gray levels of 256 levels, or may be a luminance weight table for displaying gray levels of other steps.

In addition, in this embodiment, although the luminance weight table group 11la memorize | stored in the table storage part 111 contains WTA and WTB, this invention is not limited to this example. The luminance weight table group 11la may include WTs other than WTA and WTB. For example, the luminance weight table group 11la may further include a WTC or the like that is a luminance weight table for expressing high gradation in step 512. In this case, the transition luminance weight table group 11lb further includes a plurality of transition WT _ACs that determine the luminance weights that gradually transition from the luminance weights of the WTA to the luminance weights of the WTC, and the WTCs from the luminance weights of the WTB. It may include a plurality of transition WT _BCs that define the luminance weights that transition in stages with the excitation luminance weights. In this manner, the WT included in the luminance weight table group 11la can be appropriately changed depending on the performance of the image display device and the like, and it is not necessary to be WTA and WTB.

As shown in FIG. 3, the WTA has (2,4,8,12,18,26,34,42,50,59) as SFW1 to SFW10 assigned to each of SF1 to SF10, for example. For example, it has (1,2,4,8,15,25,35,45,55,65) as SFW1-SFW10. By having such SFW1 to SFW10, the WTA can display up to 128 gray levels up to (0, 2, 4, ..., 253, 255) by the combination of SF1 to SF10 which emits light. By having such SFW1 to SFW10, the WTB can display 256 gray levels up to (0, 1, 2, ..., 254, 255) by the combination of the subfields SF1 to SF10 that emit light.

The WTA can reduce the difference between the luminance weights SFW1 to SFW10 assigned to each subfield SF1 to SF10 by reducing the number of gray levels (step 128) for the number of subfields (10). Therefore, the WTA can reduce the noise of the video when displaying the video of the same gradation.

Since WTB can display still images with higher resolution than displays at low gray levels when displaying still images by increasing the number of gray scales (256 levels) for the number of subfields (10), the image quality is high. Can improve.

Transition WT _AB 1 to Transition WT _AB 5 have a luminance weight that gradually transitions from each luminance weight of WTA to each luminance weight of WTB. As shown in FIG. 3, the transition WT _AB 1 has (2,4,8,11,18,26,34,42,50,60) as SFW1 to SFW10, for example. The transition WT _AB 2 has, for example, (2,3,7,11, 17,26,34,43,51,61) as SFW1 to SFW10. The transition WT _AB 3 has, for example, (1,3,6,10,17,26,35,43,52,62) as SFW1 to SFW10. The transition WT _AB 4 has, for example, (1,3,6,9,16,25,35,44,53,63) as SFW1 to SFW10. The transition WT _AB 5 has, for example, (1,2,5,8,16,25,35,45,54,64) as SFW1 to SFW10.

Each luminance weight of this transition WT is set to transition gradually from WTA to WTB and from WTB to WTA. For example, each luminance weight of the transition WT is set to be a value equal to or greater than the luminance weight of the WTB below the luminance weight of the WTA. In this embodiment, each luminance weight of the transition WT is, for example, from WTA to transition WT _AB 1, from transition WT _AB 1 to transition WT _AB 2, from transition WT _AB 2 to transition WT _AB 3, and transition WT _AB. It is set to not change from 3 to transition WT _AB 4, transition WT _AB 4 to transition WT _AB 5, or transition from WT _AB 5 to WTB or decrease by one. However, the present invention is not limited to this, and each luminance weight of the transition WT may be set such that it does not change or decreases by two or more.

Each luminance weight of the transition WT is set such that the sum of the luminance weights is a constant value. In the present embodiment, the sum of the luminance weights of the transition WTs is set to 255, for example. The sum of the luminance weights of this transition WT is set equal to, for example, the sum of each luminance weight of the WTA and the sum of the luminance weights of the WTB. Therefore, the sum of the luminance weights of the transition WTs may not only be 255, but any value may be taken according to the sum of the luminance weights of the WTs.

According to the present embodiment, since each of the transition WTs has the luminance weights SFW1 to 10 as described above, it is possible to emit light without changing the light emission pattern suddenly, as described later. ), The luminance weight can be changed step by step.

The image analyzer 112 receives an input of an image signal, analyzes the image signal, and extracts features of the image signal. In this embodiment, the characteristic of this image signal is demonstrated below that it is a property that the image to display is a moving image or a still image, for example. The image analysis unit 112 may analyze, for example, whether the image to be displayed is a moving picture or a still picture based on the difference in luminance between the frames. In addition to this, the information of whether the image is a moving picture or a still picture is included in the image signal in advance, and it may be determined whether the image displayed by the image analyzing unit 112 is a moving picture or a still picture.

The image analyzing unit 112 selects one of the luminance weight table WT suitable for displaying an image corresponding to the characteristic of the image signal from the luminance weight table group 11la stored in the table storage unit 111 (selection step). . In the present embodiment, the image analysis unit 112 selects, for example, WTA if the image to be displayed is a moving picture, and selects WTB if the image to be displayed is a still image. The image analysis unit 112 then outputs the selected WT to the table output unit 113.

