JP2015220721A - Display device, image signal processing device and image signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device in which circuits for edge emphasis processing and signal processing of RGB + fourth color are scaled down.SOLUTION: With respect to a display pixel unit in which sub pixels of fourth color having high brightness as well as red, green and blue are arranged, and the respective sub pixels are driven on the basis of pixel signals of corresponding colors, a fourth color image signal is generated from image signals of red, green and blue, the fourth color image signal is modulated according to an indicated modulation level, modulation processing is executed on the red, green and blue image signals on the basis of the modulation output of the fourth color image signal, and the modulated red, green and blue image signals are output to the display pixel unit together with the fourth color image signal. At this time, edge information is extracted from the fourth color image signal, and the edge amount is controlled on the basis of an indicated gain from the edge information, and the edge amount is added to the fourth color image signal to thereby emphasize the edge of the display image.

Description

  Embodiments described herein relate generally to a display device, an image signal processing device, and an image signal processing method that emphasize edges of a display image.

In recent display devices, various technologies for adjusting brightness, contrast, etc. to the optimum state by the input image signal so that an image can be displayed in an appropriate state as its functionality and versatility are increased. Has been developed.
For example, Patent Document 1 aims to keep the luminance of a display screen constant with respect to a change in display content by detecting a white luminance ratio in an input image signal and feeding back a detection result to a luminance adjustment circuit. Have been disclosed. Further, Patent Document 2 discloses a proposal that can realize higher image quality and higher visibility by controlling the degree of enhancement with respect to an edge according to an image and a viewing environment using an edge enhancement function. .

  On the other hand, for example, in Patent Document 3, four colors are obtained by adding white (W; White) as a fourth color to three colors of red (R; Red), green (G; Green), and blue (B; Blue). An RGBW display device that uses subpixels to display unit pixels by driving so-called RGBW subpixels is disclosed. According to this RFBW display device, the input RGB image signal is converted into the RGBW image signal, whereby the brightness is improved, and as a result, the power consumption can be reduced.

  Here, in the RGBW display device, when performing edge enhancement, before converting the RGB image signal to the RGBW image signal, the luminance information is extracted from the RGB image signal, and the edge information is detected from the luminance information. The edge amount of the RGB image signal is controlled based on the edge information and the illuminance information of external light. In this configuration, edge enhancement processing is completely independent of RGBW signal processing, but since both are processed based on luminance information, it is desired to reduce the circuit scale by sharing the circuit configuration.

JP-A-7-129113 JP 2011-29870 A Japanese Patent No. 5386211

As described above, in the conventional display device in which the fourth color is added to the three RGB colors, the edge enhancement processing is completely independent of the RGB + fourth color signal processing, and the circuit configuration is shared. Reduction in scale is desired.
Therefore, in the present invention, the circuit scale of the edge enhancement processing and the RGB + fourth color signal processing is reduced, thereby realizing a reduction in cost and more easily realizing a display with high functionality and low power consumption. Let it be an issue.

  The display device of this embodiment includes a display pixel unit and a signal processing unit. The display pixel unit uses unit pixels in which sub-pixels of a fourth color having higher luminance than red, green, and blue are arranged in addition to red, green, and blue, and images of colors corresponding to the sub-pixels. Unit pixels are displayed by driving based on the signal. The signal processing unit generates the fourth color image signal from the input red, green, and blue image signals, modulates the fourth color image signal according to a specified modulation level, and outputs the fourth color image signal. The red, green, and blue image signals are modulated based on the modulation output of the color image signal, and the red, green, and blue image signals after the modulation process are displayed together with the fourth color image signal. An image conversion unit for outputting to the pixel unit is provided. The signal processing unit includes an edge enhancement processing unit, and the edge enhancement processing unit is based on an edge information extraction unit that extracts edge information from the image signal of the fourth color, and a specified gain from the edge information. An edge amount control unit that controls an edge amount; and an addition unit that adds the edge amount to the image signal of the fourth color.

The image signal processing apparatus according to the present embodiment uses unit pixels in which sub-pixels of the fourth color having higher luminance than red, green, and blue are arranged in addition to red, green, and blue, and each sub-pixel is supported. The fourth color image signal is used for a display device having a display pixel unit that displays unit pixels by driving based on the color image signal. Generating, modulating the image signal of the fourth color according to a specified modulation level, and performing modulation processing of the red, green, and blue image signals based on the modulation output of the image signal of the fourth color. An image conversion unit that outputs the processed red, green, and blue image signals together with the fourth color image signal to the display pixel unit, and further extracts edge information from the fourth color image signal; From the edge information extraction unit and the edge information It comprises an edge amount control unit for controlling the edge amount based on the constant-gain, an addition unit for adding the edge quantity to the image signal of the fourth color.
In addition to red, green, and blue, output sub-pixels of a predetermined color are further arranged to expand the signal level of the input image signal to the display pixel unit constituting the unit pixel, and the expanded red, green, and blue The signal component of the predetermined color is extracted from the signal of the predetermined color, the signal level of the predetermined color is determined, the expansion process is performed based on the determined signal level of the predetermined color, and red, green, blue after the expansion process is performed The signal is modulated in accordance with a predetermined modulation level and output to the display pixel unit, edge information is extracted from the signal component of the predetermined color, an edge amount is controlled based on a specified gain from the edge information, and The edge amount is added to the signal component of the predetermined color.

