JPH0319584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates to a decoding device for encoded image information used in a system for searching and displaying image information stored in a center or the like.

(2) Description of the prior art In systems that search and display image information stored in a center, etc., the resolution of the display device is limited, so screen information (original screen information and all of the
It is not possible to display them simultaneously on a display device with sufficient resolution. For this reason, in the conventional technology, the information is divided into a plurality of small screen information having the number of pixels according to the resolution of the display device, a unique name such as a screen number is given to each small screen information, and this is used as a keyword to select. In order to search and display divided small screen information as a unit, each small screen information was encoded and stored, and then decoded and displayed at the center or terminal when provided.

In this way, in the conventional technology, decoding and display are performed using small screen information divided in advance as a unit, so it is possible to display image information at any position other than the divided unit, or to change the positional relationship between adjacent small screen information, etc. If it is necessary to confirm the information, use methods such as creating overlapping parts between adjacent small screens, or composing a small screen information code at an intermediate position from multiple adjacent small screen information codes each time it is displayed. was. However, these methods have drawbacks such as an enormous amount of code to be stored or a significant increase in the amount of processing such as extraction and compositing. Furthermore, when a search is repeated, it is necessary to transmit all the codes constituting the small screen information to the display device each time, resulting in a delay in response and display time.

(3) Purpose of the Invention The purpose of the present invention is, in order to solve the above-mentioned drawbacks, to improve the resolution of the display device without dividing the original screen information, which is a continuous piece of information such as an aerial photograph, into small screen information. From a general image that roughly represents the original screen information with a sufficient number of pixels to display, to a detailed image that represents the original screen information in detail with the same number of pixels as the original screen information, the resolution is layered into several layers and the difference information between each layer is created. An object of the present invention is to provide an image information decoding device that decodes image information encoded using a simple device and process, thereby shortening the time required to search for original screen information.

(4) Explanation of structure and operation of the invention The present invention will be explained in detail with reference to embodiments. In doing so, the codes to be decoded by the image information decoding device according to the present invention will be explained below. do. FIG. 2 schematically represents the hierarchical structure of an image. The code to be decoded by the image information decoding device according to the present invention is, in image information composed of a matrix type pixel set, the pixel set is divided into 2 ⁿ × 2 ^m pieces (n, m are positive integers). By dividing the pixel into a set of pixels (hereinafter referred to as a block) and encoding using the average value of the pixel values (luminance signal or density signal value) of the pixels belonging to the block, the code of the basic layer (hereinafter simply referred to as the basic (called a code),
Next, each of the above blocks is further divided into 2 ⁿⁱ × 2 ^mj (n _i , m _j
is a positive integer), and encodes it using the difference between the average value of the pixel values in that subblock and the average value of the block to which this subblock belongs. The sub-blocks are regarded as blocks, and the encoding is repeated for even smaller sub-blocks, thus forming a hierarchical structure. FIG. 2 shows an example in which the number of layers is three. The third layer consists of the average value of a 4×4 pixel block of original screen information, and this average value is encoded as a basic code. The second layer consists of the average value of a 2×2 pixel block of original screen information, and the difference between the average value and the corresponding average value of the third layer block is encoded as a difference code. The first layer consists of the average value of a block of 1 (1 x 1) pixel of the original screen information, and the difference between this average value and the corresponding average value of the second layer block is encoded as a difference code. do.

FIG. 1 shows an embodiment of the present invention, in which 11 is a center processing device, 12 is an interface device, 13 is a transmission line, 14 is a terminal device, 15 is a decoding device according to the present invention, 16 is a display device, 17 is an indicating device.

The center processing device 11 stores encoded image information, and receives the layer identifier indicating the number of the next layer to be displayed from the instruction device 17 and the key address indicating the start coordinates and width of the specified partial area. The stored code corresponding to the partial area is read out in accordance with the signal and sent to the terminal device 14 through the interface device 12 and transmission line 13. Within the terminal device 14, the sent code is transferred to the interface device 12.
The data is sent to the decoding device 15 via the . Decoding device 15
As will be described later, image information for one screen of the display device 16 is decoded, and the display device 16 displays this. Here, if the terminal user uses the instruction device 17 to specify a partial area within the display screen, the instruction device 1
7 generates a layer identifier and a key address signal for the next layer to be displayed, prompts the center processing device 11 to send the code and the decoding device 15 to decode, and the above-described decoding and display is repeated.