In the following, the image analysis unit 112, for example, analyzes the image in the past, and as a result, it is explained that the image is a moving image and WTA is selected. By the selection, the table output unit 113 outputs the selected WTA to the light emission pattern control circuit 120 and the table holding unit 114 in use (first table output step). In use, the table holding unit 114 receives the input of the WTA, and maintains the WTA as a luminance weight table that has been selected in the past and is currently used for light emission. Therefore, the table holding unit 114 in use outputs the WTA to the table output unit 113 as the luminance weight table currently being used. However, for example, when the image analyzer 112 selects a luminance weight table other than WTA in the past, the table holding unit 114 in use uses the luminance weight table currently using the luminance weight table other than the corresponding WTA. The table is held and output to the table output unit 113.

The table output unit 113 receives the input of the WTA as the in-use luminance weight table held by the table holding unit 114 in use, and receives the input of the WT newly selected by the image analysis unit 112. When the selection of the image analysis unit 112 is WTA, the table output unit 113 outputs the WTA to the light emission pattern control circuit 120 because the table output unit 113 is the same as the WTA that is the luminance weight table currently being used. However, the table output section 113 performs the following operation when the selection of the image analysis section 112 is other than WTA, for example, WTB here.

When the table output unit 113 receives the input of the WTB, the transition WT _AB 1 to the transition WT _AB 5, which is a transition WT for gradually transitioning from the WTA to the WTB, from the transition WT included in the transition luminance weight table group 11lb. Sequentially select and read (read step) and output it (output step, transition table output step). That is, the table output unit 113 sequentially outputs the transition WT _AB 1, the transition WT _AB 2, the transition WT _AB 3, the transition WT _AB 4, and the transition WT _AB 5. Then, the table output unit 113 reads out the WTB from the luminance weight table group 11la and outputs it (second table output step). At this time, the table output unit 113 outputs each transition WT _AB or WT every one frame. In the present embodiment, the table output unit 113 outputs different transition WT _AB or WT for each frame so that the output WT can be transitioned from WTA to WTB after five frames, and then transitioned from WTA to WTB in a short period of time. Can be.

However, the present invention is not limited to this example, and the table output unit 113 may output different transition WTs or WTs for a plurality of frames. The table output unit 113 sequentially selects and outputs five transition WTs (transition WT _AB 1 to transition WT _AB 5) in this embodiment, but one or more transition WTs may be selected and output. It is also possible to sequentially select and output the transition WT _AB below the place. In addition, the number of the transition WTs is appropriately set so as to prevent a sudden change in the light emission pattern and to suppress a precursor or the like observed at the user's point of view. The number of transitions (transition time) until the next transition WT or WT is output, and the number of transition WTs to be output can be appropriately changed depending on the characteristics of the image signal, the performance of the plasma display 130, and the like.

As described above, when the table output unit 113 receives the input of the WTB, the table output unit 113 outputs the transition WT _AB 1 to the transition WT _AB 5 sequentially, but again while the transition WT _AB is sequentially output. When receiving the input of the WTA, the table output unit may sequentially output the transition WT _AB outputted up to that time, and then output the WTA once again. For example, when the table output unit 113 outputs the transition WT _AB 3 and then receives the input of the WTA from the image analysis unit 112, the table output unit 113 transitions the transition WT _AB 3 and the transition WT. After sequentially outputting _AB 2 and transition WT _AB 1, WTA may be output again.

As described above, the table output unit 113 was able to gradually transition the WT from the WTA suitable for moving pictures to the WTB suitable for still images by outputting the transition WT every frame (see Fig. 4).

In addition, although the image analysis part 112 demonstrated that WTA was selected in the past, the image analysis part 112 may select WTB in the past and may select a new WTA. In this case, the table output unit 113 sequentially outputs the transition WT _AB 5, the transition WT _AB 4, the transition WT _AB 3, the transition WT _AB 2, and the transition WT _AB 1 per frame, in contrast to the output. Print the WTA. Therefore, the table output unit 113 was able to gradually transition the WT from the WTB suitable for the still picture to the WTA suitable for the moving picture by outputting the transition WT every frame (see FIG. 4).

(4. Change in luminance observed when displaying luminance 100)

5 and 6, observation is made by the user's time when the WT is changed while displaying luminance 100 (the luminance at which the sum of the luminance weights of the issued subfields is 100) in one pixel. The change in luminance, that is, the principle in which the precursor occurs, will be described. FIG. 5 is a graph showing a change in luminance observed from the user's time when the number of gradations is changed from 128 to 256 gradations by changing the weight table when the luminance 100 is displayed. FIG. 6 is a graph showing a change in luminance observed from the user's time when the number of gradations is changed from 256 to 128 gradations by changing the weight table when the luminance 100 is displayed.

FIGS. 5 and 6 (a) and (b) show a time axis along the horizontal axis, and sequentially perform the n-2th frame, the n-1th frame, the nth frame, the n + 1th frame, and the n + 2th frame. The light is emitted. In addition, the horizontal axis shows the light emission pattern in each frame typically. The vertical axis represents the luminance value observed at the user's time.

(4-1.Change from 128 to 256 gradations)

FIG. 5A shows a change in luminance when the luminance weight of each subfield is assigned based on the WTA for displaying 128 gray levels. FIG. 5B shows a change in luminance when the nth frame is suddenly changed from WTA to WTB.

