JP2010014909A - Image conversion device, image conversion method, liquid crystal display device, image conversion program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image conversion device capable of quickly converting an input image to an image without color deviation which can be discriminated when obliquely viewing the input image. <P>SOLUTION: The liquid crystal display device (image conversion device) 1 includes: an interface circuit 2 which selects a look-up table to be used by using characteristics of the whole of an image with respect to respective units constituting the image exhibited by an image signal inputted from an external part, at least one of characteristics of pixels adjoining to the unit and a luminance value of the unit and converts an image signal inputted by using the selected look-up table into an image signal exhibiting a bright image and an image signal exhibiting a dark image; and a liquid crystal driving circuit 3 for synthesizing the bright image and the dark image based on the image signal obtained by conversion and displaying the image on a liquid crystal panel 4; whereby display contents can be discriminated when obliquely viewing the input image and can be quickly converted to the image without color deviation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an image conversion device, an image conversion method, a liquid crystal display device, an image conversion program, and a recording medium that convert an image at high speed so that almost no color shift occurs when viewed obliquely.

  In a liquid crystal panel, in particular, a VA (vertical alignment) type liquid crystal panel, a phenomenon occurs in which an appearance impression is different between an image when viewed from the front and an image when viewed from an oblique direction. This phenomenon is generally called a whitish phenomenon because an image looks pale and whitish when viewed obliquely in a VA liquid crystal panel.

  In particular, in the VA (vertical alignment) type liquid crystal panel, the white-brown phenomenon is shifted between the gradation-luminance characteristics of the image when viewed from the front and the gradation-luminance characteristics of the image when viewed from the oblique side. This is a phenomenon that occurs. Here, the difference between the gradation-luminance characteristics is, specifically, as shown in FIG. 12, the image when viewed from the front increases in luminance as the gradation value increases, but when viewed from an oblique direction. In the image of (2), even if the gradation value increases in a certain gradation range, the luminance does not increase or conversely the luminance decreases (gradation inversion).

  FIG. 13 is a diagram illustrating an image (a) when an image in which a white-brown phenomenon occurs is viewed from the front, and an image (b) when viewed from an oblique direction. This image is composed of an image region 31 with a drive voltage of 1V, an image region 32 with a drive voltage of 3V, and an image region 33 with a drive voltage of 5V.

  When this image is viewed from the front, since the luminance increases as the gradation value increases, the image is displayed brighter as the gradation value increases as shown in FIG. 13A. Since inversion occurs, the image area 32 in FIG. 13B looks bright even though the gradation is smaller than that of the image area 33.

  An image processing method that solves this white-brown phenomenon is disclosed in Patent Document 1.

  Specifically, in one embodiment of the image processing method disclosed in Patent Document 1, a lookup table (LUT) is used for the input gradation of each pixel of the original image to correspond to the input gradation. Create two output gradations, light and dark, and replace each pixel in the original image with multiple pixels that combine the created pixels with a bright output gradation and pixels with a dark output gradation (space division), or the original image An image frame in which each pixel is replaced with a pixel with a light output gradation and an image frame in which each pixel of the original image is replaced with a pixel with a dark output gradation are displayed alternately (time division), space division, and time division Are combined.

  FIG. 14 shows the gradation-luminance characteristics when an image obtained by using the image processing method is viewed at an angle of 60 degrees. The curve indicated by the dotted line is the gradation-luminance characteristic of the image obtained using the image processing method, and the other curve is the gradation-luminance characteristic of the image obtained without using the image processing method. Show. FIG. 15 shows an image (a) obtained by converting the image in which the white-brown phenomenon in FIG. 13 occurs using the above-described image processing method, and the image obtained by the conversion viewed from the front, and is obtained by the conversion. It is a figure which shows the image (b) at the time of seeing the image which looked from the diagonal. This image is composed of an image area 41 having a driving voltage of 1V, an image area 42 displaying a combination of a dark area having a driving voltage of 1V and a bright area having a driving voltage of 5V, and an image area 43 having a driving voltage of 5V. Has been. When the image processing method is not performed, an image in a halftone region (near drive voltage 3V) in which whitening (gradation inversion) occurs is displayed in combination with a dark region with a drive voltage of 1V and a bright region with a drive voltage of 5V. By doing so, it can be seen that gradation inversion does not occur even when viewed obliquely.

  However, the image processing method according to the above-described embodiment has a problem in that the brightness is lowered although the browning phenomenon can be suppressed in an image viewed obliquely.

  FIG. 17 shows the gradation-luminance characteristics when an image obtained by using the image processing method is viewed at an angle of 60 degrees. The curve indicated by the dotted line is the gradation-luminance characteristic of the image obtained using the image processing method, and the other curve is the gradation-luminance characteristic of the image obtained without using the image processing method. Show. The gradation-luminance characteristics when the image obtained using the image processing method of FIG. 17 is viewed from 60 degrees obliquely are the gradation levels when the image obtained without using the image processing method is viewed from 60 degrees obliquely. It can be seen that the luminance is lowered particularly in the halftone region as compared with the tone-luminance characteristics.

  FIG. 18 shows an image composed of a low gradation area 61, a halftone area 62, and a high gradation area 63. In both FIG. 18A and FIG. 18B, the low gradation region 61 is composed of 1V pixels, and the high gradation region 63 is composed of 5V pixels. Further, the halftone area 62 in FIG. 18A is composed of 3V pixels, and the halftone area 62 in FIG. 18B is composed of a combination of 1V pixels and 5V pixels. The halftone area 62 in FIG. 18B has a lower brightness than the halftone area 62 in FIG. 18A, and the boundary line with the low gradation area 61 is difficult to see. Further, in the state where the drive voltage range of each pixel constituting the image is 1.0 V to 3.5 V, gradation inversion does not occur without using the image processing method according to the above embodiment. When the image processing method is used, only the demerit that the brightness is reduced occurs.

  An image processing method that solves the above-described problem of a decrease in luminance is disclosed in another embodiment of Patent Document 1.

  As shown in FIG. 19, an example of the image processing method according to the another embodiment uses a plurality of look-up tables and changes the look-up table to be applied for each RGB of each pixel, thereby The decline is suppressed. Specifically, a look-up table in which the luminance difference between two light and dark output pixels is reduced for the highest luminance among the RGB of each pixel, and a look in which the luminance difference is increased for the lowest luminance. An up-table is used, and a look-up table with a moderate brightness difference is used for those whose brightness is neither maximum nor minimum.

  As described above, by using different look-up tables according to the RGB luminance difference, it is possible to suppress the phenomenon that the luminance is lowered while suppressing the white-brown phenomenon.

  However, in the above conventional configuration, although the difference between the brightness of the image when viewed from the front and the brightness of the image when viewed from the diagonal can be reduced, in principle, in the image viewed from the diagonal, Since the color difference opens, there arises a problem that a color shift occurs depending on an image.

  FIG. 20B is an image when the image obtained by using the image processing method according to another embodiment is viewed from an oblique direction, and FIG. 20C is an image when viewed from the front. is there. FIG. 20A shows an input image.

  As shown in FIG. 20A, when the luminance of RGB constituting the pixel is B> G> R in many pixels constituting the input image, the image processing method according to another embodiment is used. When viewed from an oblique direction, B is brighter and R is darker when viewed from an oblique direction, so that the color is generally light blue.

  An image processing method for solving the above-described problem of color misregistration is disclosed in another example according to the above-described another embodiment of Patent Document 1.

In another example of the image processing method according to the another embodiment, processing is performed according to the luminance of a specific pixel with respect to a luminance distribution within a predetermined range, and the luminance of a certain pixel and n adjacent to the pixel are processed. It is disclosed that the luminance difference is changed in relation to the luminance with the other pixel. In this embodiment, the image processing method can solve the problem of color misregistration when viewed from an oblique direction.
JP 2004-302270 A (released on October 28, 2004)

  However, in the above-described conventional configuration, processing is performed based on the luminance of a specific pixel with respect to a luminance distribution within a predetermined range, and the luminance difference is determined by the relationship between the luminance of a certain pixel and the luminance of n pixels adjacent to the pixel. Although the problem of color misregistration is solved by changing, there arises a problem that it takes a long time to process by referring to the luminance of adjacent 1 to n pixels one by one.

