JP2014140126A - Display device, television receiver, and display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device, a television receiver, and a display method that have desired chromaticity while suppressing a displayed image from becoming dark even when a white balance adjustment is made.SOLUTION: A television receiver stores a mathematical expression of Z=1.0×I×Sin(0.5×π×I) in a storage part. Here, Z is an output value and an I is a pixel value. As compared with a conventional expression of Z=I×, the stored mathematical expression has a large output value for each pixel value. Therefore, even when a white balance adjustment is made so as to decrease pixel values, output values for the decreased pixel values are large and an image is suppressed from decreasing in luminance.

Description

  The present invention relates to a display device, a television receiver, and a display method that improve chromaticity and brightness of an image.

  Display devices that display images based on received image data have been put into practical use. For example, a display device having a display unit composed of a liquid crystal panel has been put into practical use.

The display unit displays an image based on the output value obtained by correcting the pixel value of the received image data. In the display unit, the relationship between the pixel value of the received image data and the output value obtained by correcting to the pixel value is not necessarily proportional. This relationship that each display unit has is called display characteristics and is approximately expressed by Z = I ^γ (where Z: output value, I: pixel value, γ: power). A display unit using 2.2 as γ is often used (Patent Document 1).

When manufacturing a display device having a display unit using 2.2 as γ, the optical wavelength characteristics of the display unit, the influence of temperature, etc. are taken into consideration so as to obtain a configuration showing the relationship of the formula Z = ^I2.2. Design each component of the display device. Specifically, with respect to RGB (Y) of the received image data, when each of the R, G, and B pixel values is maximized, a predetermined chromaticity indicating white is obtained, and a medium value from a low pixel value is set. The design is performed so that the chromaticity can be kept constant over the entire gradation in the pixel value.

JP 2005-249891 A

  There are variations among display devices in color filters, backlights, and other elements that are components of the display device. Therefore, when a display device is manufactured by combining the components designed as described above, there is a possibility that the display device manufactured with the desired chromaticity may not show due to variations in the components.

In consideration of the above-described possibility, individual white balance adjustment is performed for each production line on the display device in which the components are combined. For example, in order not to reduce the luminance of the display device, the pixel values of R and B are changed from the relationship indicated by the equation Z = ^I2.2 with G as a reference. Specifically, white balance adjustment is performed, and the output values for R, G, and B are increased or decreased so that the chromaticity of a specified value is obtained at an appropriate position of each gradation.

  However, when such a white balance adjustment is performed, when the output value balance of R, G, and B representing white is not appropriate, a deviation occurs in the chromaticity of white in the video with respect to the high pixel value, and the color tone deteriorates. There is a risk of doing. As an improvement measure, a measure for reducing the level of the output value with respect to the G pixel value can be considered. However, since a decrease in output value means a decrease in luminance of the displayed image, the displayed image is displayed darkly as a countermeasure. Therefore, it cannot be said that the conventional display device can realize appropriate chromaticity based on white balance adjustment.

  The present invention has been made in view of such circumstances, and even when white balance adjustment is performed, a display device and a television that achieve a desired chromaticity while suppressing the displayed image from becoming dark It is intended to provide a John receiver and a display method.

The display device according to the present invention corrects the pixel value of each of the pixels constituting the image indicated by the image data received by the reception unit and the image data received by the reception unit. In a display device including a correction unit that performs correction and a display unit that displays an image based on the pixel value corrected by the correction unit, the correction unit performs correction represented by the following formula (1): Features.
Z = A × I ^N × Sin (0.5 × π × I) (1)
(However, Z: corrected pixel value, A: coefficient, I: pixel value, N: power)

In the display device described above, the pixel value of the received image data is corrected using Equation (1) Z = A × I ^N × Sin (0.5 × π × I), and the corrected pixel value is obtained. The based image is displayed on the display unit.

  The display device according to the present invention is characterized in that the N is 1.0 to 2.2.

  In the above-described display device, the power of Formula (1) used by the calculation unit is set in the range of 1.0 to 2.2.

  The display device according to the present invention is characterized in that the N is 1.3 to 1.7.

