JPH08317321A - Image display device - Google Patents

Abstract

PURPOSE: To provide an image display device with which a CG image can be also displayed with high definition together with a TV image by providing a first correction table part corresponding to NTSC and a second correction table part storing correction characteristic data different from those of the first correction table part. CONSTITUTION: When a TV image signal is inputted to a selecting part 1, the selecting part 1 selects the TV image signal based on a switching signal supplied from the outside and a correction table part 4 for TV signal is selected. When a CG image signal is inputted to the selecting part 1, on the other hand, the selecting part 1 selects the CG image signal based on the switching signal supplied from the outside and a correction table part 5 for CG signal is selected. Therefore, since the R, G and B signals of the CG image signal having passed through an A/D converting part 2 and a signal processing part 3 are corrected by the correction characteristic data, whose gamma value is almost 2.2, stored in the correction table part 5 for CG signal, even when those signals are displayed on a display such as a PDP, they can be displayed without any change from the hue of the source image.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a PDP (Plasma Display).
The present invention relates to an image display device for supplying a corrected image signal to a display having a linear (straight line) relationship in display (electrical-optical conversion) characteristics such as Panel) to improve the display image quality.

[0002]

2. Description of the Related Art In recent years, PDPs are excellent in large screen characteristics among flat displays, and are capable of full-color display and high-speed gradation display, so that they can be used as thin large-screen color image display devices. It has begun.

By the way, a CRT (cathode ray tube) is mainly used as a color image display device at present, and the display (electrical-optical conversion) characteristics of this CRT have an input signal level (X) and an output signal (light emission). The relationship with the level (Y) is such that Y is proportional to X to the power of γ (gamma). Since this γ (gamma) is approximately γ = 2.2, the original (TV) signal obtained by the camera on the transmission side has the γ ′ value of the inverse characteristic of γ (gamma), that is, γ ′ = 0.45. Will be corrected. When the corrected signal is supplied to the CRT, the luminance, hue, and color saturation (saturation) are correct on the screen, Y is displayed in a substantially linear relationship with X, and the original image can be reproduced. .

On the other hand, in a display such as a PDP which displays a gradation by an image signal subjected to pulse number modulation, the relationship between X and Y has a linear characteristic and gamma is 1. Therefore, when trying to perform a correct color display equivalent to that of a CRT on a PDP having a linear input-output characteristic, the above γ '= 0.
An input signal corrected with a value of 45 (for example, corrected with a value of γ '= 0.45 for each R, G, B signal) is given by γ = 2.
It is necessary to reverse-correct with a value of 2 and supply it to the PDP.

A specific description will be given. FIG. 4 shows an example of a conventional image display device. Incidentally, a similar example is shown in JP-A-3-18823. Reference numeral 2 is an AD conversion unit that converts an image signal into a digital signal, and 3 is, for example, a VGA (Video Grahics Array: 640 × 480) for displaying on a PDP.
(Dot) is a signal processing unit that performs format conversion to a standard, and 14 is a correction table unit that stores correction characteristic data and inputs a signal to be corrected to output corresponding data from the correction characteristic data. is there. Reference numeral 6 denotes a brightness detection unit that calculates the average brightness of one field of the image signal and detects the average brightness.

In the above structure, a TV signal is input,
The TV signal is converted into a digital signal by the AD conversion unit 2, the required signal processing is performed by the signal processing unit 3, and the so-called gamma correction as shown in (a) of FIG. Correct with the characteristics. Incidentally, JP-A-6-261
As disclosed in 335, this gamma correction characteristic mainly focuses on the input characteristic of the intermediate level, which is the most conspicuous on the PDP screen, for example, by correcting the intermediate level with a value such as a gamma value of 3, so that the contrast ratio is mainly increased. This is a correction for enlargement. Further, when the input image is dark as a whole, when the image has an average brightness, and when the input image is bright as a whole, the brightness detection unit 6 detects the respective cases, and as shown in (b) of FIG. A proper characteristic is selected from the three gamma correction characteristics and the correction is performed.