  The present invention has been made in view of the above-described problems, and the object thereof is the characteristics of pixels adjacent to the unit (or the entire image) (such as the maximum value, minimum value, and average value of luminance). An image conversion apparatus, an image conversion method, an image conversion program, and a recording medium for converting an image so as not to cause color misregistration simply and efficiently by calculating using these values It is to be realized. Another object of the present invention is to realize a liquid crystal display device including such an image conversion device.

In order to solve the above problems, an image conversion apparatus according to the present invention provides:
An image conversion device for converting an input image into an output image,
Unit characteristic value calculating means for calculating a characteristic value related to a unit representing each of a plurality of areas obtained by dividing the area of the input image as a unit characteristic value;
Image area characteristic value calculating means for calculating a characteristic value relating to the image area as an image area characteristic value from a predetermined image area including at least a plurality of pixels adjacent to the unit;
Using the dark lookup table corresponding to the combination of the unit characteristic value and the image area characteristic value among a plurality of different dark lookup tables in which the dark luminance value is associated with each input luminance value, the input image is Dark image generation means for generating a dark image by converting the luminance value of each pixel constituting the image into the dark luminance value corresponding to the luminance value;
Of each of the plurality of different bright look-up tables in which a bright brightness value equal to or higher than the dark brightness value corresponding to the input brightness value is associated with each input brightness value, the unit characteristic value and the image area characteristic value Bright image generation means for generating a bright image by converting the luminance value of each pixel constituting the input image into the bright luminance value corresponding to the luminance value using a bright lookup table corresponding to the combination When,
Image generating means for generating the output image by mixing the bright image and the dark image for each unit is provided.

  According to the above configuration, the image conversion apparatus calculates the characteristic value related to the unit as the unit characteristic value. For example, the image conversion apparatus calculates the average value of the luminance of each pixel included in the unit as the unit characteristic value. Further, the image conversion apparatus calculates a characteristic value related to the image area from the predetermined image area as an image area characteristic value. For example, the image processing apparatus calculates the average value, the minimum value, and the maximum value of the luminance of the plurality of pixels as the image region characteristic value from the region including the plurality of pixels adjacent to the unit. Further, the image region characteristic value may be only the average value of the luminances of a plurality of pixels.

  Further, the image conversion device generates a bright image using a bright lookup table corresponding to the unit characteristic value and the image area characteristic value, and uses a dark lookup table corresponding to the unit characteristic value and the image area characteristic value. Since a dark image is generated and an output image can be generated by mixing a bright image and a dark image, the characteristic value can be calculated without referring to the luminance value of each surrounding pixel for each pixel and calculating. By using this, it is possible to convert an image so that no color misregistration occurs. In other words, the image conversion apparatus has an effect that the image can be converted simply and efficiently so that no color misregistration occurs.

In order to solve the above problems, an image conversion method according to the present invention provides:
An image conversion method for converting an input image into an output image,
A unit characteristic value calculating step for calculating a characteristic value relating to a unit representing each of the plurality of areas obtained by dividing the area of the input image as a unit characteristic value;
An image area characteristic value calculating step of calculating a characteristic value related to the image area as an image area characteristic value from a predetermined image area including at least a plurality of pixels adjacent to the unit;
Using the dark lookup table corresponding to the combination of the unit characteristic value and the image area characteristic value among a plurality of different dark lookup tables in which the dark luminance value is associated with each input luminance value, the input image is A dark image generating step of generating a dark image by converting the brightness value of each pixel constituting the dark brightness value corresponding to the brightness value;
Of each of the plurality of different bright look-up tables in which a bright brightness value equal to or higher than the dark brightness value corresponding to the input brightness value is associated with each input brightness value, the unit characteristic value and the image area characteristic value Bright image generation step of generating a bright image by converting the luminance value of each pixel constituting the input image into the bright luminance value corresponding to the luminance value using a bright lookup table corresponding to the combination When,
An image generation step of generating the output image by mixing the bright image and the dark image for each unit.

  According to said structure, there exists an effect similar to the image converter which concerns on this invention.

An image conversion apparatus according to the present invention includes:
The predetermined image area is preferably the entire area of the input image.

  According to said structure, there exists an effect that the said image area characteristic value can be calculated further at high speed.

An image conversion apparatus according to the present invention includes:
The predetermined image area is preferably an area composed of a plurality of pixels adjacent to the unit.

An image conversion apparatus according to the present invention includes:
It is desirable that the image area characteristic value includes an average value of luminance of pixels included in the image area.

An image conversion apparatus according to the present invention includes:
It is desirable that the image area characteristic value includes an average value of the maximum value and the minimum value of the luminance of the pixels included in the image area.

An image conversion apparatus according to the present invention includes:
It is desirable that the image area characteristic value includes a mode value of luminance of pixels included in the image area.

An image conversion apparatus according to the present invention includes:
The dark image generating means is
The smaller the value obtained by subtracting the average value of the luminance of the pixels included in the image area from the average value of the luminance of the pixels included in the unit, the smaller the value corresponding to the average value of the luminance of the pixels included in the unit. Generating a dark image using the dark lookup table having a small dark luminance value;
The bright image generating means is
The smaller the value obtained by subtracting the average value of the luminance of the pixels included in the image area from the average value of the luminance of the pixels included in the unit, the smaller the value corresponding to the average value of the luminance of the pixels included in the unit. It is desirable to generate a bright image using the bright lookup table having a large bright luminance value.

  According to said structure, there exists an effect that a color shift can be improved more.

  A liquid crystal display device according to the present invention displays an output image converted from an input image by the image conversion device.

  The liquid crystal display device preferably includes a liquid crystal layer having liquid crystal molecules having negative dielectric anisotropy and substantially vertically aligned when no voltage is applied.

  The image conversion apparatus may be realized by a computer. In this case, an image conversion program for realizing the image conversion apparatus in the computer by operating the computer as each of the above means and a computer-readable recording medium on which the image conversion program is recorded also fall within the scope of the present invention.

  As described above, the image conversion apparatus according to the present invention calculates the characteristic value related to the unit as the unit characteristic value, and calculates the predetermined characteristic value related to the image area from the predetermined image area as the image area characteristic value. . Next, the image conversion apparatus is a dark lookup table in which a dark luminance value is associated with each input luminance value, and a dark lookup table corresponding to the unit characteristic value and the image region characteristic value is used to darken the darkness value. Generate an image. Further, the image conversion apparatus is a bright lookup table in which each input luminance value is associated with a bright luminance value that is greater than or equal to the dark luminance value, and the bright look corresponding to the unit characteristic value and the image region characteristic value. A bright image is generated using an uptable. Thereafter, the generated dark image and bright image are mixed to generate an output image.

  As a result, there is an effect that the image can be converted simply and efficiently so that no color misregistration occurs.

[Embodiment 1]
An embodiment of a liquid crystal display device according to the present invention will be described with reference to FIGS. 1, 2, 5 to 8, 11, and 16.

(Configuration of the liquid crystal display device 1)
The configuration of the liquid crystal display device 1 according to the present embodiment will be described below with reference to FIG. FIG. 1 is a block diagram showing a main configuration of the liquid crystal display device 1. The liquid crystal display device 1 calculates the characteristic values (maximum luminance value, minimum luminance value, average luminance value, etc.) of the entire image based on the video signal input from the system device 10. Further, the liquid crystal display device 1 has, for each unit constituting the image, characteristic values (maximum luminance value, minimum luminance value, average luminance value, etc.) of image data adjacent to the unit, and the luminance value of the unit itself. Is calculated. The liquid crystal display device 1 selects a lookup table based on the calculated characteristic value of the entire image, the characteristic value of the image adjacent to the unit, and the luminance value of the unit, and selects two luminance values (high luminance value, And, for each unit, the pixels constituting the unit are converted into a pixel having the calculated high luminance value and a pixel having the low luminance value and displayed.