  In the above-described display device, the power of Formula (1) used by the calculation unit is set in the range of 1.3 to 1.7.

  A television receiver according to the present invention includes a receiving unit that receives a television broadcast and the above-described display device that displays an image of the television broadcast received by the receiving unit.

In the above-described television receiver, the pixel value of the image included in the received television broadcast is corrected using Equation (1) Z = A × I ^N × Sin (0.5 × π × I). Then, an image based on the corrected pixel value is displayed on the display unit.

The display method according to the present invention receives image data indicating an image composed of a plurality of pixels, corrects the pixel value of each pixel constituting the image indicated by the received image data, and performs the correction. In the display method for displaying an image based on the pixel value, the correction represented by the following formula (1) is performed.
Z = A × I ^N × Sin (0.5 × π × I) (1)
(However, Z: corrected pixel value, A: coefficient, I: pixel value, N: power)

In the display method described above, the pixel value of the received image data is corrected using Equation (1) Z = A × I ^N × Sin (0.5 × π × I), and the corrected pixel value is obtained. Display the based image.

In the present invention, an image based on Z = A × I ^N × Sin (0.5 × π × I) is displayed instead of Z = I ^N for the pixel value of the received image data. It is. In ^{Z = A × I N × Sin} (0.5 × π × I), compared with the Z = I ^N, the pixel value after correction in the high pixel value region of the image data received is increased. That is, since the brightness of the image depends on the pixel value after correction, the brightness of the image with respect to the high pixel value region approaching white increases. Therefore, even when white balance adjustment is performed and the corrected pixel value is lowered, relatively high luminance can be maintained, and the displayed image can be prevented from becoming dark.

It is a schematic diagram which shows the external appearance of a television receiver. It is the block diagram which showed the example of 1 structure of the television receiver. It is a graph for comparing and explaining a curve indicated by a mathematical formula stored in a storage unit and a curve indicated by a conventional mathematical formula Z = ^I2.2 . It is a flowchart which shows the process sequence of the signal processing part which calculates an output value from the pixel value of a video signal.

(Embodiment 1)
Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. An example of a television receiver having a function as a display device will be described.

  FIG. 1 is a schematic diagram showing the appearance of the television receiver 1. FIG. 2 is a block diagram illustrating a configuration example of the television receiver 1. The television receiver 1 includes a control unit 10, a video / audio input unit 11, a tuner unit 12, an AV switch 13, a signal processing unit 14, a display unit 15, a speaker 16, and a storage unit 17.

  The control unit 10 includes a microcomputer including a central processing unit (CPU), a storage medium (Read Only Memory: ROM), a memory (Random Access Memory: RAM), and the like. A control signal is given to the components to control the operation of each component.

  The video / audio input unit 11 is an input interface to which video signals and audio signals output from various external devices are input, and provides the input video signals and audio signals to the AV switch 13. The external device includes, for example, a tuner such as a satellite broadcast tuner, a cable TV tuner, and an IP broadcast tuner.

  The tuner unit 12 selects a broadcast signal of a specific channel from the broadcast signal received by the antenna A, and provides the AV switch 13 with a video signal and an audio signal included in the selected broadcast signal of the specific channel.

  The AV switch 13 selects either the video signal and audio signal given from the video / audio input unit 11 or the video signal and audio signal given from the tuner unit 12, and selects the selected video signal and audio signal. Output to the signal processing unit 14.

  The signal processing unit 14 generates video data based on the video signal output from the AV switch 13 and outputs the generated video data to the display unit 15. Specifically, the G, B, and R pixel values of the video signal received from the AV switch 13 are corrected with reference to a mathematical expression 17a stored in the storage unit 17 to be described later, and an output value (after correction) Pixel value) is calculated, video data based on the calculated output value is generated, and the generated video data is output to the display unit 15. Further, the signal processing unit 14 generates audio data based on the audio signal output from the AV switch 13 and outputs the generated audio data to the speaker 16.

  The display unit 15 is composed of a liquid crystal panel, and displays video based on video data provided from the signal processing unit 14. You may comprise using a plasma display panel, an organic electroluminescent panel, etc.

