JP2001154653A - Digital picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrally handle a color picture and a monochrome picture and to eliminate the degradation of picture quality in a digital picture display device. SOLUTION: When a monochrome picture is displayed on a color liquid crystal display device 5, an upper one byte and a lower one byte among monochrome picture data are stored respectively in a first frame memory 11 and a second frame memory 12. The output signal of a color picture frame buffer 2 is inputted to a color/monochrome picture signal converting circuit 3 to be disassembled into three routes of 8-bit digital picture signals and vertical and horozontal syncbronizing signals and picture signals from frame memories 11, 12 among them are inputted to a LUT(line unit) 17 to be converted into 8-bit picture data. The 8-bit picture data are copied into three routes of picture output data having the same values as those of R, G, B in a digital video signal output circuit 19 and they are multiplexed with synchronizing signals to be inputted to the color liquid crystal display device 5 and they are displayed on the device 5 as the monochrome picture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image display device for displaying an image from a digital signal using an image frame buffer and an image display device.

[0002]

2. Description of the Related Art When displaying a digital image signal processed by a computer, a video signal is generated by writing the image data into an image frame memory, and is expressed on a display device such as a CRT. When a color image is displayed, R, G, and B luminance signals, which are the three primary colors of light, are generated in an image frame memory and input to a display device. In general, a luminance signal of each color of RGB is provided with 8-bit quantization precision, thereby realizing 256 gradations of each color, that is, a color resolution of 16 million colors in general, and is a means for expressing a full-color image. In a display device using a conventional CRT, an analog video input is suitable because an electron beam is continuously scanned. Until now, it has been common to use analog video signals to connect the image frame memory to the display device. However, when a video signal is transmitted as an analog signal, noise is picked up on a transmission path, resulting in image deterioration.

In the case of using a liquid crystal display device that has recently become widespread, each pixel is arranged discretely in a grid, and the control of luminance is performed discretely for each pixel. Therefore, when the image frame buffer and the liquid crystal display device are connected by a conventional analog interface, it is necessary to sample the analog signal input to the liquid crystal monitor again in discrete time. Normally, this is performed by the A / D converter on the liquid crystal monitor side. However, if the clock phases of both the D / A converter on the image frame buffer side and the A / D converter on the monitor side do not match, the jitter is increased. And moiré are generated, and the image quality is deteriorated. Therefore, a method using a digital interface for connection between an image frame buffer and a display device has recently been adopted on the assumption that a liquid crystal display device is connected.

FIG. 5 is a configuration diagram of a conventional color image display device using a digital video interface.
Each of the three frame memories 21, 22, and 23 corresponding to RGB colors in the digital video signal output circuit 6 receives 8-bit 256-gradation image data from the data bus 1, and holds the image data therein. The image data is sequentially read out for each frame period, and look-up table memories (LUs) corresponding to the respective RGB colors are used.
T) 25, 26, 27. The look-up table memories 25, 26, and 27 are 256-element table memories that output the contents of the memory with the input 8-bit value as an address. Used. The overlay memory 24 holds an image such as a cursor pointer which is superimposed on the image and displayed with priority. The image data output from the LUTs 25, 26, and 27 after the luminance values are converted are logically operated on the data in the overlay memory 24 by overlay operation circuits 29, 30, and 31, respectively.
If there is a non-zero value on the 4 side, that value takes precedence.
The signal value of the T-converted RGB image signal is output.

The output image data from the overlay circuits 29, 30, and 31 is input to a digital video signal output circuit 32, where it is multiplexed with the horizontal / vertical synchronization signals generated by the synchronization signal generator 28, and It is formed into a format and transmitted to the color display monitor 7.

On the other hand, in an image frame buffer for displaying a monochrome image typified by a medical X-ray image, the number of signal systems in the frame memory is merely three for color, but only one for monochrome. , And the circuit configuration is particularly different with respect to the gradation accuracy of the image data.

[0007] In a color image, 1600 even for 8 bits for each color
It is possible to display all colors, and it is considered that the gradation accuracy of the image data itself is 8 bits for each color. On the other hand, for a monochrome image, 256 gradations of a single color are not enough, and 10 bits or 12 bits Is used. At the time of display, the image data is converted into an 8-bit or 10-bit image signal that can be expressed by a display device through an LUT and displayed.

In a medical X-ray image which is a representative example of image data for displaying a monochrome image, the data itself has an information amount of 12 bits = 4096 gradations. For display, general 8-bit = 256 gradation display and 10-bit = 1024 gradation display that can be visually identified are used. Further, in order to display a specific portion or a region of a specific luminance in an easily viewable manner, an image is widely displayed while changing luminance and contrast.