  The liquid crystal display device 1 includes an interface circuit 2, a liquid crystal driving circuit 3, a liquid crystal panel 4, a lookup table 5, a whitening correction level storage unit 6, and an image data storage unit 7.

(Operation of the liquid crystal display device 1)
The operation of the liquid crystal display device 1 according to the present embodiment will be described with reference to FIGS. 2, 5, and 6. FIG. 2 is a flowchart showing the operation of the liquid crystal display device 1 when a video signal is input from the system device 10 to the liquid crystal display device 1. 5 and 6 are flowcharts of a subroutine called from the flowchart of FIG.

  In S <b> 1, when the interface circuit 2 receives the video signal input from the system apparatus 10, the interface circuit 2 performs image resolution conversion on an image obtained based on the received video signal. After converting the resolution of the image, the luminance value of each color of RGB is calculated for each unit constituting the image. Further, the image data is stored in the image data storage unit 7, and the process proceeds to S2. The unit will be described later.

  In S2, the interface circuit 2 uses the entire image data stored in the image data storage unit 7 in S1, and characteristic values (maximum luminance value, minimum luminance value, average luminance value, etc.) of the entire image data for each RGB color. And proceed to S3. Here, these characteristic values are used for white-browning correction for emphasizing light and dark. In S3, the interface circuit 2 calculates the above-average threshold value and the below-average threshold value for each RGB color using the characteristic value calculated in S2 and a predetermined brightness enhancement margin value.

  In S4, the interface circuit 2 selects one unit that has not yet calculated the brightness / darkness-enhanced white-brown correction level and the outline-enhanced white-brown correction level from among a plurality of units constituting the image. Proceed to the emphasis whitening correction level calculation processing subroutine. S5 corresponds to S31 to S33 in FIG.

  In S31, the interface circuit 2 determines the characteristic value of the entire image data calculated in S2 and the luminance of its own unit for any one of the colors for which the brightness enhancement level is not calculated in RGB. Using the value and the above-average threshold value and below-average threshold value calculated in S3, the light / dark emphasis whitening correction level is calculated, and the process proceeds to S32. In S32, the interface circuit 2 stores the value of the light / dark emphasis whitening correction level calculated in S31 in the whitening correction level storage unit 6, and proceeds to S33.

  In S <b> 33, the interface circuit 2 determines whether or not the light / dark emphasis whitening correction level has been calculated for all RGB. When the light and dark emphasis whitening correction level is calculated for all RGB (YES in S33), the process proceeds to the contour emphasis whitening correction level calculation processing subroutine of S6. Here, S6 corresponds to S41 to S45 in FIG. If at least one of R, G, and B has not calculated a brightness / darkness enhancement whitening correction level (NO in S33), the process returns to S31.

  In S41, the interface circuit 2 uses the image adjacent to the self unit among the image data stored in the image data storage unit 7, and uses the image data adjacent to the self unit for each color of RGB (the maximum luminance value). , Minimum luminance value and average luminance value), and the process proceeds to S42. Here, these characteristic values are used for the correction of browning for contour enhancement. In S <b> 42, the interface circuit 2 calculates the above-average threshold value and the below-average threshold value for each color of RGB using the characteristic value calculated in S <b> 41 and the predetermined edge enhancement margin value.

  In S43, the interface circuit 2 determines the characteristic value of the image adjacent to the own unit calculated in S41 and the self-calculation value for any one of the colors for which the contour enhancement whitening correction level is not calculated in RGB. Using the luminance value of the unit and the above-average threshold value and the below-average threshold value calculated in S42, the contour emphasis whitening correction level is calculated, and the process proceeds to S44. In S44, the interface circuit 2 adds the value of the light / dark emphasis whitening correction level calculated in S43 to the value of the whitening correction level storage unit 6, and proceeds to S45.

  In S45, the interface circuit 2 determines whether or not the contour emphasis whitening correction level has been calculated for all RGB. When the contour emphasis whitening correction level is calculated for all RGB (YES in S45), the process proceeds to S7. If the contour emphasis whitening correction level is not calculated for at least one of RGB (NO in S45), the process returns to S43.

  In S <b> 7, the interface circuit 2 selects a predetermined look-up table (LUT) from the look-up table 5 according to the value in the white-brown correction level storage unit for each of the RGB colors. Further, the interface circuit 2 calculates the brightness value in the bright state and the brightness value in the dark state that constitutes its own unit using the selected lookup table for each of the RGB colors, and proceeds to S8.

  If there is a unit that has not calculated the brightness value in the bright state and the brightness value in the dark state (YES in S8), the process returns to S4. If no unit exists (NO in S8), the process proceeds to S9.

  In S <b> 9, the interface circuit 2 outputs the brightness value in the bright state and the brightness value in the dark state calculated in S <b> 7 to the liquid crystal drive circuit 3. The liquid crystal driving circuit 3 uses the brightness value in the bright state and the brightness value in the dark state of each unit as input, and for each unit, the brightness value of a part of the pixels constituting the unit is the brightness value in the bright state. The drive voltage is applied to each pixel of the liquid crystal panel 4 so that the luminance values of the remaining pixels constituting the unit become the luminance values in the dark state. As a result, the entire image is displayed on the liquid crystal panel 4.

(unit)
The units constituting the image will be described with reference to FIG.

  A unit means a pixel group in which a plurality of pixels are combined, or a pixel group composed of a plurality of frames, each frame including one or more pixels (groups).

  Some of the pixels that make up the unit are pixels with a certain luminance value, the remaining pixels are pixels with another luminance value, and pixels with two different luminance values are alternately arranged or displayed alternately. By doing so, the unit becomes halftone when viewed from the human eye.

  For example, as shown in FIG. 16A, when the unit is composed of a pixel 51 having a certain luminance value and a pixel 52 having another luminance value, the region of the pixel 51 is the region of the pixel 52, And it is divided into a plurality of regions by the boundary of the unit. Similarly, the region of the pixel 52 is divided into a plurality of regions by the region of the pixel 51 and the boundary of the unit. Here, as the number of the pixels 51 is equal to the number of the pixels 52 and the number of the regions of the pixel 51 and the number of the regions of the pixel 52 are larger, the gradation of the unit is larger as viewed from the human eyes. It looks like a halftone.

  Also, as shown in FIG. 16B, the unit is composed of a pixel 51 having a certain luminance value and 52 having another luminance value, and when the frame is switched, the pixel in the area where the pixel 51 was displayed. Is the luminance value of the pixel in the area where the pixel 52 is displayed, and the luminance value of the pixel in the area where the pixel 52 is displayed is the luminance value of the pixel in the area where the pixel 51 is displayed. Shall. In this case, since the frames are switched at a high speed, the gradation of the unit appears to be halftone as seen from the human eye.

  16A and 16B are given as specific examples of the unit, but the unit is not limited to these, and how many pixels are included in one frame. Also good. Further, when the unit is composed of a plurality of frames, the number of frames may be any number. Furthermore, the number of pixels having a certain luminance value and the number of pixels having different luminance values that constitute the unit may not be equal.

(Example)
An example of the present embodiment will be described with reference to FIGS. 2, 7, 8, and 11.

  First, parameters used in this embodiment will be described.

  Table 1 shows the parameters assigned to the three sets (light / dark set) of LUTs shown in FIG.

  In this way, by assigning parameters to the three sets of LUTs, the value of the whitening correction level can be used as it is for gradation conversion (S7 in FIG. 2).

  Next, Table 2 shows the types of parameters used in this embodiment and the possible values of each parameter.