  The speaker 16 generates sound by changing the electrical signal into physical vibration, and outputs sound based on the sound data given from the signal processing unit 14.

The storage unit 17 is configured by a RAM, and stores a mathematical formula 17 a used for displaying an image by the display unit 15. Equation 17a is expressed by Z = 1.0 × I ^1.5 × Sin (0.5 × π × I) (where Z: output value, I: pixel value). The storage unit 17 may be configured by a recording medium other than the RAM, for example, an HDD.

FIG. 3 is a graph for comparing and explaining the curve represented by Expression 17a stored in the storage unit 17 and the curve represented by the conventional expression Z = ^I2.2 . The horizontal axis in FIG. 3 indicates the pixel value of the received image data, and the vertical axis indicates the output value of the received image data. A numerical value 1.0 on the horizontal axis indicates 100% with respect to the maximum value 255 of the number of pixels of received image data. A numerical value 1.0 on the vertical axis indicates 100% of the maximum output value.

In FIG. 3, a curve indicated by Z = I ^2.2 indicating the conventional relationship between the pixel value and the output value, and the equation 17a, Z = 1.0 × I ^1.5 × Sin (0.5 × A curve represented by π × I), a curve represented by Z = 1.0 × I ^1.0 × Sin (0.5 × π × I), which is an example in which the power of Equation 17a is changed, and a coefficient of Equation 17a Is a curve represented by Z = 0.9 × I ^1.5 × Sin (0.5 × π × I), which is an example of changing Z, and Z = Sin (0.5 × π × I), which is an example of other mathematical expressions And a curve represented by Z = 0.9 × I ^2.2 is shown.

The curve represented by Equation 17a, Z = 1.0 × I ^1.5 × Sin (0.5 × π × I) has a larger output value at each pixel value than the conventional curve represented by Z = I ^2.2. It has become. Since the luminance of the displayed image is changed in accordance with the output value, as compared with the curve shown in the conventional Z = I ^2.2, the image displayed at the same pixel value in the case of the curve represented by the equation 17a Increases the brightness.

As a method of executing white balance adjustment, a method of correcting the pixel value of received image data is known. In this method, in order to suppress a decrease in luminance of the displayed image, the B and R pixel values are corrected based on G. That is, considering G, the same correction is applied to the G, B, and R pixel values. When correction is made so that the pixel value increases, a saturation state occurs in the pixel value corresponding to white, and appropriate chromaticity cannot be realized, so correction is made so that the pixel value decreases. For example, when white balance adjustment is performed and a pixel value of 100% with an output value of 100% is reduced to a pixel value of 95%, the conventional Z = the output value is the curve indicated by I ^2.2 is in the 89%, the output value of the curve represented by the equation 17a is in the 92%. That is, when white balance adjustment is performed and the G, B, and R pixel values are set to 95%, the luminance decreases by 1.1% at the conventional Z = I ^2.2. Then, the luminance is reduced only by 0.8%. Therefore, by using Expression 17a, it is possible to suppress a decrease in luminance of the displayed image.

Even a curve represented by Z = 1.0 × I ^1.0 × Sin (0.5 × π × I), which is an example in which the power of Equation 17a is changed, is compared with a conventional curve represented by Z = I ^2.2 , The output value at each pixel value is large. For example, when white balance adjustment is performed and a pixel value of 100% with an output value of 100% is reduced to a pixel value of 95%, the conventional Z = the output value is the curve indicated by I ^2.2 is in the 89%, the output value of the curve represented by the equation of this example is a 95%. In other words, when white balance adjustment is performed and the pixel value of G, B, and R is 100% and the pixel value is 95%, the luminance decreases by 1.1% at the conventional Z = I ^2.2. Then, the luminance is reduced only by 0.5%. Therefore, by using the mathematical formula of this example, it is possible to suppress a decrease in luminance of the displayed image.

In the curve represented by Z = 0.9 × I ^1.5 × Sin (0.5 × π × I), which is an example in which the coefficient of Formula 17a is changed, the output value at each pixel value in the high pixel value region is the conventional value. It is smaller than the curve indicated by Z = ^I2.2 . In consideration of the fact that the output value in the curve represented by Z = 0.9 × I ^1.0 is smaller than the output value in the curve represented by Z = I ^2.2 , the coefficient of Equation 17a is preferably 1.0 or more.