FIG. 6 is a configuration diagram of a conventional example of a monochrome image display device using an analog video interface. Since the monochrome display device has a large number of CRTs, it is exclusively used to connect a frame buffer and a display monitor using a conventional analog video interface. 12-bit image data per pixel is
The data is written to the monochrome frame memory 41 in the monochrome image frame buffer 8 through the data bus 1, and stored in the monochrome frame memory 41 through the look-up table memory (LUT) 43.
It is converted to bit image data. The converted image data is superimposed on the contents of the overlay frame memory 42 by an overlay operation circuit 44, and the result is D / A
Send to converter 45. The D / A converted video output signal is displayed on a monochrome CRT monitor 9. The horizontal / vertical synchronization signal generated by the synchronization signal generator 46 is connected to the monochrome CRT monitor 9 via another analog signal line. To change the brightness / contrast of the displayed image, the contents of the look-up table memory 43 may be rewritten.

[0010]

As described above, in the color image frame buffer and the monochrome image frame buffer, the number of image signal systems required for displaying an image and the function of the look-up table memory are provided. Therefore, it was necessary to make it as a completely different device.

[0011] For the display device, the conventional color C
With the RT monitor, even if the convergence accuracy of the electron beam increases,
Due to restrictions on the pixel pitch due to the working accuracy and mechanical strength of the shadow mask and aperture grille, the fineness of the emission point sequence of the three primary colors RGB is not sufficient. Therefore, the color CR
When a monochrome image is displayed on the T monitor, a dot sequence of three primary colors can be perceived, resulting in a great loss of image quality.

As described above, since both the display device and the frame buffer are separately formed for a color image and a monochrome image, a color image such as a pathological image and an X-ray image are separately formed.
It has been difficult to handle monochrome images such as line images in an integrated manner on the same system.

In addition, as long as the image frame buffer and the display device are connected by an analog video interface, any processing such as luminance conversion for monochrome display on the way will immediately lead to deterioration of display image quality.

With respect to cost, full-color image display devices are used in a relatively wide range and are manufactured in large quantities, so mass production is expected to reduce costs. However, applications and quantities of monochrome image display devices are limited. The cost was high.

An object of the present invention is to handle a color image and a monochrome image in an integrated manner, without deteriorating the image quality.
Another object of the present invention is to provide a digital image display device capable of reducing the cost of a monochrome image display device.

[0016]

A digital image display apparatus according to the present invention has three frame memories for storing image data of three primary colors of a color signal RGB, and outputs three systems of 8-bit digital image signals. A color image frame buffer for output, a color liquid crystal display device for inputting and displaying an image signal using a digital video interface,
Means for inputting an 8-bit digital image signal of a system and generating a 16-bit digital image signal by combining the first and second digital image signals of the two systems;
A look-up table memory for converting the 16-bit digital image signal into an 8-bit digital image signal, and the converted 8-bit digital image signal are copied into three to have the same values for R, G, and B. There is provided a color / monochrome image signal conversion circuit including means for inputting the three series of image output data to the color liquid crystal display device and displaying it as a monochrome image.

In the digital image display apparatus of the present invention, a color liquid crystal display device is used, and a color image,
Display both monochrome images. At that time, RGB3
The pixel pitch is made sufficiently small so that each element of the primary colors cannot be visually recognized.

Further, by connecting the color liquid crystal display device and the color image frame buffer via a color / monochrome image signal conversion circuit, the color image frame buffer can be shared with the monochrome image display frame buffer. At this time, a digital interface is used to interconnect the three parts of the color image frame buffer, the color liquid crystal display device, and the color / monochrome image signal conversion circuit to transmit image data.

The color / monochrome image signal conversion circuit converts a 16-bit signal obtained by combining two systems out of three 8-bit color signals into an 8-bit image using a look-up table memory and distributes the signal to the three systems. And output it to a color liquid crystal display device.

At this time, in the color / monochrome image signal conversion circuit, the remaining one input system may be regarded as an overlay image signal and superimposed on the image signal converted by the look-up table memory.

Further, the color / monochrome image signal conversion circuit may have a function of externally switching so that the input signal is output as it is without signal conversion.

[0022]

Next, embodiments of the present invention will be described with reference to the drawings.

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

The digital image display device of this embodiment comprises a color image frame buffer 2, a color / monochrome image signal conversion circuit 3, and a digital input color liquid crystal display device 5.

The color image frame buffer 2 needs to use a digital interface as a video output method. The function of the color image frame buffer 2 is to input image data from a data bus 1 for connecting to a computer and display it as three primary colors of a color signal RGB, as described in the background art. Three 8-bit frame memories 11, 12, 1
3 is to store image data and output a digital video signal.

In the case of displaying a monochrome image according to the present embodiment, conventionally, three color plane frame memories assigned to the three primary colors of RGB are used as frame memories having different functions. Three frame memories into a first frame memory 11,
The second frame memory 12 and the third frame memory 13 will be described.