  Note that the types of these parameters, the range of values that each parameter can take, and the look-up table (LUT) are just reference examples set in the present embodiment, and the liquid crystal display device according to the present embodiment. However, the present invention is not limited to this.

  Next, the operation of the liquid crystal display device 1 in the present embodiment will be specifically described. The image represented by the input video signal is the image shown in FIG.

  First, the interface circuit 2 of the liquid crystal display device 1 performs image resolution conversion. The resolution conversion performed here is a step of converting the resolution of the input image into a resolution corresponding to the number of units to be output.

  In this embodiment, the resolution of the input image is 480 pixels × 320 pixels, the configuration of one unit is 2 pixels × 2 pixels, the output resolution is 480 units × 320 units, and the liquid crystal display device has a resolution of 960 pixels × 640 pixels. This will be described in the case of outputting to.

  FIG. 8 shows image resolution conversion (from 1 pixel in FIG. 8A to 2 × 2 in FIG. 8B) performed in the liquid crystal display device according to the present embodiment when focusing on one pixel of the input image. (Conversion to pixels) and the resolution-converted image is converted into an image having a light gradation and a dark gradation (conversion from the image in FIG. 8B to the image in FIG. 8C) and output. It shows that Note that each pixel of the liquid crystal display device according to the present embodiment is made up of three sub-pixels of RGB, and after applying the resolution conversion of the present embodiment, one unit is composed of 2 × 2 pixels. It is displayed as a unit consisting of two subpixels. Of the four subpixels of each color, two subpixels (21a, 22a, 23a) are displayed with high luminance, and the remaining two subpixels (21b, 22b, 23b) are displayed with low luminance.

  As shown in FIG. 8, in the liquid crystal display device according to the present embodiment, each pixel in FIG. 8A constituting the image represented by the input video signal has two vertical and horizontal pixels as shown in FIG. 8B. Doubled (unit). Next, the obtained image data is stored in the image data storage unit 7. Further, the predetermined contrast enhancement margin value and the contour enhancement margin value are stored in the image data storage unit 7 in advance. In this embodiment, it is assumed that the contrast enhancement margin value = 0.3 and the contour enhancement margin value = 0.1.

  In this embodiment, it is shown that a bright image and a dark image are created and combined from the input unit of FIG. 8B to become the output unit of FIG. 8C. In this case, since the input resolution and the unit output resolution are equal, the gradation value of the original image is equal to the gradation value of the own unit, and the calculation of each unit gradation in S1 of FIG. 2 can be omitted. .

  Next, in S2, the interface circuit 2 calculates the maximum luminance gradation, the minimum luminance gradation, and the average luminance gradation in the entire image data. In this embodiment, R maximum luminance gradation / R minimum luminance gradation / R average luminance gradation = 200/0/100. The calculation is performed for each color of RGB, but for simplicity, only a value relating to one R color is shown as a specific example.

  In S3, the interface circuit 2 calculates the above-average threshold and the below-average threshold for each of the RGB colors as shown in the following formula. Here, a specific example is shown only for one R color.

R average or higher threshold = (R maximum luminance gradation−R average luminance gradation) * light and dark emphasis margin + R average luminance gradation R below average threshold = R average luminance gradation− (R maximum luminance) Gradation-R average luminance gradation) * margin for light and dark emphasis, that is, threshold above average of R = (200-100) * 0.3 + 100 = 130, threshold below average of R = 100- (200-100) * 0 .3 = 70.

In S4, the interface circuit 2 selects a unit to be processed, and in S5, calculates a light / dark emphasis whitening correction level for each color of RGB for the selected unit. The white-brown correction level is expressed by the following equation. Here, a specific example is shown only for one R color.
When the luminance gradation of R's own unit> the average luminance gradation of R,
R white-brown correction level = (R own unit luminance gradation-R average luminance gradation) / (R average or higher threshold-R average luminance gradation)
When the luminance gradation of the local unit of R <the average luminance gradation of R,
R white-brown correction level = (R own unit luminance gradation-R average luminance gradation) / | (R average or less threshold-R average luminance gradation) |
When the luminance gradation of the local unit of R = the average luminance gradation of R,
R white brown correction level = 0
In other words, when the selected unit has the luminance gradation of its own unit of R = 140, the R white-brown correction level = (140-100) / (130-100) = 1.33.

  Note that the value of the white-brown correction level is not obtained by linear interpolation as described above, but the luminance gradation value of the R unit itself may be weighted or not complemented.

  Next, in S6, the interface circuit 2 calculates the outline emphasis whitening correction level for each color of RGB for the selected unit. S6 corresponds to S41 to S45 in FIG.

  First, in S41, the interface circuit 2 calculates a maximum luminance gradation, a minimum luminance gradation, and an average luminance gradation in an image adjacent to the unit. In the processing unit, it is assumed that R maximum luminance gradation / R minimum luminance gradation / R average luminance gradation = 200/100/150. The calculation is performed for each color of RGB, but for simplicity, only a value relating to one R color is shown as a specific example.

  Next, in S <b> 42, the interface circuit 2 calculates the above-average threshold value and the below-average threshold value for each color of RGB as shown in the following equation. Here, a specific example is shown only for one R color.

R average or higher threshold = (R maximum luminance gradation−R average luminance gradation) * contour emphasis margin value + R average luminance gradation R below average threshold = R average luminance gradation− (R maximum) (Luminance gradation-R average luminance gradation) * Outline emphasis margin value, that is, R average or higher threshold = (200−150) * 0.1 + 150 = 155, R lower than average threshold = 150− (200−150) * 0.1 = 145.

In S43, the interface circuit 2 calculates the outline emphasis whitening correction level for each color of RGB with respect to its own unit. The white-brown correction level is expressed by the following equation. Here, a specific example is shown only for one R color.
When the luminance gradation of R's own unit> the average luminance gradation of R,
R white-brown correction level = R white-brown correction level + (R's own unit luminance gradation—R average luminance gradation) / (R average or higher threshold−R average luminance gradation)
When the luminance gradation of the local unit of R <the average luminance gradation of R,
R white-brown correction level = R white-brown correction level + (R luminance gradation of own unit−R average luminance gradation) / | (R average or lower threshold−R average luminance gradation) |
When the luminance gradation of the local unit of R = the average luminance gradation of R,
R white-brown correction level = R white-brown correction level, that is, when the selected unit has a luminance gradation of its own unit = 140, R white-brown correction level = 1.33 + (140−150) / | (145-150) | = −0.67.

  As described above, the brightness correction level value is not obtained by linear interpolation, but the luminance gradation value of the own unit may be weighted or not complemented.

In S <b> 7, the interface circuit 2 performs tone conversion using the selected look-up table (LUT) based on the obtained white-brown correction level value. In this example,
White brown correction level <=-1: -1 LUT is used -1 <White brown correction level <0: -1 and 0 LUT are used by linear interpolation White brown correction level = 0: 0 LUT 0 <white-brown correction level <1: 0 and 1 LUT are used by linear interpolation 1 <= white-brown correction level: 1 LUT is selected according to use of LUT. Here, since the R browning correction level = −0.67, 0 LUT and −1 LUT are used, but when the luminance gradation of the R unit itself is 140, as shown in FIG. The bright and dark luminances of the 0 LUT are 181 and 70, respectively, and the bright and dark luminances of the -1 LUT are 190 and 24, respectively. When complemented directly, the bright luminance is 187 and the dark luminance is 39.

  In S7, the bright luminance and the dark luminance are calculated by linear interpolation. However, instead of linear interpolation, weighting may be performed, or interpolation may not be performed.

  Next, in S8, if there is a unit for which the bright luminance and the dark luminance are not calculated, the next unit is processed. If not, finally, in S9, the interface circuit 2 determines each unit calculated in S7. The brightness value in the bright state and the brightness value in the dark state are output to the liquid crystal drive circuit 3. The liquid crystal driving circuit 3 uses the brightness value in the bright state and the brightness value in the dark state of each unit as input, and for each unit, the brightness value of a part of the pixels constituting the unit is the brightness value in the bright state. The drive voltage is applied to each pixel of the liquid crystal panel 4 so that the luminance values of the remaining pixels constituting the unit become the luminance values in the dark state. As a result, the entire image is displayed on the liquid crystal panel 4.