A curve represented by Z = Sin (0.5 × π × I) is a curve greatly different from the conventional curve represented by Z = I ^2.2 and cannot be used because it does not match the display characteristics of the display unit 15. The fact is that it is not important to simply calculate Sin (0.5 × π × I), but 1.0 × I ^γ multiplied by Sin (0.5 × π × I) It is shown that the configuration with the output value is important.

FIG. 3 shows a modification of Formula 17a with a power of 1.5 and Formula 17a with a power of 1.0, but the power in the range of 1.0 to 2.2 is preferable. . Further, the number in the range of 1.3 to 1.7 is more preferable as the power. Even when a power number less than 1.3, the luminance than Z = I ^2.2 may become large, there is a captive become free image contrast. In addition, when the power is larger than 1.7, there is a captive that the adjustment likelihood for the maximum luminance is reduced.

As a method of executing the white balance adjustment, it is possible to consider a method in which different corrections are made on the G, B, and R pixel values. For example, the G pixel value is modified to be a curve represented by Z = I ^2.1 , the B pixel value is modified to be a curve represented by Z = I ^2.0 , and the R pixel value is Z = I ^1.9. It can be considered that the correction is made so that the curve shown in FIG. However, with such a method, it is difficult to match chromaticity in white corresponding to the maximum value of the pixel value and the output value of 100%.

  FIG. 4 is a flowchart showing the processing procedure of the signal processing unit 14 that calculates the output value from the pixel value of the video signal. The signal processing unit 14 receives a video signal from the AV switch 13 (step S11).

  The signal processing unit 14 calculates an output value for the pixel value of the received video signal based on the mathematical expression 17a stored in the storage unit 17 (step S12). Further, the signal processing unit 14 generates video data based on the calculated output value (step S13).

  The signal processing unit 14 outputs the generated video data to the display unit 15 (step S14), and ends the process. By performing this processing procedure, an image based on the generated video data is displayed on the display unit 15.

  With the above configuration, it becomes possible to use the television receiver 1 in which the output value with respect to the pixel value of the received image data is increased, and even when the output value is decreased by performing white balance adjustment, A sufficient output value can be secured. Therefore, even when white balance adjustment is performed, relatively high brightness can be maintained, and the displayed image can be prevented from becoming dark.

  The embodiments disclosed herein are illustrative in all respects and should not be considered as restrictive. The scope of the present invention is shown not only by the contents exemplified above but also by the scope of claims for patent, and it is intended to include all the updates within the meaning and scope equivalent to the scope of claims for patent.

DESCRIPTION OF SYMBOLS 1 Television receiver 10 Control part 11 Video / audio input part 12 Tuner part 13 AV switch 14 Signal processing part 15 Display part 16 Speaker 17 Memory | storage part

Claims (5)

A reception unit that receives image data indicating an image composed of a plurality of pixels, a correction unit that corrects a pixel value of each pixel included in the image indicated by the image data received by the reception unit, and the correction In a display device comprising a display unit that displays an image based on a pixel value corrected by the unit,
The said correction | amendment part performs correction | amendment represented by following Numerical formula (1). The display apparatus characterized by the above-mentioned.
Z = A × I ^N × Sin (0.5 × π × I) (1)
(However, Z: corrected pixel value, A: coefficient, I: pixel value, N: power) The display device according to claim 1, wherein N is 1.0 to 2.2. The display device according to claim 1, wherein the N is 1.3 to 1.7. A receiver for receiving television broadcasts;
A television receiver comprising: the display device according to any one of claims 1 to 3 that displays an image of a television broadcast received by the receiving unit. Accepts image data indicating an image composed of a plurality of pixels, corrects the pixel value of each pixel constituting the image indicated by the received image data, and displays an image based on the corrected pixel value In the display method,
The display method characterized by performing correction represented by the following mathematical formula (1).
Z = A × I ^N × Sin (0.5 × π × I) (1)
(However, Z: corrected pixel value, A: coefficient, I: pixel value, N: power)

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