In the case of using WTA, (SF1, SF3, SF4, SF5, SF6, SF7) are emitted, and the sum of the luminance weights is 100, so that luminance 100 is emitted (n- in Fig. 5A). 2 light emission pattern). In the case of using WTB, (SF1, SF2, SF3, SF4, SF5, SF6, SF8) are emitted, and the sum of the luminance weights is 100, so that luminance 100 is emitted (the nth in FIG. 5B). See the light emission pattern on the frame). Each light emission pattern for emitting such a luminance 100 is determined by the light emission pattern control circuit 120 as described above.

As shown in Fig. 5A, when the WTA is always used from the n-2 frames to the n + 2 frames, the observed luminance is almost constant, and deterioration of image quality such as a precursor is prevented. It is possible to provide an image of luminance 100 without causing. However, as shown in Fig. 5B, in the n-th frame, when the WTA is suddenly changed from WTB, the lighting period of each subfield, that is, the light emission pattern changes abruptly. The luminance observed by the light emission pattern and the integral characteristic of the time varies greatly from the nth frame to the n + 1th frame. This change in luminance is observed as a precursor to the user's time, resulting in deterioration of image quality.

(4-2.Change from 256 to 128 gradations)

6A shows a change in luminance when the luminance weight of each subfield is distributed based on the WTB for displaying 256 gray levels. FIG. 6B shows a change in luminance when the nth frame is suddenly changed from WTB to WTA.

As shown in Fig. 6A, when the WTB is always used from the n-2 frames to the n + 2 frames, the observed luminance is almost constant, and deterioration of image quality such as a precursor is prevented. An image with luminance 100 can be provided without causing. However, as shown in Fig. 6B, in the n-th frame, when the WTB is suddenly changed from WTA, the lighting period of each subfield, that is, the light emission pattern changes rapidly. The luminance observed by the light emission pattern and the integral characteristic of the time varies greatly from the nth frame to the n + 1th frame. This change in luminance is observed as a precursor to the user's time, resulting in deterioration of image quality.

(4-3. Change in luminance according to the present embodiment)

As described above, when the WT is drastically changed while displaying a constant luminance, the luminance observed by the user's time is greatly changed, and the change in the luminance is observed as a precursor. This change in luminance occurs in all pixels displaying different gradations because the emission pattern displaying any gradation changes greatly when the WT is changed rapidly (for example, in the case of WTA to WTB). Can be. Therefore, this change in luminance occurs simultaneously over a wide range of screens, and causes the fricker.

However, according to the image display device 100 according to the present embodiment, as described above, the WT is sequentially output without sequentially changing the WT, and then the WT is exchanged. Therefore, a change in the light emission pattern may occur in a pixel displaying gray scales for emitting SFs whose SFW has changed, but ends in the pixel displaying gray scales in which the SF cannot be emitted without changing the light emitting patterns. Therefore, it is possible to reduce the probability that a change in luminance observed at the time of the user as described above occurs simultaneously over a wide range of screens, and each occurrence of the change in luminance is a frame (a frame that emits light using a transition WT). Can be dispersed in

That is, according to the image display device 100 according to the present embodiment, since the SFW of each SF is converted little by little for several frames, the probability of this luminance change occurring simultaneously over a wide range of screens can be reduced. The probability of this occurrence can be reduced.

(5. Effect by Example of Operation of Table Output Circuit)

In the above, each configuration operation | movement was demonstrated in detail as an example of operation | movement of the table output circuit 110. FIG. The luminance observed at the user's time when the image display device 100 according to the present embodiment actually emits light to display the luminance 100 has been described.

As described above, according to the image display device 100 according to the first embodiment of the present invention, an image is not changed rapidly without changing the luminance weights SFW1 to SFW10 of each subfield SF1 to SF10 used for light emission. It can be changed according to the characteristics of the signal. That is, in the present embodiment, the image display device 100 can be changed in stages, for example, from 128 gray scale display to 256 gray scale display, or from 256 gray scale display to 128 gray scale display. have.

As in the conventional image display apparatus, for example, if the luminance weight for performing gradation display in 128 steps is changed from one frame to the luminance weight for performing gradation display in 256 steps, that is, from WTA in one frame, When changing to WTB, as shown in Fig. 4, all of the luminance weights SFW1 to 10 included in each of the subfields SF1 to SF10 are simultaneously changed, and each luminance weight SFW1 to 10 is changed up to seven gradations. do. Therefore, even when expressing any gray scale, the light emission pattern (lighting cycle) is suddenly changed over the entire screen, and deterioration of the image quality such as the fricker that the luminance observed by the user's vision appears to be mature due to the integration characteristics. (See FIG. 5 and FIG. 6B).

However, according to this embodiment, as shown in Fig. 4, not all of the luminance weights SFW1 to SFW10 included in each of the subfields SF1 to SF10 are changed, and each luminance weight SFW1 to 10 is in each frame. The liver changes only up to one gradation. Therefore, since the light emission pattern does not change abruptly, it is possible to lower the probability of occurrence of a precursor or the like due to the change of the light emission pattern for each frame. Therefore, the image display device 100 was able to change the luminance weight while suppressing the deterioration of image quality such as the above-mentioned precursors (see Figs. 5 and 6 (c)). In the present embodiment, however, the luminance weights SFW1 to SFW10 change only up to one gradation between the frames, but for example, they may vary by two or more gradations. The amount of change between each frame of the luminance weight may be appropriately set so that a precursor or the like is unlikely to occur.