(Application result)
FIG. 11B is an image when the image obtained by converting the right half of the image of FIG. 11A using the above algorithm is viewed obliquely. FIG. 11C shows an image obtained by converting the right half of the image of FIG. 11A using the above algorithm and converting the left half using a conventional method from the front. It is an image when seen. As can be confirmed by comparing the left and right halves converted using the conventional method, by combining light and dark emphasis and contour emphasis, even with the same color (gradation), white-brown By changing the level, it is possible to display an easy-to-see image with little whitening even when viewed obliquely.

[Embodiment 2]
Another embodiment of the liquid crystal display device according to the present invention will be described with reference to FIGS. 1, 3, and 5 to 9. FIG.

(Configuration of the liquid crystal display device 1)
The configuration of the liquid crystal display device 1 according to the present embodiment will be described below with reference to FIG. FIG. 1 is a block diagram showing a main configuration of the liquid crystal display device 1. The liquid crystal display device 1 calculates the characteristic values (maximum luminance value, minimum luminance value, average luminance value, etc.) of the entire image based on the video signal input from the system device 10. Further, the liquid crystal display device 1 calculates a luminance value for each unit constituting the image. The liquid crystal display device 1 calculates two luminance values (a high luminance value and a low luminance value) by selecting a lookup table to be used based on the calculated characteristic value of the entire image and the luminance value of the unit. For each unit, the pixels constituting the unit are converted into a pixel having the calculated high luminance value and a pixel having the low luminance value and displayed.

  The liquid crystal display device 1 includes an interface circuit 2, a liquid crystal driving circuit 3, a liquid crystal panel 4, a lookup table 5, a whitening correction level storage unit 6, and an image data storage unit 7.

(Operation of the liquid crystal display device 1)
The operation of the liquid crystal display device 1 according to this embodiment will be described with reference to FIGS. 3 and 5. FIG. 3 is a flowchart showing the operation of the liquid crystal display device 1 when a video signal is input from the system device 10 to the liquid crystal display device 1. FIG. 5 is a flowchart of a subroutine called from the flowchart of FIG.

  In S <b> 11, when the interface circuit 2 receives the video signal input from the system apparatus 10, the interface circuit 2 performs image resolution conversion on an image obtained based on the received video signal. After converting the resolution of the image, the luminance value of each color of RGB is calculated for each unit constituting the image. Further, the image data is stored in the image data storage unit 7, and the process proceeds to S12. The description of the unit is omitted since it is performed in the first embodiment.

  In S12, the interface circuit 2 uses the entire image data stored in the image data storage unit 7 in S11, and the characteristic values of the entire image data for each RGB color (maximum luminance value, minimum luminance value, average luminance value, etc.). And proceeds to S13. Here, these characteristic values are used for white-browning correction for emphasizing light and dark. In S13, the interface circuit 2 calculates the above-average threshold value and the below-average threshold value for each of the RGB colors using the characteristic value calculated in S12 and a predetermined light / dark enhancement margin value.

  In S14, the interface circuit 2 selects one unit that has not yet calculated the light / dark emphasis whitening correction level from among the plurality of units constituting the image, and proceeds to the light / dark emphasis whitening correction level calculation processing subroutine of S15. . S15 corresponds to S31 to S33 in FIG.

  In S31, the interface circuit 2 determines the characteristic value of the entire image data calculated in S12 and the luminance of its own unit for any one of the RGB colors for which the brightness enhancement level is not calculated. Using the value and the above-average threshold value and the below-average threshold value calculated in S13, the light / dark emphasis whitening correction level is calculated, and the process proceeds to S32. In S32, the interface circuit 2 stores the value of the light / dark emphasis whitening correction level calculated in S31 in the whitening correction level storage unit 6, and proceeds to S33.

  In S <b> 33, the interface circuit 2 determines whether or not the light / dark emphasis whitening correction level has been calculated for all RGB. If the brightness enhancement level for all RGB is calculated (YES in S33), the process proceeds to S16. If at least one of R, G, and B has not calculated a brightness / darkness enhancement whitening correction level (NO in S33), the process returns to S31.

  In S <b> 16, the interface circuit 2 selects a predetermined look-up table (LUT) from the look-up table 5 according to the value of the white-brown correction level storage unit for each of the RGB colors. Further, the interface circuit 2 calculates the luminance value in the bright state and the luminance value in the dark state that constitutes the unit using the selected lookup table for each of the RGB colors, and proceeds to S17.

  When there is a unit that has not calculated the brightness value in the bright state and the brightness value in the dark state (YES in S17), the process returns to S14. If no unit exists (NO in S17), the process proceeds to S18.

  In S <b> 18, the interface circuit 2 outputs the brightness value in the bright state and the brightness value in the dark state of each unit calculated in S <b> 16 to the liquid crystal drive circuit 3. The liquid crystal driving circuit 3 uses the brightness value in the bright state and the brightness value in the dark state of each unit as input, and for each unit, the brightness value of a part of the pixels constituting the unit is the brightness value in the bright state. The drive voltage is applied to each pixel of the liquid crystal panel 4 so that the luminance values of the remaining pixels constituting the unit become the luminance values in the dark state. As a result, the entire image is displayed on the liquid crystal panel 4.

(Example)
An example of the present embodiment will be described with reference to FIGS. 3, 7, 8, and 9. The description of the parameters used in this example is omitted because it is described in Tables 1 and 2 of the example of the first embodiment.

  The operation of the liquid crystal display device 1 in this embodiment will be specifically described. The image represented by the input video signal is the image shown in FIG.

  The interface circuit 2 of the liquid crystal display device 1 performs image resolution conversion.

  FIG. 8 shows image resolution conversion performed in the liquid crystal display device according to the present embodiment.

  As shown in FIG. 8, in the liquid crystal display device according to the present embodiment, each pixel in FIG. 8A constituting the image represented by the input video signal has two vertical and horizontal pixels as shown in FIG. 8B. Doubled (unit). Next, the obtained image data is stored in the image data storage unit 7. In addition, a predetermined contrast enhancement margin value is stored in the image data storage unit 7 in advance. In the present embodiment, it is assumed that the light and dark emphasis margin value = 0.3.

  In this embodiment, it is shown that a bright image and a dark image are created and combined from the input unit of FIG. 8B to become the output unit of FIG. 8C. In this case, since the input resolution and the unit output resolution are equal, the gradation value of the original image is equal to the gradation value of the own unit, and the calculation of each unit gradation in S11 of FIG. 3 can be omitted. .

  Next, in S12, the interface circuit 2 calculates the maximum luminance gradation, the minimum luminance gradation, and the average luminance gradation in the entire image data. In this embodiment, R maximum luminance gradation / R minimum luminance gradation / R average luminance gradation = 200/0/100. The calculation is performed for each color of RGB, but for simplicity, only a value relating to one R color is shown as a specific example.

  In S13, the interface circuit 2 calculates the above-average threshold and the below-average threshold for each of the RGB colors as shown in the following equation. Here, a specific example is shown only for one R color.

R average or higher threshold = (R maximum luminance gradation−R average luminance gradation) * margin value for contrast enhancement + R average luminance gradation R average or lower threshold = R average luminance gradation− (R maximum) (Luminance gradation-R average luminance gradation) * Margin value for light and dark emphasis, ie, R average or higher threshold = (200-100) * 0.3 + 100 = 130, R average lower threshold = 100- (200-100) * 0.3 = 70.

