JPH04342291A - Picture display device - Google Patents

Abstract

PURPOSE:To omit hardware for display of only natural pictures by displaying a natural picture having a large data volume together on a display means on which map data and guide information data are displayed. CONSTITUTION:The natural picture digital signal which is digitized and compressed and is recorded on a recording medium is read out by a read means (CD-ROM drive) 6 and is decoded by soft operation of an operation control means (ROM) 3. The natural picture is drawn and displayed on a display device by a display means (video RAM) 10 in the same manner as graphic drawing after bit reduction. Since the compressed natural picture digital signal is decoded and the bit processing is performed by arithmetic processing based on software in this case, hardware like a decoder only for natural picture is omitted, and the cost is reduced and the device is miniaturized.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Field of Industrial Application] The present invention relates to an image display device suitable for use in a car navigation system, and particularly relates to an image display device suitable for use in a car navigation system.
- Read out natural image (gravure photograph) data together with map data and guide information data recorded in a ROM, etc., and provide the data to an image display device that displays the data on a display.

0003

[Prior Art] Generally, a car navigation system is equipped with an image display device in a car, but this is a CD-ROM.
Map data and guide information data recorded in a data recording medium such as a ROM are read out, a graphic image is created by temporarily drawing it on a video RAM based on this data, and this is displayed on a display.

Map data and guide information data are recorded in a format such as vector data, and character data is recorded as code data such as Shift JIS. In order to draw this, a display display means consisting of a graphic controller, video RAM, memory controller, and color palette is provided. With this display means, in order to make the hardware more compact and lower in price,
The number of dots per pixel is limited, for example, 4 dots per pixel. In this case, if you display it in color, 16 (2
4) Color is the limit.

By the way, as a recent image display device, C
Along with map data and guide information, natural pictures (
A device that can record gravure photo data and display natural images in addition to graphic images has been proposed.

This image display device divides one pixel of natural image data into three primary colors, R, G, and B (red, green, and blue), and quantizes each of them with 8 bits. However, if this continues, the amount of data will be enormous, so the signal will be compressed and stored on a CD-ROM.
to be recorded. As an example of the compression method, for example, 1/3
Some use delta YUV coding to perform compression. This converts RGB signals into luminance signal Y and color difference signal U.
, V, and the difference value between the previous pixel signal and the next pixel signal is used as a coding signal for each pixel based on one scanning line. Therefore, the recording signal to the CD-ROM is the initial value Y0, U0 corresponding to the left end of one line.
, V0, and the difference values ΔY, ΔU, and ΔV for each pixel compressed to 4 bits. In order to reproduce this signal and restore the image, it is sufficient to convert ΔY, ΔU, and ΔV to YUV, further convert to RGB 8-dot data, and display this on a display.

[0007]

[Problem to be Solved by the Invention] In such a conventional image display device, the signal-compressed natural image data Δ
Converting the Y, ΔU, and ΔV signals to 8 bits each for RGB and displaying these 8-bit signals on a display requires hardware such as a decoder for signal expansion conversion and three DA converters.

In other words, in the conventional image display device, one pixel is 4
Since the number of bits per pixel is limited, displaying natural images requires hardware such as the decoder mentioned above, making image display devices more complex, larger, and more expensive. I will invite you.

Furthermore, it is necessary to add a system program to control this hardware on the map display computer side and to match it with the conventional map display, resulting in a significant change in the operating software.

[0010] The present invention was made in consideration of these circumstances, and its purpose is to process natural images with a large amount of data.
An object of the present invention is to provide an image display device that can omit hardware dedicated to displaying natural images by simultaneously displaying map data and guide information data using a display means. [Structure of the invention]

[0011]

[Means for Solving the Problems] In order to solve the above problems, the present invention is constructed as follows.

The invention according to claim 1 of the present application (hereinafter referred to as the first invention) is to digitize and compress natural image data to obtain a natural image digital signal, together with digitized map data and guide information data. a recording medium for recording, a means for reading the digital signal of the natural image, the map, and the guide information from the recording medium; a display means for graphically displaying the map data and the guide information data read by the reading means on a display; The apparatus is characterized by comprising arithmetic control means for restoring the natural image digital signal read by the reading means to a pre-compression signal through arithmetic processing and displaying the natural image on the display means.

[0013] In the invention according to claim 2 of the present application (hereinafter referred to as the second invention), the arithmetic control means reads only luminance information from the natural image digital signal and displays the natural image in black and white on the display of the display means. It is characterized by having the following.

In the invention according to claim 3 of the present application (hereinafter referred to as the third invention), the arithmetic control means reads the three primary color data from the natural image digital signal, reduces bits, and displays the natural image in color on the display of the display means. It is characterized by having means for displaying.