The image data stored in the first frame memory 11, the second frame memory 12, and the third frame memory 13 are sequentially scanned and read out, multiplexed by the digital video signal output circuit 15, and multiplexed by the digital video signal output circuit 15. Is output. In the case of displaying a color image, the video signal output may be directly input to the color liquid crystal display device 5 corresponding to the digital input. The color image frame buffer 2 may have an overlay plane function.
In the case where the signal of the color image frame buffer 2 is input to the color liquid crystal display device 5 to display a color image without passing through the monochrome image signal conversion circuit 3, the circuit configuration is the same as that of the conventional configuration illustrated in FIG. be equivalent to. In the present embodiment, when displaying a monochrome image, the overlay function built in the color image frame buffer 2 is not used.

When displaying a monochrome image,
Two of the three frame memories 11, 12, and 13 of the color image frame buffer 2 are used for storing image data. Generally, a monochrome image having a resolution exceeding 8 bits is represented using two bytes per pixel. At least 10 bits are required for a 1024 gradation image, and 12 bits are required for a 4096 gradation image. For data handling and storage in a computer, it is customary to use 2 bytes in byte units. In the present embodiment, of the monochrome image data represented by the two bytes, the upper one byte is stored in the first frame memory 11 and the lower one byte (8 bits) is written in the second frame memory 12.

The output signal of the color image frame buffer 2 is input to a color / monochrome image signal conversion circuit 3, and the digital video signal input circuit 16 of the first stage again outputs three systems of an 8-bit digital image signal and a vertical synchronizing signal.
Decomposed into horizontal synchronization signals. Of these, the image signal from the first frame memory 11 and the image signal from the second frame memory 12 are input to the look-up table memory 17. In the look-up table memory 17, as shown in FIG. 2, two 8-bit signals are arranged into a 16-bit width signal, and the 8-bit data is output by referring to the contents of the look-up table memory 17 using this signal as an address. And In FIG. 2, a lookup table memory 1
7 are stored in the data bus 1 and LU in the same manner as the image data.
The data is written through the T update circuit 18 to form a conversion table from 16-bit data to 8-bit data. By rewriting the contents of the look-up table memory 17 even while an image is being displayed, it is possible to change the brightness of the image being displayed or to reverse the brightness of the image.

The image data output from the look-up table memory 17 is copied into three, and is converted into three series of image output data having the same values for R, G and B. Are multiplexed together and input to the color liquid crystal display device 5 and displayed as a monochrome image.

In order to display an overlay image such as a pointer in a monochrome image, an overlay operation circuit 20 is added as shown in FIG.
3 is superimposed on the image signal from the look-up table memory 17. That is, when the signal value of each pixel of the overlay plane is zero, the signal value of the look-up table memory 17 is preferentially output, and if there is a non-zero value on the overlay plane side, this is preferentially output. I do.

When displaying a medical image on a color image liquid crystal display, the frame memories 11, 12, and 13 of the color image frame buffer 2 require a display resolution of about 2000 pixels × 2000 pixels as a display area. Accordingly, the storage capacity of each memory portion of the color image frame buffer 2 requires a capacity of 4 Mbytes for each color plane.

On the other hand, when displaying a monochrome image on the color liquid crystal display device 5, if the pixel spacing is coarse, 3
Each light emitting cell of the primary color can be visually perceived, thereby deteriorating the image quality. Empirically, if the pixel pitch is set to 115 pixels or more per inch, there is no problem of perceiving cells of three primary colors. Displaying at 115 pixels per inch on the color liquid crystal display device 5 results in a square of 45 cm,
It is the same size as seen on film.

In the digital image display device according to the present embodiment, a color image can be displayed by directly connecting the color image frame buffer 2 and the color liquid crystal display device 5, and a color / monochrome image signal conversion circuit 3 is provided between the two. , The display of a high-gradation monochrome image becomes possible. In order to use a common circuit for these two displays, as shown in FIG.
The video signal and the output of the color image frame buffer 2 are input to a monochrome image signal conversion circuit 3, selected by a video signal selection circuit 4 that can be controlled from a data bus 1, and connected to a color liquid crystal display device 5.

[0035]

As described above, the present invention has the following effects. 1) Claim 1 In the color liquid crystal display device, the display pixel density can be increased beyond the limits of the electron beam diameter and the pixel pitch of the shadow mask / aperture grille, which are problems in the color CRT, and the visual density can be increased. This makes it difficult to distinguish pixel dots, and enables high-quality display on a color display device without pixel dot stripes deteriorating image quality. By setting the pixel pitch to 115 dots / inch or more, RG, which is a basic element of a pixel even when approaching considerably,
Monochrome display can be performed without visually recognizing the dot sequence of the B3 primary color.