In S14, the interface circuit 2 selects a unit to be processed, and in S15, for the selected unit, the interface circuit 2 calculates a light / dark emphasis whitening correction level for each of the RGB colors to obtain a whitening correction level. The white-brown correction level is expressed by the following equation. Here, a specific example is shown only for one R color.
When the luminance gradation of R's own unit> the average luminance gradation of R,
R white-brown correction level = (R own unit luminance gradation-R average luminance gradation) / (R average or higher threshold-R average luminance gradation)
When the luminance gradation of the local unit of R <the average luminance gradation of R,
R white-brown correction level = (R own unit luminance gradation-R average luminance gradation) / | (R average or less threshold-R average luminance gradation) |
When the luminance gradation of the local unit of R = the average luminance gradation of R,
R white brown correction level = 0
In other words, when the selected unit has the luminance gradation of its own unit of R = 140, the R white-brown correction level = (140-100) / (130-100) = 1.33.

  As described above, the brightness correction level value is not obtained by linear interpolation, but the luminance gradation value of the own unit may be weighted or not complemented.

In S16, the interface circuit 2 performs gradation conversion using a lookup table (LUT) selected based on the obtained white-brown correction level value. In this example,
White brown correction level <=-1: -1 LUT is used -1 <White brown correction level <0: -1 and 0 LUT are used by linear interpolation White brown correction level = 0: 0 LUT 0 <white-brown correction level <1: 0 and 1 LUT are used by linear interpolation 1 <= white-brown correction level: 1 LUT is selected according to use of LUT. Here, since the white blur correction level of R = 1.33, one LUT is used. However, when the own unit has the luminance gradation of the own unit of R = 140, as shown in FIG. The bright luminance and dark luminance of the LUT are 140, respectively.

  Note that when calculating the bright luminance and the dark luminance in S16, weighting may be performed instead of linear interpolation, or interpolation may not be performed.

  Next, in S17, if there is a unit for which the bright luminance and the dark luminance are not calculated, the process returns to S14 and the next unit is processed. If not, finally in S18, the interface circuit 2 calculates in S16. The brightness value in the bright state and the brightness value in the dark state of each unit are output to the liquid crystal drive circuit 3. The liquid crystal driving circuit 3 uses the brightness value in the bright state and the brightness value in the dark state of each unit as input, and for each unit, the brightness value of a part of the pixels constituting the unit is the brightness value in the bright state. The drive voltage is applied to each pixel of the liquid crystal panel 4 so that the luminance values of the remaining pixels constituting the unit become the luminance values in the dark state. As a result, the entire image is displayed on the liquid crystal panel 4.

(Application result)
FIG. 9B shows an image obtained by converting the right half of the image of FIG. 9A using the above algorithm and converting the left half using the conventional method from an oblique direction. It is an image of the case. FIG. 9C shows an image obtained by converting the right half of the image of FIG. 9A using the above algorithm and converting the left half using a conventional method from the front. It is an image when seen. As can be seen from the right half of the image of FIG. 9 (b), the gradation data of the entire image is read, and when it is brighter than the average, the white-brown correction is minimized, and when it is darker than the average, By setting the white-brown correction to the maximum, the brightness does not decrease much even when viewed obliquely, and a sharp image can be displayed.

[Embodiment 3]
Another embodiment of the liquid crystal display device according to the present invention will be described with reference to FIGS. 1, 4, 6 to 8, and 10.

(Configuration of the liquid crystal display device 1)
The configuration of the liquid crystal display device 1 according to the present embodiment will be described below with reference to FIG. FIG. 1 is a block diagram showing a main configuration of the liquid crystal display device 1. Based on the video signal input from the system device 10, the liquid crystal display device 1 uses the characteristic values (maximum luminance value, minimum luminance value, and average luminance) of image data adjacent to the unit for each unit constituting the image. Value) and the luminance value of the unit itself. The liquid crystal display device 1 selects a look-up table to be used based on the calculated characteristic value of the image adjacent to the own unit and the luminance value of the own unit and selects two luminance values (high luminance value and For each unit, the pixels constituting the unit are converted into a pixel having the calculated high luminance value and a pixel having the low luminance value and displayed.

  The liquid crystal display device 1 includes an interface circuit 2, a liquid crystal driving circuit 3, a liquid crystal panel 4, a lookup table 5, a whitening correction level storage unit 6, and an image data storage unit 7.

(Operation of the liquid crystal display device 1)
The operation of the liquid crystal display device 1 according to the present embodiment will be described with reference to FIGS. 4 and 6. FIG. 4 is a flowchart showing the operation of the liquid crystal display device 1 when a video signal is input from the system device 10 to the liquid crystal display device 1. FIG. 6 is a flowchart of a subroutine called from the flowchart of FIG.

  In S <b> 21, when the interface circuit 2 receives the video signal input from the system apparatus 10, the interface circuit 2 performs image resolution conversion on an image obtained based on the received video signal. After converting the resolution of the image, the luminance value of each color of RGB is calculated for each unit constituting the image. Further, the image data is stored in the image data storage unit 7, and the process proceeds to S22. The description of the unit is omitted since it is performed in the first embodiment.

  In S22, the interface circuit 2 selects one unit that has not yet calculated the contour enhancement whitening correction level from the plurality of units constituting the image, and enters the contour enhancement whitening correction level calculation processing subroutine in S23. move on. S23 corresponds to S41 to S45 in FIG.

  In S <b> 41, the interface circuit 2 uses the image adjacent to the self unit among the image data stored in the image data storage unit 7, and the characteristic value (maximum luminance value, minimum (Luminance value and average luminance value) are calculated, and the process proceeds to S42. Here, these characteristic values are used for the correction of browning for contour enhancement. In S42, the interface circuit 2 calculates the above-average threshold and the below-average threshold for each color of RGB using the characteristic value calculated in S41 and a predetermined edge emphasis margin value.

  In S43, the interface circuit 2 determines the characteristic value of the image adjacent to the own unit calculated in S41 and the self-calculation value for any one of the colors for which the contour enhancement whitening correction level is not calculated in RGB. Using the luminance value of the unit and the above-average threshold value and the below-average threshold value calculated in S42, the contour emphasis whitening correction level is calculated, and the process proceeds to S44. In S44, the interface circuit 2 sets the value of the white-brown correction level storage unit 6 to 0, and then adds the value of the contrast enhancement level calculated in S43, and the process proceeds to S45.

  In S45, the interface circuit 2 determines whether or not the contour emphasis whitening correction level has been calculated for all RGB. When the contour emphasis whitening correction level is calculated for all RGB (YES in S45), the process proceeds to S24. If at least one of RGB is not calculated with the outline emphasis whitening correction level (NO in S45), the process returns to S43.

  In S <b> 24, the interface circuit 2 selects a predetermined look-up table (LUT) from the look-up table 5 according to the value of the white-brown correction level storage unit for each of the RGB colors. Further, the interface circuit 2 calculates the brightness value in the bright state and the brightness value in the dark state that constitute the unit using the selected lookup table for each of the RGB colors, and proceeds to S25.

  If there is a unit that has not calculated the brightness value in the bright state and the brightness value in the dark state (YES in S25), the process returns to S22. If no unit exists (NO in S25), the process proceeds to S26.

  In S <b> 26, the interface circuit 2 outputs the brightness value in the bright state and the brightness value in the dark state of each unit calculated in S <b> 24 to the liquid crystal drive circuit 3. The liquid crystal driving circuit 3 uses the brightness value in the bright state and the brightness value in the dark state of each unit as input, and for each unit, the brightness value of a part of the pixels constituting the unit is the brightness value in the bright state. The drive voltage is applied to each pixel of the liquid crystal panel 4 so that the luminance values of the remaining pixels constituting the unit become the luminance values in the dark state. As a result, the entire image is displayed on the liquid crystal panel 4.

(Example)
An example of this embodiment will be described with reference to FIGS. 4, 7, 8, and 10. The description of the parameters used in this example is omitted because it is described in Tables 1 and 2 of the example of the first embodiment.

  The operation of the liquid crystal display device 1 in this embodiment will be specifically described. The image represented by the input video signal is the image shown in FIG.