[0015]

[Operation] <First invention> A natural image digital signal digitized and compressed and recorded on a recording medium is read out by a readout means, and further decoded by soft calculation processing of an arithmetic control means, Further, the bits are reduced and the image is drawn and displayed on the display by the display means in the same manner as graphic drawing.

Therefore, according to the present invention, since decoding and bit processing of a compressed natural image digital signal are performed by arithmetic processing based on software, hardware such as a decoder dedicated to natural images can be omitted, and costs can be reduced. It is possible to achieve both reduction and miniaturization of the device.

[Second invention] Only the luminance information in the natural image data is extracted by the calculation control means of the first invention and displayed in monochrome on the display as a natural image. In other words, according to the present invention, a natural image can be displayed in monochrome without separately providing dedicated hardware for displaying a natural image in monochrome.

<Third invention> RGB3 in natural image data
The primary color data is read out by the arithmetic control means of the first invention and displayed in color on the display as a natural image. That is, according to the present invention, natural images can be displayed in color without separately providing dedicated hardware for displaying natural images in color.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the overall structure of an embodiment of the first invention of the present application. This system graphically displays the vehicle's location, guide information, etc. on a map or natural image, overlaying it on a display.

The image display device 1 includes a CPU 2 as an arithmetic and control unit that controls the operation of the entire device, and a ROM that stores programs and data via a bus line.
3 and RAM4 are connected. The ROM 3 stores programs such as procedures for displaying maps and guidance information, arithmetic processing for displaying natural images, and input control methods for switches and the like for instructing operations.

[0022] Furthermore, the CPU 2 performs I/O via the bus line.
A CD-ROM drive 6 is connected via the controller 5, and the CD-ROM drive 6 reads the CD-ROM.
The data recorded in 7 is read out. That is, the CD-ROM 7 records map data, guide information data, and natural image data, and these data are read out by the CD-ROM drive 6 and provided to the CPU 2 from the I/O controller 5. DM
A8 is provided to perform data transfer quickly and efficiently. The data read under the control of the CPU 2 is given to the video RAM 10 via the display controller 9, where it is drawn as an image. This drawing is 1
The pixel is developed as 4 bits (Y, R, G, B). The colors determined by these 4 bits, that is, 16 colors, are preset as a data table on the color palette 11, and according to the 4-bit input, DA-converted RGB signals are supplied to the display 12, and the image is displayed in color. .

The display controller 9 is a central element of the drawing section, and is connected to a video RAM 10 and a color palette 11 via a memory control/parallel/serial conversion section 13, as shown in FIG.

[0024]The display controller 9
Drawing such as line drawing and filling according to commands from PU2,
Controls character drawing, screen scrolling, etc. The processed data is given to the memory control/parallel/serial converter 13 and developed on the video RAM 10 as graphic data. The video RAM 10 can form images each of Y, R, G, and B so that each pixel corresponds to 4 dots, and can have a parallel configuration of 4 memories. The data on the video RAM 10 is converted into Y, R, G, and B serial data by a memory control/parallel/serial converter 13 and provided to the color palette 11. The color palette 11 is set in advance with 16 color data, the number of colors determined by 4 bits, and input Y, R,
The color palette data corresponding to the addresses represented by G and B is read out, DA converted, and an analog signal is taken out. Also, from the display controller 9, horizontal,
Since vertical synchronization signals HS and VS are generated, these signals R, G, B, HS, and VS are applied to the display 12 to display an image in color.

3 to 5 show flowcharts of the arithmetic processing stored in the ROM 3 of the arithmetic control means for displaying the natural image data recorded on the CD-ROM 7 on the display, and FIG. 12 is a decoding flowchart of conversion.

The CD-ROM 7 employs the delta YUV system as a system for compressing and recording natural image data. In other words, the RGB image signals are 8-bit quantized, and the luminance signal Y and color difference signals U(B-Y) and V
(RY), and the difference values ΔY, ΔU, and ΔV between the preceding and succeeding pixels are compressed into 4 bits in units of one line to record a natural image.

The above inverse transformation is performed on the reproduction side. This is the program flowchart shown in FIGS. 3 and 4. First, in P1, ΔUn, ΔYn, ΔVn, ΔYn+1 are read from the CD-ROM 7 in the order, and this read set 2
The serial data string D1 of bytes is rearranged in words at P2 as follows, and regrouped into each set of ΔY, ΔU, and ΔV.

[0028] Y0, ΔY1, ΔY2,... ΔY359U
0, ΔU1, ΔU2,... ΔU179V0
, ΔV1 , ΔV2 ,... ΔV179 However,
Each subscript number of Y, U, V indicates a pixel, and the total number of pixels is 36
It is 0.

Then, in P3, delta YUV-YUV conversion is performed. At this time, the 4-bit data is redeveloped into 8-bit data according to the conversion rules as shown below, and 1 of the scanning lines is
The pixel data is the sum of the data before the pixel and the difference value data.