In addition, according to the present embodiment, the luminance weights SFW1 to SFW10 can be changed in correspondence with the characteristics of the image signal without once stopping or stopping the display of the continuous image. Therefore, according to this embodiment, image quality can be improved, displaying an image continuously.

That is, in the present embodiment, the luminance weights SFW1 to SFW10 are allocated by the luminance weight table WTA for displaying the gradation in 128 steps, for example, when the image is a moving image, so that the moving image pseudo outline Can be reduced, and also the noise of the video can be reduced. In addition, since the luminance weights SFW1 to SFW10 are allocated by the luminance weight table WTB for displaying gradation in 256 steps when the image is a still image, for example, the luminance weight SFW1 to SFW10 cannot display a still image with high resolution. Can improve image quality.

(6. Another example of the operation of the table output circuit)

Next, with reference to FIGS. 7-16, each operation of the table output circuit 110 which concerns on 1st Embodiment of this invention is demonstrated in more detail, taking another specific example. In addition, below, it demonstrates focusing on difference with an example of operation | movement of the table output circuit 110 which concerns on this embodiment mentioned above, and abbreviate | omits the description about the same operation | movement.

As described above, by using only the issuance pattern having few non-light-emitting subfields (hereinafter referred to as non-light-emitting SF) in gradation display, the reduction performance of the video pseudo contour can be improved, and further, the dither method By using a plurality of image processing methods such as the above, the position of the non-luminous SF can be dispersed to improve the performance of reducing the pseudo pseudo contour. In the following, the present embodiment will be described taking as an example a case where only a light emitting pattern having a small non-emitting SF is used for gray scale display using a predetermined image processing method.

In the present example, when the light emission pattern control circuit 120 controls the light emission pattern by using the WT or the transition WT output from the table output circuit 110, the light emission pattern control circuit 120 expresses the gray scale using only the light emission pattern with low non-emission SF. Perform image processing. Therefore, before describing another example of the operation of the table output circuit 110 in detail, first, the light emission pattern by the image processing method and the image processing method will be described.

(6-1.Example of light emission pattern by image processing method and image processing method)

FIG. 7 is a diagram illustrating an example of a light emission pattern with less non-emitting SF by WTB, and FIG. 8 is a diagram illustrating an example of a light emission pattern with less non-emitting SF by WTA.

7 and 8, the light emission pattern control circuit 120 performs image processing using only a light emission pattern in which the number of non-light emission SFs between SFs that emit light is one or less. According to this image processing method, for example, in the light emission pattern for emitting the luminance 44 in FIG. 7, five consecutive SFs of (SF1 to SF5) are emitted, but the light emission pattern for emitting the luminance 40 in FIG. In the case, only one SF2 is emitted from among five consecutive SFs of (SF1 to SF5).

By limiting the light emission pattern in this manner, the number of gray scales that can be displayed is reduced, but since the number of non-light-emitting SFs can be reduced, the occurrence of video pseudo contours can be reduced. However, the present invention is not limited to this example. For example, the light emission pattern control circuit 120 may determine the light emission pattern such that the number of non-emission SFs between the light emitting SFs is two or less. In this case, the number of gradations that can be displayed increases.

In the example of the light emission patterns shown in Figs. 7 and 8, when the WTB is used, the luminance emitted is 56 steps in total (0, 2, 4, 6, 253, 255). When WTA is used, the luminance emitted is 56 steps in total (0, 1, 2, 3, 254, 255). The luminance emitted by the example of this light emission pattern is referred to herein as basic gradation, and the number of steps of luminance emitted is referred to herein as basic gradation number. In addition, since the display is further performed by using an image processing method such as a dither method, the actual gray scale display can be performed in addition to the basic gray scale. In addition, in FIG.7 and FIG.8 and FIG.13 mentioned later, "1" of each column shows light emission of corresponding SF, and "0" shows non-light emission of corresponding SF. The numerical value at the right end represents the luminance in the corresponding light emission pattern, and the numerical value immediately below each SF represents the SFW of each SF.

Next, with reference to FIG. 9 and FIG. 10, the luminance (basic gradation) issued by an example of the light emission pattern by this image processing is demonstrated. 9 is a graph illustrating an example of luminance distribution by WTB (256 gradation). 10 is a graph showing an example of luminance distribution by WTA (128 gray scales).

As shown in FIG. 9, the density | concentration generate | occur | produced in the distribution of the luminance by WTB. For example, the luminance distribution is dense at around 128 luminance. Therefore, detailed gradation representation (high gradation display) is possible at around 128 luminance. In the low luminance (near zero luminance), detailed gray scales can be expressed similarly. However, the luminance distribution is discrete, for example, near luminance 160. For example, the interval d _B of the luminance near the luminance 160 is large, and the luminance during that time cannot be displayed in the example of the present light emission pattern. Hereinafter, the skew (dense) of this distribution of luminance is called ubiquitous.