  First, the interface circuit 2 of the liquid crystal display device 1 performs image resolution conversion.

  FIG. 8 shows image resolution conversion performed in the liquid crystal display device according to the present embodiment.

  As shown in FIG. 8, in the liquid crystal display device according to the present embodiment, each pixel in FIG. 8A constituting the image represented by the input video signal has two vertical and horizontal pixels as shown in FIG. 8B. Doubled (unit). Next, the obtained image data is stored in the image data storage unit 7. Further, the margin emphasis margin value is stored in the image data storage unit 7 in advance. In the present embodiment, the edge enhancement margin value = 0.1.

  In this embodiment, it is shown that a bright image and a dark image are created and combined from the input unit of FIG. 8B to become the output unit of FIG. 8C. In this case, since the input resolution and the unit output resolution are equal, the gradation value of the original image is equal to the gradation value of the own unit, and the calculation of each unit gradation in S21 of FIG. 4 can be omitted. .

  Next, in S22, the interface circuit 2 selects a unit to be processed. In S23, for the selected unit, the contour emphasis whitening correction level is calculated for each color of RGB. S23 corresponds to S41 to S45 in FIG.

  First, in S41, the interface circuit 2 calculates a maximum luminance gradation, a minimum luminance gradation, and an average luminance gradation in an image adjacent to the unit. In the processing unit, it is assumed that R maximum luminance gradation / R minimum luminance gradation / R average luminance gradation = 200/100/150. The calculation is performed for each color of RGB, but for simplicity, only a value relating to one R color is shown as a specific example.

  Next, in S <b> 42, the interface circuit 2 calculates the above-average threshold value and the below-average threshold value for each color of RGB as shown in the following equation. Here, a specific example is shown only for one R color.

R average or higher threshold = (R maximum luminance gradation−R average luminance gradation) * contour emphasis margin value + R average luminance gradation R below average threshold = R average luminance gradation− (R maximum) (Luminance gradation-R average luminance gradation) * Outline emphasis margin value, that is, R average or higher threshold = (200−150) * 0.1 + 150 = 155, R lower than average threshold = 150− (200−150) * 0.1 = 145.

In S43, the interface circuit 2 calculates the outline emphasis whitening correction level for each color of RGB with respect to its own unit. The white-brown correction level is expressed by the following equation. Here, a specific example is shown only for one R color.
When the luminance gradation of R's own unit> the average luminance gradation of R,
R white-brown correction level = (R own unit luminance gradation-R average luminance gradation) / (R average or higher threshold-R average luminance gradation)
When the luminance gradation of the local unit of R <the average luminance gradation of R,
R white-brown correction level = (R own unit luminance gradation-R average luminance gradation) / | (R average or less threshold-R average luminance gradation) |
When the luminance gradation of the local unit of R = the average luminance gradation of R,
R white brown correction level = 0
That is, when the selected unit has the luminance gradation of its own unit of R = 140, the R white-brown correction level = (140−150) / | (145−150) | = −2.

  As described above, the brightness correction level value is not obtained by linear interpolation, but the luminance gradation value of the own unit may be weighted or not complemented.

In S24, tone conversion is performed using the selected look-up table (LUT) based on the obtained white-brown correction level value. In this example,
White brown correction level <=-1: -1 LUT is used -1 <White brown correction level <0: -1 and 0 LUT are used by linear interpolation White brown correction level = 0: 0 LUT 0 <white-brown correction level <1: 0 and 1 LUT are used by linear interpolation 1 <= white-brown correction level: 1 LUT is selected according to use of LUT. Here, since the white blur correction level of R = −2, the LUT of −1 is used. However, when the own unit has the luminance gradation of the own unit of R = 140, as shown in FIG. The light luminance and dark luminance of one LUT are 190 and 24, respectively.

  Note that, when calculating the bright luminance and the dark luminance in S24, weighting may be performed instead of linear interpolation, or interpolation may not be performed.

  Next, in S25, if there is a unit for which the bright luminance and the dark luminance are not calculated, the process returns to S22 and the next unit is processed. If not, finally in S26, the interface circuit 2 calculates in S24. The brightness value in the bright state and the brightness value in the dark state of each unit are output to the liquid crystal drive circuit 3. The liquid crystal driving circuit 3 uses the brightness value in the bright state and the brightness value in the dark state of each unit as input, and for each unit, the brightness value of a part of the pixels constituting the unit is the brightness value in the bright state. The drive voltage is applied to each pixel of the liquid crystal panel 4 so that the luminance values of the remaining pixels constituting the unit become the luminance values in the dark state. As a result, the entire image is displayed on the liquid crystal panel 4.

(Application result)
FIG. 10B shows the image obtained by converting the right half of the image of FIG. 10A using the above algorithm and the image obtained by converting the left half using the conventional method from an oblique direction. It is an image of the case. FIG. 10C shows an image obtained by converting the right half of the image of FIG. 10A using the above algorithm and converting the left half using a conventional method from the front. It is an image when seen. The average value of the brightness of the pixels adjacent to the own unit is compared. If the brightness of the own unit is greater than the average value of the brightness of the adjacent pixels, the whitening correction is reduced. Also, if the brightness of the own unit is smaller than the average value of the brightness of adjacent pixels, the white-brown correction is increased. Thereby, an outline is emphasized and a sharp image can be displayed.

(Advantages of the liquid crystal display device 1)
As described above, the liquid crystal display device according to each embodiment of the present invention calculates at least one of the characteristic value of the image adjacent to the unit or the characteristic value of the entire image in each unit, and based on the calculated characteristic value. Compared to converting an image by referring to the brightness of 1 to n pixels adjacent to each other one by one, there is no whitening phenomenon even when viewed obliquely, and the color shift. It is possible to convert an image with no image at high speed.

(Program, recording medium)
Each block included in the liquid crystal display device (image conversion device) 1 may be configured by hardware logic. Alternatively, it may be realized by software using a CPU (Central Processing Unit) as follows.

  In other words, the liquid crystal display device 1 only needs to record the program code (execution format program, intermediate code program, source program) of a control program that realizes each function so that it can be read by a computer. The liquid crystal display device 1 (or CPU or MPU) may read and execute the program code recorded on the supplied recording medium.

  The recording medium for supplying the program code to the liquid crystal display device 1 is, for example, a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, or a CD-ROM / MO / MD / DVD / CD. A disk system including an optical disk such as -R, a card system such as an IC card (including a memory card) / optical card, or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM.

  Further, even if the liquid crystal display device 1 is configured to be connectable to a communication network, the object of the present invention can be achieved. In this case, the program code is supplied to the liquid crystal display device 1 via a communication network. The communication network may be any network that can supply program codes to the liquid crystal display device 1 and is not limited to a specific type or form. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, mobile communication network, satellite communication network, etc. may be used.

  The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, wired communication such as IEEE 1394, USB (Universal Serial Bus), power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared light such as IrDA or remote control, Bluetooth (registered trademark), 802. 11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, etc. can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

(Additional notes)
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  Further, in each embodiment, the examples have been described by taking the case where the maximum luminance value, the minimum luminance value, and the average luminance value are used as the characteristic values, but the characteristic values are not limited to these. . For example, the characteristic value may include a median value of luminance, a mode value of luminance, or an average value of the maximum luminance value and the minimum luminance value.

  The image conversion apparatus according to the present invention can be widely used such as a large-screen liquid crystal television set that is expected to be viewed by a large number of people and is expected to be viewed from an angleless position. .