[0030]

[Math 1]

[0031] However, C0 to Cn are ΔY, ΔU, ΔV
, and C0 indicates its initial value. Since the U and V data are recorded in the form of thinning out every other pixel, UV interpolation is performed at P4 as shown below.

[0032] Interpolate with U1'=(U1+U2)/2...V1'=(V1+V2)/2...Furthermore, P5
Then, convert to an RGB signal using the following RGB conversion formula.

R=Y+1.371*(V-128)G=
Y-0.336*(U-128)-0.698*(V-
128) B=Y+1.732*(U-128) Finally, P so that the R, G, B data is within 8 bits.
Clip at 6.

This series of processing is performed on the CPU 2 according to the program written in the ROM 3, and
Accumulate data in.

Next, FIG. 4 shows a program for displaying a natural image in black and white on the display 12 using this data.
The explanation will be based on the flowchart.

In this case, the 8-bit luminance signal Y data obtained at P3 in FIG. 3 is taken out, and the brightness distribution within one pixel is determined. The range in which this brightness frequency exceeds a certain value is P
11, and the bit division range is selected from the distribution of the luminance signal Y frequency. This range is represented by 4 bits and 16 gradations by bit reduction of P12. For example, set the range of brightness 0 and 1 to 1
When dividing into 6 bits, the upper 4 bits of the 8 bits are used as data.

Next, in P13, the color palette is set to RGB values corresponding to 16 gradations. P this
If the data is converted from analog to digital at step 14 and sent to display 12, a natural image will be displayed in black and white with 16 gradations.

Next, a program for displaying color on the display 12 will be explained based on the flowchart shown in FIG.

This is done by calculating the data frequency within one screen in P21 using the luminance signal Y obtained in P3 of FIG. Extract the range above a certain threshold. This range is divided into 64 gradations if the size of the mask pattern used in the dither processing performed in the next step P22 is, for example, 8×8 pixels. In this dither processing, for example, a dither pattern of 8 x 8 pixels as shown below is stored in the ROM 3 in advance, and a data comparison is made between this dither pattern and the original signal.If the original signal is smaller than the value of the dither pattern, the dither pattern is Binarization is performed in which the value is set to 1 when the value is greater than or equal to the pattern value.

[0040]

[Table 1]

The thus obtained binary data Y, R, G,
B is set as the address for setting the color palette 11 in P23, and values corresponding to each color are registered in the color palette 11. The signal obtained from the color palette 11 is subjected to DA conversion at P24, and the obtained RGB signal is applied to the display 12 to display the natural image in pseudo color. More than P
The processes from 21 to P23 are performed by software calculation processing by the CPU 2 based on the program written in the ROM 3.

Although dither processing was performed in this embodiment, instead of performing dither processing, each of the 8-bit data of Y, R, G, and B is binarized in size based on a certain threshold value, for example, 128, and a pseudo It can also be displayed in color.

[0043] Furthermore, the software calculation process also applies to bit reduction (P12) and color palette settings (P13, P23) when the number of colors that can be set simultaneously on the color palette 11 increases, for example when displaying 256 colors. This can be done by simply changing the part. In this case, the number of gradations and colors increases, further improving the image quality.

[0044]

Effects of the Invention As explained above, the first to third inventions of the present application restore the compressed natural image digital signal to the pre-compression signal through software arithmetic processing. It is possible to display in pseudo color or black and white without making any changes or additions to dedicated hardware. Therefore, even if the natural image data storage method and coding method are different, it can be easily handled by simply changing the software.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of an image display device according to first to third inventions of the present application.

FIG. 2 is a diagram showing the configuration around the display controller shown in FIG. 1.

FIG. 3 is a flowchart showing a decoder program for compression and inverse conversion (expansion) of the arithmetic method control device shown in FIG. 1;

FIG. 4 is a flowchart showing an example of a program according to an embodiment of the second invention of the present application.

FIG. 5 is a flowchart showing an example of a program according to an embodiment of the third invention of the present application.

[Explanation of symbols]

1 Image display device 2 CPU 3 ROM 4 RAM 6 CD-ROM drive 7 CD-ROM 9 Display controller 10 Video RAM 11 Color palette 12 Display

Claims (3)

[Claims] 1. A recording medium for recording a natural image digital signal obtained by digitizing and compressing natural image data together with digitized map data and guide information data; means for reading out a guide information digital signal; display means for graphically displaying the map data and guide information data read by the reading means on a display;
An image display device comprising: arithmetic control means for restoring the natural image digital signal read by the reading means to a pre-compressed signal through arithmetic processing, and displaying the natural image on the display means. 2. The image display device according to claim 1, wherein the arithmetic control means includes means for reading only luminance information from the natural image digital signal and displaying the natural image in black and white on the display of the display means. 3. The arithmetic control means has means for reading three primary color data from the natural image digital signal, reducing bits, and displaying the natural image in color on the display of the display means. Image display device.