  The image signal processing method of this embodiment uses unit pixels in which sub-pixels of a fourth color having higher luminance than red, green, and blue are arranged in addition to red, green, and blue, and each sub-pixel is supported. The fourth color image signal is used for a display device having a display pixel unit that displays unit pixels by driving based on the color image signal. Generating, modulating the image signal of the fourth color according to a specified modulation level, and performing modulation processing of the red, green, and blue image signals based on the modulation output of the image signal of the fourth color. When the processed red, green, and blue image signals are output to the display pixel unit together with the fourth color image signal, edge information is extracted from the fourth color image signal, and the edge information is extracted from the edge information. Control edge amount based on specified gain, Emphasizing the edge of the display image the serial edge amount is added to the image signal of the fourth color.

The block diagram which shows the whole structure of the display apparatus which concerns on this embodiment. The block diagram which shows the structure of the signal processing part of the display apparatus shown in FIG. The block diagram which shows the other structure of the signal processing part of the display apparatus shown in FIG.

The best mode for carrying out the present invention (hereinafter simply referred to as an embodiment) will be described below in detail with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an RGBW type display device according to an embodiment of the present invention. The RGBW display device shown in FIG. 1 includes a host computer (processor) 1 that controls the whole, an interface 2, a signal processing unit 3, a gate driver 4, a source driver 5, a display pixel unit 6, a backlight control unit 7, a backlight. 8 is provided.

  In this configuration, the interface 2, the signal processing unit 3, the gate driver 4, the source driver 5, and the backlight control unit 7 form a part of an integrated circuit (IC). The R (Red), G (Green), and B (Blue) signals of the display image output from the host computer 1 are input to the signal processing unit 3 via the interface 2 as input image signals Rin, Gin, and Bin, respectively. Supplied.

  The signal processing unit 3 converts the image signals Rin, Gin, Bin input from the host computer 1 via the interface 2 into RGBW signals (addition of W (White)), and outputs the output image signals Rout, Gout, Bout, It is sent to the source driver 5 as Wout. At the same time, control signals such as a vertical synchronization signal, a horizontal synchronization signal, and a backlight control signal for displaying an RGBW image are generated from the RGB signals, and these control signals are respectively generated as a gate driver 4, a source driver 5, and a backlight control unit. 7 is supplied.

  The gate driver 4 performs on / off control of a thin film transistor (TFT) corresponding to each pixel of the display pixel unit 6 based on a control signal from the signal processing unit 3. Based on the control signal from the signal processing unit 3, the source driver 5 holds digital signals of R, G, B, and W as image signals in a holding unit provided therein, and sequentially supplies them to the display pixel unit 6. Output. The backlight control unit 7 drives and controls the backlight 8 based on the backlight control signal from the signal processing unit 3.

  Here, the display pixel unit 6 includes, for example, m (m = 1, 2,...) Pixels in the horizontal direction and n (n = 1, 2,...) M × n pixels in the vertical direction. This is a liquid crystal display (LCD) arranged in a matrix. The display pixel unit 6 can display predetermined information as an image by changing the transmittance of light emitted from the backlight 8 in the liquid crystal layer based on the control of the backlight control unit 7. ing.

  One pixel as a unit of display resolution is composed of four pixels of R (Red), G (Green), B (Blue), and W (White). Hereinafter, a pixel as a unit of display resolution composed of three RGB pixels and further W pixels is referred to as a “pixel”, and each RGBW pixel constituting the pixel is referred to as a “sub-pixel”. Translucent color filters of red, green, and blue are arranged in the portion corresponding to the RGB subpixel, and transparent filters are arranged in the portion corresponding to the W subpixel.

Next, details of the signal processing unit 3 will be described with reference to FIG.
FIG. 2 is a block diagram illustrating a configuration of the signal processing unit 3. As shown in FIG. 2, the signal processing unit 3 includes a gamma processing unit 31, an image analysis and RGBW conversion unit (hereinafter abbreviated as an image analysis unit) 32, an inverse gamma processing unit 33, an edge enhancement processing unit 34, and The external light detection unit 35 is included.