It is a block diagram which shows the principal part structure of the liquid crystal display device which concerns on Embodiment 1-3 of this invention. 3 is a flowchart showing the operation of the liquid crystal display device according to the first embodiment of the present invention. It is a flowchart showing operation | movement of the liquid crystal display device which concerns on Embodiment 2 of this invention. It is a flowchart showing operation | movement of the liquid crystal display device which concerns on Embodiment 3 of this invention. It is a flowchart of the subroutine called from Embodiment 1 and 2 of this invention. It is a flowchart of the subroutine called from Embodiment 1 and 3 of this invention. It is a figure which shows the look-up table (LUT) used in each Example of Embodiment 1-3 of this invention. It is a figure which shows converting the resolution of an image used in each Example of Embodiment 1-3 of this invention, and the input unit into the output unit comprised by a low-intensity pixel and a high-intensity pixel. The image conversion in the example of Embodiment 2 of the present invention is applied to the image obtained by combining the same landscape images side by side and the right half of the combined image, and the conventional method is applied to the left half of the combined image. It is a figure which consists of the image at the time of seeing the image obtained by applying the method of 2 from the diagonal, and the image at the time of seeing the obtained image from the front. The image conversion in the example of Embodiment 3 of the present invention is applied to the image obtained by combining the same landscape images side by side and the right half of the combined image, and the conventional image is applied to the left half of the combined image. It is a figure which consists of the image at the time of seeing the image obtained by applying the method of 2 from the diagonal, and the image at the time of seeing the obtained image from the front. The image conversion in the example of Embodiment 1 of the present invention is applied to the image obtained by combining the same landscape images side by side and the right half of the combined image, and the conventional image is applied to the left half of the combined image. It is a figure which consists of the image at the time of seeing the image obtained by applying the method of 2 from the diagonal, and the image at the time of seeing the obtained image from the front. FIG. 6 is a diagram illustrating gradation-luminance characteristics when an image is viewed from various angles when an input image is displayed as it is without performing image conversion processing in the related art. In the related art, when an input image is displayed as it is without performing image conversion processing, it is a diagram illustrating a difference between an image viewed from the front and an image viewed from an oblique direction. In the prior art, the tone-brightness characteristics when viewing an image from various angles when the input image is displayed as it is without performing image conversion processing, and the halftone area are combined with low luminance pixels and high luminance pixels It is the figure which compared the gradation-luminance characteristic at the time of seeing an image from 60 degree | times diagonally in the case of converting and displaying an image. The figure which shows the difference between the image when it sees from the front, and the image when it sees from the diagonal, when a halftone area | region is converted and displayed on the image which combined the low-intensity pixel and the high-intensity pixel in the prior art. It is. It is a figure explaining the concept of the unit used in each embodiment of the present invention. In the prior art, when the halftone area is converted into an image that combines low-brightness pixels and high-brightness pixels and displayed, the brightness that explains that the brightness of the halftone area is lower than when no image conversion processing is performed -It is a figure of a gradation characteristic. In the prior art, the halftone area is converted into an image combining low-luminance pixels and high-luminance pixels and displayed, and a diagram showing a difference between a screen when viewed obliquely and a screen when image conversion processing is not performed. is there. 12 is a flowchart showing an operation of selecting a lookup table (LUT) to be applied to each RGB sub-pixel constituting a pixel in another image processing method according to the prior art. It is the input image used in the example which applied another image processing method of a prior art, and an output image.

Explanation of symbols

1 Liquid crystal display device (image conversion device)
DESCRIPTION OF SYMBOLS 2 Interface circuit 3 Liquid crystal drive circuit 4 Liquid crystal panel 5 Look-up table 6 White-brown correction level storage part 7 Image data storage part 10 System apparatus 21 Red sub pixel 21a High luminance red sub pixel 21b Low luminance red sub pixel 22 green subpixel 22a high brightness green subpixel 22b low brightness green subpixel 23 blue subpixel 23a high brightness blue subpixel 23b low brightness blue subpixel 31 composed of pixels with drive voltage 1V Image region 32 image region composed of pixels of drive voltage 3V 33 image region composed of pixels of drive voltage 5V 41 image region composed of pixels of drive voltage 1V 42 pixel of drive voltage 1V and drive voltage 5V An image area composed of pixels of 43 An image area composed of pixels with a drive voltage of 5V Area

Claims (12)

An image conversion device for converting an input image into an output image,
Unit characteristic value calculating means for calculating a characteristic value related to a unit representing each of a plurality of areas obtained by dividing the area of the input image as a unit characteristic value;
Image area characteristic value calculating means for calculating a characteristic value relating to the image area as an image area characteristic value from a predetermined image area including at least a plurality of pixels adjacent to the unit;
Using the dark lookup table corresponding to the combination of the unit characteristic value and the image area characteristic value among a plurality of different dark lookup tables in which the dark luminance value is associated with each input luminance value, the input image is Dark image generation means for generating a dark image by converting the luminance value of each pixel constituting the image into the dark luminance value corresponding to the luminance value;
Of each of the plurality of different bright look-up tables in which a bright brightness value equal to or higher than the dark brightness value corresponding to the input brightness value is associated with each input brightness value, the unit characteristic value and the image area characteristic value Bright image generation means for generating a bright image by converting the luminance value of each pixel constituting the input image into the bright luminance value corresponding to the luminance value using a bright lookup table corresponding to the combination When,
An image conversion apparatus comprising: an image generation unit configured to generate the output image by mixing the bright image and the dark image for each unit. The predetermined image area is the entire area of the input image,
The image conversion apparatus according to claim 1. The predetermined image area is an area composed of a plurality of pixels adjacent to the unit.
The image conversion apparatus according to claim 1. The image region characteristic value includes an average value of luminance of pixels included in the image region,
The image conversion apparatus according to any one of claims 1 to 3. The image region characteristic value includes an average value of a maximum value and a minimum value of luminance of pixels included in the image region,
The image conversion apparatus according to any one of claims 1 to 3. The image area characteristic value includes a mode value of luminance of pixels included in the image area,
The image conversion apparatus according to any one of claims 1 to 3. The dark image generating means includes
The smaller the value obtained by subtracting the average value of the luminance of the pixels included in the image area from the average value of the luminance of the pixels included in the unit, the smaller the value corresponding to the average value of the luminance of the pixels included in the unit. Generating a dark image using the dark lookup table having a small dark luminance value;
The bright image generating means
The smaller the value obtained by subtracting the average value of the luminance of the pixels included in the image area from the average value of the luminance of the pixels included in the unit, the smaller the value corresponding to the average value of the luminance of the pixels included in the unit. Generating a bright image using the bright lookup table having a large bright luminance value,
The image conversion apparatus according to claim 4. An image conversion device according to any one of claims 1 to 7, comprising:
A liquid crystal display device that displays an output image converted from an input image by the image conversion device. It has a negative dielectric anisotropy and comprises a liquid crystal layer containing liquid crystal molecules that are aligned substantially vertically when no voltage is applied.
The liquid crystal display device according to claim 8. An image conversion method for converting an input image into an output image,
A unit characteristic value calculating step for calculating a characteristic value relating to a unit representing each of the plurality of areas obtained by dividing the area of the input image as a unit characteristic value;
An image area characteristic value calculating step of calculating a characteristic value related to the image area as an image area characteristic value from a predetermined image area including at least a plurality of pixels adjacent to the unit;
Using the dark lookup table corresponding to the combination of the unit characteristic value and the image area characteristic value among a plurality of different dark lookup tables in which the dark luminance value is associated with each input luminance value, the input image is A dark image generating step of generating a dark image by converting the brightness value of each pixel constituting the dark brightness value corresponding to the brightness value;
Of each of the plurality of different bright look-up tables in which a bright brightness value equal to or higher than the dark brightness value corresponding to the input brightness value is associated with each input brightness value, the unit characteristic value and the image area characteristic value Bright image generation step of generating a bright image by converting the luminance value of each pixel constituting the input image into the bright luminance value corresponding to the luminance value using a bright lookup table corresponding to the combination When,
An image conversion method including an image generation step of generating the output image by mixing the bright image and the dark image for each unit.   8. A program for operating the image conversion apparatus according to claim 1, wherein the image conversion program causes a computer to function as each of the above-described means.   A computer-readable recording medium in which the image conversion program according to claim 11 is recorded.