However, in recent years, image signals displayed on the PDP have been diversified, and in addition to conventional TV signals, for example, C
There is a demand to display a composite image generated based on data, such as a G (Computer Graphics) image. This CG signal has not been corrected by the gamma value γ '= 0.45 similar to the above TV signal. When the correction table unit 14 performs the reverse correction similar to that of the TV signal, the R, G, B signals forming the original CG image signal are subjected to the gamma correction having the nonlinear characteristic. Therefore, as shown in FIG. 6, in the image data having the saturation in the CG image signal, the data is changed at a different ratio for each R, G, B signal, so that the hue of the image displayed on the PDP is the same as the original one. There is a problem that the displayed image is deteriorated, such as being displayed in a different color from that of the image. It should be noted that, even in the case of a TV signal, although the phenomenon in which the hue of the original image changes to some extent, since there are many still images in the CG image, the change in hue directly leads to the deterioration of the displayed image, whereas in the TV image, a moving image appears. Since there are many, deterioration is not noticeable.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an image display device capable of displaying a CG image as well as a TV image in high quality.

[0009]

To achieve the above object, an AD converter for converting an input image signal into a digital signal, a signal processor for performing necessary processing on the digital signal, and the signal processor. In the image display device, which comprises a correction table unit for storing correction characteristic data for correcting the output of the above, the correction table unit is a first correction table unit corresponding to NTSC, and correction characteristic data different from the first correction table unit is stored. Two correction table units are provided.

An AD conversion unit for converting an input image signal into a digital signal, a signal processing unit for performing required processing on the digital signal, and correction characteristic data for correcting the output of the signal processing unit are stored. In an image display device comprising a correction table unit, the correction table unit is provided with a first correction table unit corresponding to NTSC and at least one correction table unit storing correction characteristic data different from the first correction table unit, and a plurality of correction table units are provided. A selection unit for selecting one from the input image signals is provided, and a correction table unit corresponding to the image signal selected by the selection unit is selected to correct the image signal.

[0011]

With the above construction, when the NTSC-TV signal is supplied, the correction is made based on the so-called gamma correction data stored in the first correction table section. C
When the G signal or the like is supplied, the correction is performed based on the correction characteristic data stored in at least one correction table section that stores the correction characteristic data different from the second correction table section or the first correction table section.

[0012]

EXAMPLE An image display device according to the present invention will be described below.
This will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of an image display device according to the present invention. Reference numeral 1 is a selection unit for selecting either a TV image signal or a CG image signal.
Reference numeral 2 denotes an AD conversion unit that converts the image signal selected by the selection unit 1 into a digital signal. Reference numeral 3 denotes a signal processing unit that performs necessary processing on the digital signal, for example, processing such as format conversion to the VGA standard. Reference numeral 4 denotes a TV in which correction characteristic data for appropriately correcting the output of the signal processing unit 3 is a TV image signal.
It is a signal correction table section. Reference numeral 6 denotes a brightness detection unit that calculates the average brightness of one field of the image signal and detects the average brightness. Reference numeral 5 denotes a CG signal correction table unit that stores correction characteristic data for appropriately correcting the output of the signal processing unit 3 when the output is a CG image signal.

FIG. 2 is a block diagram of an embodiment of the R, G, B correction section which constitutes the correction table section of the image display device according to the present invention. Reference numeral 21 denotes a TV signal R signal correction table unit 24 for storing R signal correction characteristic data for correcting the TV image signal, and CG for storing R signal correction characteristic data for correcting the CG image signal. This is an R signal correction unit composed of a signal R signal correction table unit 25. Two
Reference numeral 2 is a G signal correction unit having the same configuration. 23 is
It is a B signal correction unit configured in the same manner.