On the other hand, as shown in FIG. 10, the distribution of the brightness | luminance by WTA is reduced compared with the distribution of the brightness | luminance by WTB. For example, the interval d _A of luminance in the vicinity of luminance 160 is smaller than the interval d _B.

Therefore, in the example of the present light emission pattern, the gray scale display at a lower luminance (dark portion) is possible than the case where light emission is performed by the WTB, when light emission is performed by the WTA. On the other hand, the light emission performed by the WTA enables higher gray scale display over a wider gray scale display than when the light emission is performed by the WTB.

In addition, as described above, the gray scale display higher than the basic gray scale number (56 gray scales) is actually performed by using an image processing method such as a dither method for the half gray scale between each luminance, but the interval (d _A , d _B, etc.) of each luminance is used. If this value is large, a sense of noise remains even if the intermediate gradation between the luminance is generated using a dither method or the like. This noise is called dither noise.

Therefore, it is necessary to prevent the occurrence of such dither noise, and to define the SFW so as to make the distribution of luminance uniform and to reduce the ubiquity of the luminance. In other words, when image processing or the like is performed to reduce the number of non-emitting SFs, it is necessary to determine an optimal (when locality can be reduced) SFW for the image processing method.

(6-2.Example of WT with luminance weight with reduced ubiquitous)

Next, with reference to FIGS. 11-14, the luminance weight table WTA 'which has the luminance weight which reduced ubiquitousness suitable for an example of the light emission pattern by the said image processing method is demonstrated. 11 is a diagram illustrating an example of a luminance weight table WTA 'having luminance weight with reduced ubiquity. Fig. 12 is a graph showing the luminance weight SFW of each subfield SF of WTA, WTB, and WTA '. FIG. 13 is a diagram illustrating an example of a light emitting pattern with few non-light emitting subfields generated by WTA ′. FIG. Fig. 14 is a graph showing an example of luminance distribution by WTA '(about 128 gradations with reduced locality).

As shown in FIG. 11, WTA 'has (2,5,10,16,22,28,34,40,46,52) as SFW1-SFW10 assigned to each SF1-SF10, for example. WTA 'is SF2 of SF1 similar to the above WTA. Therefore, WTA 'is a luminance weight table for about 128 gradations (for gradation display almost the same as WTA) with reduced ubiquity. As shown in FIG. 12, WTA 'determines SFW so that the change of SFW between adjacent SFs becomes smaller compared with WTA and WTB. WTA 'determines the luminance weight so that SFW changes on a nearly straight line in SF3 to SF10 other than SF1 and SF2 having small SFW.

As shown in Fig. 13, when WTA 'is used in one example of the light emitting pattern, the luminance emitted is 56 steps in total (0, 2, 5, 7, 253, 255). This is the same as the basic gradation number by WTA and WTB in one example of the above light emission pattern. As shown in FIG. 14, the interval d _C of the luminance near the luminance 160 is smaller than the interval d _A of the WTA. Therefore, according to the distribution of luminance by WTA ', ubiquity is reduced more than the distribution of luminance by WTA shown in FIG. 10, and luminance is distributed uniformly from luminance 0 to luminance 256. FIG. Therefore, according to the WTA 'suitable for the image processing method which produces an example of the said light emission pattern, since ubiquitous brightness can be reduced, generation | occurrence | production of the said dither noise can be reduced.

According to an example of the present light emission pattern, light emission by WTA can be performed with higher gray level display in the lower luminance (dark portion) of the luminance distribution of the image signal than when light emission is performed by WTA '. . When the luminance distribution of the image signal is not much low and the luminance from the high luminance to the low luminance is uniformly included, the one that emits light using &quot; WTA &quot; A clearer image can be displayed. Accordingly, WTA is an example of a low luminance luminance weight table corresponding to a low luminance distribution, and WTA 'is an example of an all luminance luminance table corresponding to all luminance distributions.

According to this embodiment, in order to reduce the number of non-emission SFs and to reduce the occurrence of moving image pseudo contours, predetermined image processing is performed, and when the emission pattern is changed by this image processing, the ubiquity of the luminance is reduced. The luminance weight table WTA 'is used to determine the luminance weight. Therefore, when predetermined image processing is performed, the luminance weight suitable for this image processing can be assigned to each SF, so that noise (dither noise, etc.) due to image processing can be reduced. However, the present invention is not limited to this example, and in the case of performing image processing other than the above example, it is possible to appropriately set and use a WT having determined a luminance weight suitable for this image processing.

(6-3.Operation of Table Output Circuit)

In the above, before describing another example of the operation | movement of the table output circuit 110, the image processing method and WTA 'were demonstrated in detail. Hereinafter, another example of the operation of the table output circuit 110 will be described in detail.

The luminance weight table group 11la stored in the table storage section 111 includes WTA 'in addition to WTA and WTB. Then, the transition luminance weight table group 11lb is a transition WT having a luminance weight that gradually transitions in steps over several frames from the luminance weight of the WTA to the WTA 'luminance weight in addition to the transition WT _AB 1 to the transition WT _AB 5. Includes transition WT _{AA '} 1-transition WT _AA' 6.