FIG. 3 is a block diagram showing the configuration of the decoding device 15, in which 21 is an arithmetic unit, 22 is a code memory, and 2
3 is a control unit, and 24 is a frame buffer.

FIG. 4 is a schematic representation of the encoded image and decoded image input and output in the decoding device 15. Among the large rectangular frames, A indicates the display range of the display device 16, and B indicates the instruction. The range indicated using the device 17 is shown. Further, small rectangles arranged in a matrix indicate each pixel, and the numerical value indicates the code value at each pixel.

Taking the encoded image shown in Fig. 2 as an example, the third
The operation of the decoding device will be explained in detail with reference to FIGS. The code memory 22 consists of two memories 22-1 and 22-2 that operate independently, one of which is in a writing state (writing side) and the other in a reading state (reading side). Both states are switched each time decoding is completed. In the initial state, the reading side memory is cleared to 0. At the beginning of the decoding operation, the instruction device 1
7 to the center processing unit 11, the code of the third layer, which is the basic code, is sequentially input to the calculation unit 21. The layer identifier and key address signal are also input to the control unit 23,
The control unit 23 temporarily stores these. Control unit 23
controls the read-side memory, and its contents are input to the arithmetic unit, but since the value is 0, the basic code is stored as is in the write-side memory as shown in Figure 4-()A, and is decoded. It is stored in the frame buffer 24 as image information. Display device 1
6 reads the contents of the frame buffer 24,
Display the third layer image. When a partial area within the display image is specified by the instruction device 17 as a detailed image area to be displayed next, the next decoding is started. The instruction device 17 inputs the layer identifier and key address signal of the detailed image to be displayed next to the center processing device 11 and the control unit 23. Here, the reading side and the writing side of the code memory 22 are switched, and if the designated area is B in FIG. The signals are sequentially input to the arithmetic unit 21 together with the differential code sent in the image of FIG. 4-()A and are synthesized. At this time, the control unit 23 compares the value of the layer identifier temporarily stored immediately before with the value of the newly input layer identifier. If the differential code is from a layer adjacent to the layer decoded immediately before (the second layer in this case), then for one pixel in Figure 4-()B, Figure 4-()A The four pixels of
The control unit 23 controls the read-out side memory, and as the four pixels of numerical values 1, 2, 3, and 1 in FIG.
By repeatedly reading out one pixel with the numerical value 10 in Figure-()B four times and inputting it to the arithmetic unit 21,
() Combine the image information of the layer with the image of A.
Decrypt. The control unit 23 temporarily stores the newly input layer identifier and key address signal in addition to those previously stored temporarily.

The decoded image information that has been synthesized and decoded is stored in the frame buffer 24 and also in the write side of the code memory 22, and is used for decoding the next layer.

In this way, decoding is basically repeated between adjacent layers one after another, but the currently displayed image information and the differential code of a layer two or more layers away from the image layer are combined and decoded. It is also possible to display the For example, in the above explanation, if the first layer differential code is sent instead of the second layer differential code, the control unit 23 compares the temporarily stored layer identifier with the input layer identifier, and then This is detected and the readout control is changed so that 1 pixel in FIG. 4-()B corresponds to 16 pixels in FIG. 4-()A. The number of images P to be associated is determined by P=4 ^S , where S is the difference between the number of layers of the currently displayed image and the number of layers of the image to be displayed next.

In this way, images of layers two or more layers apart that are decoded and displayed are synthesized with the difference codes of intermediate layers missing, so compared to the original detailed images that are synthesized without missing them, Although there is a risk that the quality of the image may deteriorate, since the difference codes of intermediate layers are not transmitted from the center processing device 11, the time required for display is shortened. This image is called an approximate image.