The signal correction operation of the image display device according to the present invention will be described with reference to FIGS. 1, 2 and 3. Incidentally, the same parts as those in the conventional example of FIG. When the CG image signal composed of the primary color R, G, B signals is input to the selection unit 1, the selection unit 1 selects the CG image signal based on the switching signal supplied from the outside, and
The CG signal correction table unit 5 is selected. The R, G, and B signals of the digital signal based on the CG image signal that has passed through the AD conversion unit 2 and the signal processing unit 3 are, for example, the R signal correction table 15 that constitutes the CG signal correction table unit 5.
Is supplied to the corresponding correction table.

However, since the CG image signal is generally produced by using a CRT monitor, the C
The G image signal is in a state of being corrected with a characteristic opposite to the light emission characteristic of the CRT monitor (A curve in FIG. 3) as shown by the B curve in FIG. When such a CG image signal is supplied to the correction table, each correction table composed of the ROM is based on a curve having a gamma value of approximately 2.2 as shown by the curve A in FIG. Since the correction characteristic data in the table format in which 256 correction outputs are made to correspond to the input of is stored, the R, G, B signals of the CG image signal are corrected to form the C curve of FIG. The original image is reproduced by converting the data into linear data as shown. still,
When the light emission characteristics of the CRT monitor are different for the R, G, and B signals, the correction characteristic data of each correction table can be different corresponding data.

[0016]

As described above, the present invention provides an image display device capable of displaying not only TV images but also CG images in high quality. Therefore, even if a composite image generated based on data, such as a CG image, is displayed on the PDP, the hue of the image displayed on the PDP has an advantage of being displayed without changing from the hue of the original image.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an image display device according to the present invention.

FIG. 2 is a block diagram of an embodiment of R, G, and B correction sections that constitute a correction table section of the image display device according to the present invention.

FIG. 3 is a diagram showing a light emission characteristic of a CRT monitor and an inverse characteristic thereof for explaining a signal correction operation of the image display device according to the present invention.

FIG. 4 is an example of a conventional image display device.

FIG. 5 is a diagram showing gamma correction characteristics for explaining a correction operation of an image signal in the embodiment of the conventional image display device.

FIG. 6 is a diagram illustrating an operation in which image data having saturation is changed by a conventional gamma correction at a different rate for each R, G, and B signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 selection unit 2 AD conversion unit 3 signal processing unit 4 TV signal correction table unit 5 CG signal correction table unit 6 brightness detection unit 14 correction table unit 21 R signal correction unit 22 G signal correction unit 23 B signal correction unit 24 TV Correction table part for R signal of signal 25 Correction table part for R signal of CG signal

Claims (6)

[Claims] 1. An AD conversion unit for converting an input image signal into a digital signal, a signal processing unit for performing required processing on the digital signal, and correction characteristic data for correcting the output of the signal processing unit. In the image display device, the correction table unit is provided with an NTSC-compatible first correction table unit and a second correction table unit storing different correction characteristic data. . 2. An AD conversion unit for converting an input image signal into a digital signal, a signal processing unit for performing required processing on the digital signal, and correction characteristic data for correcting the output of the signal processing unit. In the image display device including the corrected correction table section, the correction table section is provided with a first correction table section corresponding to NTSC, and at least one correction table section storing different correction characteristic data, An image display characterized by comprising a selecting section for selecting one from a plurality of input image signals, and selecting a correction table section corresponding to the image signal selected by the selecting section to correct the image signal. apparatus. 3. An image display device in which correction characteristic data having a gamma (γ) value of approximately 2.2 is stored in the second correction table section according to claim 1 and at least one correction table section according to claim 2. 4. The second correction table section according to claim 1 and at least one correction table section according to claim 2 are composed of a correction table in which required correction characteristic data is stored for each of the primary color R, G and B signals. Image display device. 5. An image display device in which required correction characteristic data provided for each of the primary color R, G, B signals according to claim 4 is the same correction characteristic data for all R, G, B signals. 6. The second correction table unit according to claim 1 and at least one correction table unit according to claim 2 are RO
An image display device composed of M.