The color / monochrome image signal conversion circuit can use a combination of a color frame buffer and a display device for monochrome image display and color image display, and can share the device. Costs can be reduced.

At the time of displaying a monochrome image, by rewriting the look-up table memory in the color / monochrome image signal conversion circuit, high-speed image brightness and contrast conversion can be performed in the same manner as a conventional monochrome image frame buffer. It is.

Further, since the connection of the liquid crystal display device, the color image frame buffer, and the color / monochrome image signal conversion circuit is a digital signal, image deterioration can be prevented even when the color / monochrome image signal conversion circuit is used. 2) The color / monochrome image signal conversion circuit can be switched by an external control signal so that the original input signal is output, so that the circuit does not have to be physically attached or detached. The display device can be used for both color and monochrome. 3) Claim 3 The image signal of the third frame memory can be used as a frame memory for pointer display.

[Brief description of the drawings]

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

FIG. 2 shows a 16-bit /
FIG. 7 is an explanatory diagram of 8-bit image conversion.

FIG. 3 is a configuration diagram of a digital image display device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a digital image display device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional color image display device using a digital video interface.

FIG. 6 is a configuration diagram of a conventional monochrome image display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Data bus 2 Color image frame buffer 3 Color / monochrome image signal conversion circuit 4 Video signal selection circuit 5 Digital input color liquid crystal display device 6 Digital video signal output circuit 7 Color display monitor 8 Monochrome image frame buffer 9 Monochrome CRT monitor 11 First Frame memory 12 Second frame memory 13 Third frame memory 14 Synchronous signal generator 15 Digital video signal output circuit 16 Digital video signal input circuit 17 Look-up table memory (LUT) 18 LUT update circuit 19 Digital video signal output circuit 20 Overlay operation Circuit 21 Frame memory for red signal 22 Frame memory for green signal 23 Frame memory for blue signal 24 Frame memory for overlay 25 to 27 Look-up table Rumemori (LUT) 28 sync generator 29-31 overlay calculation circuit 32 the digital video signal output circuit 41 frame memory 43 for monochrome frame memory 42 overlay LUT 45 D / A converter 46 synchronizing signal generator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 5/36 510 H04N 7/18 L H04N 7/18 9/64 H 9/64 G09G 5/00 520W F Term (reference) 5C006 AA22 AF06 AF23 BB11 BC16 BF02 FA03 5C054 AA01 CA02 DA01 DA09 EA05 EB07 ED17 EE08 EH07 EJ05 EJ07 FA02 FB01 FB03 FD00 FE05 FF03 GA04 GB15 GC04 HA12 5C066 AA11 CC13 DD0613 KK26 5C082 AA04 BA20 BA34 BA35 BA36 BA39 BB01 BB16 BB51 BD02 CA84 CB01 CB06 DA51 MM06 MM07 MM10

Claims (3)

[Claims] 1. A system comprising three frame memories for storing image data of three primary colors of a color signal RGB and three systems of 8
A color image frame buffer for outputting a digital image signal of 4 bits, a color liquid crystal display device for inputting and displaying an image signal using a digital video interface, and three 8-bit digital signals output from the color image frame buffer An image signal is input, and the first and second digital image signals of these two systems are combined and
Means for generating a 6-bit digital image signal, a look-up table memory for converting the 16-bit digital image signal into an 8-bit digital image signal,
The converted 8-bit digital image signal is copied into three to form three-series image output data having the same values of R, G, and B, and is input to the color liquid crystal display device to be displayed as a monochrome image. A digital image display device having a color / monochrome image signal conversion circuit including means. 2. A system comprising three frame memories for storing image data of three primary colors of a color signal RGB, and three systems of 8
A color image frame buffer for outputting a digital image signal of 4 bits, a color liquid crystal display device for inputting and displaying an image signal using a digital video interface, and three 8-bit digital signals output from the color image frame buffer An image signal is input, and the first and second digital image signals of these two systems are combined and
Means for generating a 6-bit digital image signal, a look-up table memory for converting the 16-bit digital image signal into an 8-bit digital image signal,
A color / monochrome image signal conversion circuit including means for copying the converted 8-bit digital image signal into three and outputting as three series of image output data having the same values for R, G, and B; A digital image display device having a video signal selection circuit for outputting an output signal of the color image frame buffer or an output signal of the color / monochrome image signal conversion circuit to the color liquid crystal display device according to a monochrome display switching signal. 3. The color / monochrome image signal conversion circuit according to claim 1, wherein the color / monochrome image signal conversion circuit obtains the 8
The third input digital image signal
3. The apparatus according to claim 1, further comprising means for superimposing and outputting an 8-bit digital signal of said system.