Transition WT _{AA '} 1 to Transition WT _AA' 6 have a luminance weight that gradually transitions from each luminance weight of WTA to each luminance weight of WTA '. As shown in FIG. 15, the transition WT _{AA '} 1 has (2,4,8,13,18,26,34,42,50,58) as SFW1-SFW10, for example. The transition WT _{AA '} 2 has (2,4,8,13,19,27,34,42,49,57) as SFW1 to SFW10, for example. The transition WT _{AA '} 3 has, for example, (2,4,9,14,20,27,34,41,48,56) as SFW1 to SFW10. The transition WT _{AA '} 4 has (2,5,9,14,20,27,34,41,48,55) as SFW1 to SFW10, for example. The transition WT _{AA '} 5 has (2,5,10,15,21,27,34,40,47,54) as SFW1 to SFW10, for example. The transition WT _{AA '} 6 has, for example, (2,5,10,15,22,28,34,40,46,53) as SFW1 to SFW10.

The transition WT _{AA '} 1 to the transition WT _AA' 6 are set similarly to the transition WT _AB 1 to the transition WT _AB 5 so as to gradually transition from the luminance weight of the SFA to the luminance weight of the SFA '. Therefore, detailed description thereof is omitted here.

The image analyzer 112 receives an input of an image signal, analyzes the image signal, and extracts features of the image signal. The characteristic of this image signal is explained below as a luminance distribution in the image which shows an image signal in addition to the property that the image displayed by the example of the said table output circuit 110 is a moving image or a still image, for example.

Here, this luminance distribution is taken as the magnitude of the dark part area in the image to display, for example. Here, the area of the dark portion refers to the ratio of the dark portion (the pixel whose luminance is less than the predetermined value) to the telephone line of the display screen, and the large dark portion means the ratio of the dark portion occupies a predetermined threshold or more. The small area of the dark portion means that the proportion of the dark portion is smaller than this threshold.

In the following description, the image analysis unit 112 analyzes an image signal, for example, a property of a moving image or a still image which is a characteristic of the image signal (hereinafter referred to as "identification information") and the area of the dark portion. The nature of the magnitude (hereinafter referred to as "dark part information") is extracted.

The image analysis unit 112 selects one WT suitable for displaying an image corresponding to the characteristics of the image signal from one of the luminance weight table groups 11la stored in the table storage unit 111 (selection step). Here, the image analysis unit 112 selects WTA if the image to be displayed is a moving image, and selects WTB if the image to be displayed is a still image. The image analyzing unit 112 selects WTA ', for example, when the moving image is dark and the area of the dark portion is small in the dark portion information. The image analysis unit 112 then outputs the selected WT to the table output unit 113. However, the selection of the WT for the characteristics of the image signal is not limited to this example, and any WT may be selected as long as the WT is suitable for the characteristics of the image signal.

In the following, the image analysis unit 112, for example, describes a case where an image is a moving picture and WTA is selected as a result of analyzing an image in the past, and a case where the WTB is selected as an image is a still picture. As in the example of the operation of the table output circuit 110, when WTA is selected in the past, the table output unit 113 outputs the WTA to the light emission pattern control circuit 120 and the table holding unit 114 in use, It is assumed that the table holding unit 114 maintains the WTA during use, and the light emission pattern control circuit 120 assigns the luminance weight determined by the WTA to each SF to perform light emission. When WTB is selected in the past, the table output unit 113 outputs the WTB to the light emission pattern control circuit 120 and the table holding unit 114 in use, and the table holding unit 114 in use maintains the WTB. It is assumed that the pattern control circuit 120 performs light emission by allocating the luminance weight determined by WTB to each SF.

The table output unit 113 receives an input of WTA or WTB as the luminance weight table in use held by the table holding unit 114 in use, and receives an input of the WT newly selected by the image analysis unit 112. The table output unit 113 performs the following operation when the new selection of the image analysis unit 112 is WTA '.

First, in the case where WTA has been selected in the past, when receiving the input of WTA ', the table output unit 113 performs a stepwise transition from WTA to WTA' from the transition WT included in the transition luminance weight table group 11lb. Transition WT _{AA '} 1 to transition WT to transition WT _AA' 6 are sequentially selected and read (reading step), and outputted (output step, transition table output step). That is, the table output unit 113 sequentially outputs the transition WT _{AA '} 1, the transition WT _AA' 2, the transition WT _{AA '} 3, the transition WT _AA' 4, the transition WT _{AA '} 5, and the transition WT _AA' 6. . Then, the table output unit 113 reads out WTA 'from the luminance weight table group 11la and outputs it (second table output step). At this time, the table output unit 113 outputs each transition WT _{AA '} or WT every one frame. The table output unit 113 in the present embodiment outputs different transitions WT _{AA '} or WT for each frame, so that after six frames, the output WT can transition from WTA to WTA', and from WTA to WTA '. It can transition in a short time.