  In such a configuration, the gradation-luminance characteristics of the RGB image signals Rin, Gin, Bin sent through the interface 2 are compressed along the gamma curve. For this reason, it is supplied to the gamma processing unit 31, is calculated so that the gradation-luminance characteristics have a linear relationship, and is output to the image analysis unit 32 as image information R1, G1, B1.

The image analysis unit 32 analyzes the gamma-processed image information, reads information necessary for RGBW conversion, and sequentially converts the R1, G1, B1 signals into R2, G2, B2, W2 signals using the information. And output.
Here, the white image signal W2 is generated from the red, green, and blue input image signals R1, G1, and B1, and the brightness is adjusted by modulating the white image signal W2 according to the specified modulation level, and at the same time, the light source Adjust the brightness of (Backlight). Then, the red, green, and blue image signals are modulated based on the modulation output of the white image signal, and the red, green, and blue image signals after the modulation processing are R2, G2, and B2 together with the white image signal. , Output as W2 signal.

The R2, G2, B2, and W2 signals generated in this way are arithmetically processed again by the inverse gamma processing unit 33 so as to have the inverse gamma characteristic, and are input to the display pixel unit 6 as RGBW signals Rout, Gout, Bout, and Wout. Sent.
In the signal processing unit 3 configured as described above, an embodiment of the present invention includes an edge enhancement processing unit 34 and an external light detection unit 35 as shown in FIG. The edge enhancement processing unit 34 includes an edge information extraction unit 341, an edge amount control unit 342, and an addition unit 343.

The edge information extraction unit 341 takes in the W2 signal obtained by the image analysis unit 32 and obtains an edge signal Yedge (n) from the following equation. Note that n−1, n, and n + 1 indicate horizontal pixel positions.
Yedge (n) = -1 / 2 × W2 (n-1) + W2 (n) -1 / 2 × W2 (n + 1) (1)
Next, the edge amount control unit 342 determines the gain Gain based on the illuminance information of the external light detected by the external light detection unit 35 based on the edge signal Yedge (n) extracted by the edge information extraction unit 341, and then Adjust the edge amount from the formula.
Y1edge (n) = Yedge (n) x Gain (2)
The edge amount Y1edge (n) is sent to the adder 343, and is added to the W2 (n) signal obtained by the image analyzer 32 as shown in the following equation to be converted into a W3 (n) signal, which is an inverse gamma process. The edge amount is increased only for white pixels.
W3 (n) = W2 (n) + Y1edge (n) (3)
That is, in the configuration of the above embodiment, the panel having RGBW pixels generates white data, so that edge enhancement is performed on white data that does not have color information, thereby eliminating the need for luminance information extraction. Further, since the edge amount only needs to be added to white pixels, the circuit scale can be reduced by reducing the number of multipliers and adders required for RGB.

  Incidentally, in the configuration of the above embodiment, edge enhancement processing is performed before inverse gamma processing at the image analysis stage, but the present invention is not limited to this. For example, as shown in FIG. The edge enhancement processing unit 34 and the external light detection unit 35 shown in FIG. 2 may be provided after the processing unit 33.

  In this case, the W2 signal obtained by the image analysis unit 32 is sent as it is to the inverse gamma processing unit 33, and the W4 signal subjected to the inverse gamma processing by the inverse gamma processing unit 33 is supplied to the edge information extraction unit 341 and the addition unit 343. Will be. For this reason, said (1)-(3) Formula is changed into the following (4)-(6) Formula.

Yedge (n) = -1 / 2 × W3 (n-1) + W3 (n) -1 / 2 × W3 (n + 1) (4)
Y1edge (n) = Yedge (n) x Gain (5)
Wout (n) = W3 (n) + Y1edge (n) (6)
As described above, the present invention can be applied even after the inverse gamma processing unit. In this case, for example, the calculation is 14 to 16 bits before the inverse gamma processing, but there is an advantage that the calculation of 8 to 10 bits is sufficient after the inverse gamma processing.
In the above-described embodiment, the case where White is used as the fourth color in addition to RGB has been described. However, the present invention is not limited to this, and similar components can be used as long as they have relatively high luminance such as Yellow and cyan. It is possible to produce an effect.

Moreover, in the said embodiment, although the gain which adjusts edge amount was determined based on the illumination intensity information detected by the external light detection part 35, you may make it a user set arbitrarily, for example.
In the above embodiment, the case where the display pixel unit is a liquid crystal display panel has been described.