The arithmetic unit 21 is constituted by an adder that outputs the sum of two inputs, and by providing as many adders as the number of pixels in a block, it is possible to process a plurality of pixels simultaneously. Control unit 23 is fully configurable using conventional logic circuit technology. Further, the calculation section 21 and the control section 23 can also be realized by a general-purpose microprocessor and a control program according to conventional technology. The code memory 22 includes a pair of RAMs each having a capacity at least equal to the code amount of the basic code, and a selection circuit that switches read/write signals and address signals to place one of the pair of RAMs in a read state and the other in a write state. Consisting of: The frame buffer 24 is constituted by a RAM having a capacity equivalent to one screen of the display device 1.

In the above explanation, the decoding device has been described as a decoding device for monochrome multivalued image information, but the decoding device is not limited to this, and as shown in FIG. ·green·
Regarding color image information divided into blue color components, for example, the red component is first decoded and temporarily stored in the frame buffer 24, and then the green component is decoded and combined with the red component in the frame buffer 24. Finally, the blue component is decoded, and 3
It is possible to synthesize the components, and it is also possible to synthesize Y・I・
The Q signal components can also be decoded and combined in the same manner, and encoded color image information can also be decoded.

In addition, when compression encoding is performed during encoding, a preprocessing unit 26 is added before the decoding device 15 as shown in FIG. 6, and by decoding the compression code in advance, the layer It is also possible to decode encoded compression codes.

In the above explanation, the decoding device is used for encoded image information representing a wide area such as an aerial photograph, but the small screen information handles image information that constitutes a wide area by a collection of independent information that has no relationship with each other. It is also possible.

(5) Explanation of Effects As explained above, the image information decoding device according to the present invention converts image information that is hierarchically encoded as a piece of information from a general image code to a detailed image code into a general image or the detailed image code. Any part of the image can be decoded to be displayed as a detailed image on the entire screen of the display device. Furthermore, detailed information is decoded one after another by combining the previously decoded information and the difference information.
The amount of transmitted codes can be reduced. In particular, in the present invention, instead of sequentially decoding layers,
For example, by adding and decoding the difference value from the average value within a 2x2 pixel subblock of a 1x1 pixel subblock within the block to the average value within a block of 4x4 pixels, By combining and decoding the value and the difference value in a layer two or more layers away from the relevant layer, an approximate image of the detailed image can be decoded and displayed at high speed, and the correctness of the search can be determined using the approximate image. The required time can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a schematic diagram of the hierarchical structure of an image, Fig. 3 is a block diagram of an embodiment of a decoding device, and Fig. 4 is a diagram showing the decoding of image information pixel by pixel. FIG. 5 is a block diagram of another embodiment of the decoding device, and FIG. 6 is a block diagram of another embodiment of the decoding device. 11... Center processing device, 12... Interface device, 13... Transmission line, 14... Terminal device,
15...Decoding device, 16...Display device, 17...
. . . instruction device, 21 . . . arithmetic section, 22 . . . code memory, 23 .

Claims (1)

[Claims] 1. Image information encoded using the most schematic image information and difference information between each layer so that the image becomes hierarchically more detailed from the general image to the detailed image. A decoding device that includes a code memory that stores the sent general image information or the information decoded immediately before, and an arbitrary designated area portion of the general image information stored in the code memory or the information decoded immediately before. An arithmetic unit capable of synthesizing information extracted from an arbitrary specified area of information and difference information of a layer two or more layers away from the extracted portion; In addition to controlling reading from the code memory, it also controls calculations by the calculation unit, decodes detailed images that are two or more layers away from the general image information or the information decoded immediately before, and controls writing to the code memory. An image information decoding device comprising: a control section that controls output of decoded information. 2 The encoded image information is separated into red, green, and blue color components or Y, I, and Q signal components, and each component is hierarchically encoded based on the difference value between each layer. 2. The image information decoding apparatus according to claim 1, wherein the control unit is configured to control decoding for each of the components.