In the case where WTB has been selected in the past, the table output unit 113, when receiving the input of WTA ', transitions WT to gradually transition from WTB to WTA' from the transition WT included in the transition luminance weight table group 11lb. Sequentially select and read (read step), and output it (output step, transition table output step). In this case, the table output unit 113 first sequentially reads and outputs the transition WT _AB 1 to the transition WT _AB 5, which are the transition WTs for the stepwise transition from the WTB to the WTA, and then selects the WTA. Read and print Then, as in the case where the WTA was selected in the past, the WT transitions from the WTA to WTA '. That is, the table output unit 113 is a transition WT _AB 1, transition WT _AB 2, transition WT _AB 3, transition WT _AB 4, transition WT _AB 5, WTA, transition WT _{AA '} 1, transition WT _AA' 2, transition WT _{AA '} 3, transition WT _AA' 4, transition WT _{AA '} 5, and transition WT _AA' 6 are sequentially output. Then, the table output unit 113 reads out WTA 'from the luminance weight table group 11la and outputs it (second table output step). Therefore, in this case, the table output unit 113 outputs different transition WTs or WTs for each frame, so that after 13 frames, the output WTs can be transitioned from WTB to WTA ', and in a short period of time from WTB to WTA'. You can.

However, the present invention is not limited to this example, and the table output unit 113 may separately select the transition WT for gradually transitioning between the WTB and WTA 'included in the transition luminance weight table group 11lb. In the above example, the WTA may be output as a transition WT. In this case, the transition luminance weight table group 11lb may separately include the transition WT having the SFW such as the WTA, or may include the WTA. The WTA can also be read from the luminance weight table group 11la.

As described above, the table output unit 113 outputs the transition WT for each frame, thereby converting the WT suitable for the characteristics of the image signal and gradually transitioning the WT between WTA, WTB, and WTA '(Fig. See 16).

(7. Effect by another example of operation of table output circuit)

In the above, each configuration operation | movement was demonstrated in detail taking the other example of the operation | movement of the table output circuit 110. FIG. As described above, according to the image display device 100 according to the first embodiment of the present invention, in addition to the effect of the example of the operation of the table output circuit 110, even when predetermined image processing is performed. It is possible to change to the optimum luminance weight, and noise by image processing methods such as dither noise can be reduced. Therefore, since predetermined image processing can be performed without causing deterioration of image quality, it is possible to improve the performance of reducing video pseudo contours such as reducing the number of non-emitting SFs.

However, the present invention is not limited to this example, but corresponds to the characteristics of the image and the characteristics of the image that may affect the image quality by a plurality of image processing methods, the optimal WT can be selected, and the optimum brightness is achieved. The characteristics of the image and the optimal WT may be appropriately set so that light can be emitted using the weight.

In addition, since WTA and WTA 'can be converted according to the area of the dark part, when the area of the dark part is large in a moving picture, the gray scale display of the dark part can be made clear by emitting light by the WTA, and the area of the dark part is small. In this case, light emission by WTA 'enables clear gradation display over the entire gradations.

As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It is apparent to those skilled in the art that various modifications or modifications can be devised within the scope of the claims, and of course those belonging to the technical scope of the present invention.

In the above embodiment, it is assumed that the transition WT is included in the transition luminance weight table group 11lb stored by the table storage section 111, but the present invention is not limited to this example. For example, the transition WT may be generated by the table output section 113 (generating step), and the table storage section 111 may not store the transition luminance weight table group 11lb at this time.

In this case, the table output unit 113 may generate the transition WT such that the sum of the luminance weights determined by the transition WT becomes constant. When the luminance weights SFW1 to SFW10 of the WTs selected in the past are old SFW1 to SFW10, and the luminance weights SFW1 to SFW10 of the newly selected WT are called SFW1 to SFW10, the table output unit 113 The transition WT may be generated so that each luminance weight SFW1 to SFW10 of each transition WT fills the formula (formerly SFWn ≦ SFWn of transition WT ≤ new SFWn) or (new SFWn ≦ SFWn ≦ old SFWn). . Where n is an integer from 1 to 10. In addition, the table output unit 113 may generate the transition WT such that the difference between the SFWs of the SFs is such that the size of the precursor does not occur.

In addition, the table output unit 113 may generate the transition WT so that the light emission pattern is not changed by changing the luminance weight based on the characteristics of the image in the image analysis unit 112. For example, the image analyzing unit 112 analyzes the image signal, analyzes the luminance of each pixel of the full screen, calculates SF which does not emit light by the luminance, and the pixels having the SF which do not emit relatively Many SFs that do not emit light may be output to the table output unit 113. In addition, the table output unit 113 may generate the transition WT by changing the SFW of the SF which does not emit light. By generating the transition WT in this manner, the number of pixels whose emission pattern is changed by the change of the SFW can be reduced, and generation of the precursor and the like can be suppressed as much as possible.

Moreover, in the example of the operation | movement of the table output circuit 110 of the said embodiment, although the characteristic of the image signal was a property of whether the image to display is a moving picture or a still image, this invention is not limited to this example. The characteristic of the image signal may be, for example, the luminance distribution in the image represented by the image signal, as described in another example of the operation of the table output circuit 110. That is, the image analysis unit 112 may select, for example, a luminance weight table according to the luminance distribution in the image indicated by the image signal.

In this case, the image analysis unit 112 selects WTA, for example, when the number of pixels whose luminance is equal to or less than a certain threshold is greater than or equal to another threshold, and when the number of pixels is less than the other threshold, You can also choose WTB. In addition, the image analysis unit 112 obtains a histogram of the luminance of the image signal, calculates an average value of the luminance of each pixel, and selects WTA if the average value is equal to or less than a predetermined threshold value, and the average value is a constant threshold value. If it is above the value, WTB may be selected. The image analysis unit 112 may select the luminance weight table according to the luminance distribution in the image represented by the image signal by any other method.