  In addition, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 ... Host computer (processor)
2 ... interface,
3 ... signal processing unit,
DESCRIPTION OF SYMBOLS 31 ... Gamma processing part, 32 ... Image analysis and RGBW conversion part (image analysis part), 33 ... Inverse gamma processing part, 34 ... Edge emphasis processing part, 341 ... Edge information extraction part, 342 ... Edge amount control part, 343 ... Addition unit, 35 ... outside light detection unit,
4 ... Gate driver,
5 ... Source driver,
6 ... display pixel part,
7 ... Backlight control unit,
8 ... Backlight

Claims (9)

In addition to red, green, and blue, unit pixels in which sub-pixels of the fourth color having higher luminance than red, green, and blue are arranged, and each sub-pixel is driven based on the image signal of the corresponding color. A display pixel unit for displaying unit pixels,
The fourth color image signal is generated from the input red, green, and blue image signals, the fourth color image signal is modulated in accordance with a specified modulation level, and the fourth color image signal An image that performs red, green, and blue image signal modulation processing based on the modulation output, and outputs the red, green, and blue image signals after the modulation processing together with the fourth color image signal to the display pixel unit. A signal processing unit including a conversion unit,
The signal processing unit includes an edge enhancement processing unit,
The edge enhancement processing unit
An edge information extraction unit that extracts edge information from the image signal of the fourth color;
An edge amount control unit for controlling an edge amount based on a specified gain from the edge information;
A display device comprising: an adder that adds the edge amount to the image signal of the fourth color. The signal processing unit
A gamma processing unit that performs gamma processing on the input red, green, and blue image signals at a preceding stage of the image conversion unit;
A reverse gamma processing unit that performs reverse gamma processing on the image signals of the red, green, blue, and fourth colors at a subsequent stage of the image conversion unit,
The display device according to claim 1, wherein the edge enhancement processing unit performs processing on the fourth color image signal output from the image conversion unit and outputs the processed signal to the inverse gamma processing unit. The signal processing unit
A gamma processing unit that performs gamma processing on the input red, green, and blue image signals at a preceding stage of the image conversion unit;
A reverse gamma processing unit that performs reverse gamma processing on the image signals of the red, green, blue, and fourth colors at a subsequent stage of the image conversion unit,
The display device according to claim 1, wherein the edge enhancement processing unit processes the fourth color image signal output from the inverse gamma processing unit and outputs the processed signal as an output of the inverse gamma processing unit.   The display device according to claim 1, wherein the edge amount control unit determines the gain based on external light illuminance information. In addition to red, green, and blue, unit pixels in which sub-pixels of the fourth color having higher luminance than red, green, and blue are arranged, and each sub-pixel is driven based on the image signal of the corresponding color. It is used for a display device including a display pixel unit that displays unit pixels.
The fourth color image signal is generated from the input red, green, and blue image signals, the fourth color image signal is modulated in accordance with a specified modulation level, and the fourth color image signal An image that performs red, green, and blue image signal modulation processing based on the modulation output, and outputs the red, green, and blue image signals after the modulation processing together with the fourth color image signal to the display pixel unit. An image signal processing apparatus including a conversion unit,
An edge information extraction unit that extracts edge information from the image signal of the fourth color;
An edge amount control unit for controlling an edge amount based on a specified gain from the edge information;
An image signal processing apparatus comprising: an adder that adds the edge amount to the image signal of the fourth color. Furthermore, a gamma processing unit that performs gamma processing on the input red, green, and blue image signals in the previous stage of the image conversion unit;
A reverse gamma processing unit that performs reverse gamma processing on the image signals of the red, green, blue, and fourth colors at a subsequent stage of the image conversion unit,
The image signal processing apparatus according to claim 5, wherein the fourth color image signal output from the image conversion unit is processed and output to the inverse gamma processing unit. Furthermore, a gamma processing unit that performs gamma processing on the input red, green, and blue image signals in the previous stage of the image conversion unit;
A reverse gamma processing unit that performs reverse gamma processing on the image signals of the red, green, blue, and fourth colors at a subsequent stage of the image conversion unit,
The image signal processing apparatus according to claim 5, wherein the fourth color image signal output from the inverse gamma processing unit is processed to be output from the inverse gamma processing unit.   The image signal processing apparatus according to claim 5, wherein the edge amount control unit determines the gain based on ambient light illuminance information. In addition to red, green, and blue, unit pixels in which sub-pixels of the fourth color having higher luminance than red, green, and blue are arranged, and each sub-pixel is driven based on the image signal of the corresponding color. It is used for a display device including a display pixel unit that displays unit pixels.
The fourth color image signal is generated from the input red, green, and blue image signals, the fourth color image signal is modulated in accordance with a specified modulation level, and the fourth color image signal An image that performs red, green, and blue image signal modulation processing based on the modulation output, and outputs the red, green, and blue image signals after the modulation processing together with the fourth color image signal to the display pixel unit. A signal processing method comprising:
Extracting edge information from the image signal of the fourth color;
Control the edge amount based on the specified gain from the edge information,
An image signal processing method for enhancing an edge of a display image by adding the edge amount to the image signal of the fourth color.

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