In the case where there are many dark portions by selecting as described above, since WTB is selected, fine gradation can be expressed for each gradation and image quality can be improved. When the dark portion is small, since WTA is selected, the image quality when displaying moving images as described above can be improved.

As described above, according to the present invention, the luminance weight of each subfield can be changed during image display while suppressing the deterioration of the image quality such as the fricker.

Claims (18)

An image display apparatus comprising a plurality of subfields having different luminance weights indicating the number of emission or the amount of light emission allocated to a subfield, and performing multi-gradation display by controlling each of the subfields to emit or not emit light. A table storage unit for storing a plurality of luminance weight tables in which the luminance weights assigned to each subfield are determined; An image analyzer which analyzes the image signal and selects one luminance weight table corresponding to a feature of the image signal from the plurality of luminance weight tables; A table output unit which reads the luminance weight table selected by the image analysis unit from the table storage unit and outputs the read luminance weight table, The table output unit newly selects the luminance weight table from the luminance weight of the luminance weight table in which the luminance weight allocated to each subfield is selected in the past when the selection of the luminance weight table by the image analyzer is completely converted. And output one or more transition luminance weight tables that are determined to transition in stages by the luminance weight of the &lt; RTI ID = 0.0 &gt; The method of claim 1, And the table output unit sequentially outputs the plurality of transition luminance weight tables for each predetermined number of frames. The method according to claim 1 or 2, The plurality of luminance weight tables include a low gradation display luminance weight table corresponding to the low gradation display of the image signal, and a high gradation display luminance weight table corresponding to the high gradation display of the image signal. Image display device. The method of claim 3, The image analysis unit selects the low gradation display luminance weight table when the image signal represents a moving picture, and selects the high gradation display luminance weight table when the image signal represents a still image. Image display device. The method of claim 3, And the image analyzing unit selects the low gradation display luminance weight table or the high gradation display luminance weight table according to the luminance distribution indicated by the image signal. The method according to claim 1 or 2, And the plurality of luminance weight tables comprise a low luminance luminance weight table corresponding to the low luminance distribution of the image signal, and a luminance luminance table for the full luminance corresponding to the luminance distribution of the image signal. The method of claim 6, And the image analyzing unit selects the low luminance luminance weight table or the full luminance luminance weight table according to the luminance distribution indicated by the image signal. The method according to claim 1 or 2, The transition luminance weight table is stored in advance in the table storage unit, And the table output unit reads the transition luminance weight table from the table storage unit, and outputs the read transition luminance weight table. The method according to claim 1 or 2, And the table output unit generates the transition luminance weight table based on the luminance weight of the luminance weight table before and after the conversion, and outputs the generated transition luminance weight table. An image display method in which one frame of an image signal is composed of a plurality of subfields having different luminance weights indicating the number of emission or the amount of light emission allocated to the subfield, and the multi-field display is performed by controlling the respective subfields to emit or not emit light. A first table that reads one luminance weight table selected from a plurality of luminance weight tables in which the luminance weights assigned to each subfield are stored in a table storage unit, and outputs the read one selected luminance weight table; Output stage; A selection step of analyzing the image signal and newly selecting one luminance weight table corresponding to a feature of the image signal from the plurality of luminance weight tables; The luminance weight allocated to each of the subfields is gradually shifted from the luminance weight of the luminance weight table output in the first table output step to the luminance weight of the luminance weight table newly selected in the selecting step. A transition table output step of outputting one or more transition luminance weight tables defined to be; And a second table outputting step of reading out one newly selected luminance weight table in the selecting step and outputting the read one newly selected luminance weight table. The method of claim 10, And wherein said transition table outputting step sequentially outputs a plurality of said transition luminance weight tables for every predetermined number of frames. The method according to claim 10 or 11, wherein The plurality of luminance weight tables include a low gradation display luminance weight table corresponding to the low gradation display of the image signal, and a high gradation display luminance weight table corresponding to the high gradation display of the image signal. Image display method. The method of claim 12, In the selecting step, when the image signal represents a moving picture, the low gradation display luminance weight table is selected, And selecting the high gradation display luminance weight table when the image signal represents a still image. The method of claim 12, And the low gradation display luminance weight table or the high gradation display luminance weight table is selected in accordance with the luminance distribution indicated by the image signal. The method according to claim 10 or 11, wherein And the plurality of luminance weight tables comprise a low luminance luminance weight table corresponding to the low luminance distribution of the image signal and a luminance luminance table for the full luminance corresponding to the luminance distribution of the image signal. The method of claim 15, And the low brightness luminance weight table or the full brightness luminance weight table is selected in accordance with the luminance distribution indicated by the image signal. The method according to claim 10 or 11, wherein The transition table output step, A reading step of reading one or more of said transition luminance weight tables previously stored in said table storage section; And an output step of outputting the read-out one or two or more transition luminance weight tables read out in advance. The method according to claim 10 or 11, wherein The transition table output step, Generating the transition luminance weight table based on the luminance weight of the luminance weight table output in the first table output step and the luminance weight of the luminance weight table newly selected in the selecting step; And an output step of outputting the generated luminance weight table.

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