JP3062507B2 - Image encoding device and image decoding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital image processing, and more particularly, to an image compression system for encoding image data.

<Conventional technology> As a means for combining and displaying multiple image data at conferences and lectures, various video display devices such as large projectors have been widely used in place of conventional OHP and slide projectors. Have begun to do. Unlike conventional devices, these video display devices are based on electronic means supported by the cost reduction of semiconductor devices such as memories, and use a personal computer to create a composite image for display from multiple image data. And displaying the image on a large screen.

Conventionally, as a method of combining and displaying a plurality of image data using a personal computer or the like, a color photograph, word processing output, etc. are digitized by a camera or a scanner and taken into a memory or the like, and the image data is enlarged, reduced, cut out, and layout processed. And other editing operations to create an image for display. The display image created in this way is recorded on a recording medium such as a magnetic disk or a floppy disk, and is carried to a conference hall or a lecture hall to perform a composite display.

<Problem to be Solved by the Invention> In the system for synthesizing and displaying a plurality of image data as described above, since the image data itself is handled, there is a problem that the data amount is large. In particular, it is desirable to use a compact recording medium when bringing the created image to a meeting or a lecture. For this purpose, it is better to use a small amount of data for the same image data. For this reason, conventionally, in a region where the spatial frequency is high, the human eye is relatively insensitive, so that a full-color image is compressed to reduce the data amount.

However, in such an application, as shown in FIG. 6 (a), when a full-color image 61 is set as a background, an appropriate partial image 62 is laid out, and characters 63 for explanation are superimposed and displayed. There is. When a full-color image on which such a character graphic image is superimposed is compressed by a compression method that utilizes the insensitivity of the human eye in the high spatial frequency region as described above, the character / graphic portion may be reduced to obtain a normal compression ratio. However, there is a problem that the compression ratio must be lowered if the deterioration of the character / graphic portion is to be reduced. In the case of a meeting or a lecture, there is a method of changing a part of an image to enhance a display effect. FIG. 6 (b),
In (c), the position of the chair 64 is changed and displayed with the same room as the background. In this way, when the same partial image is displayed in a different position with respect to the same background image,
In the case where the same background image is displayed while replacing a number of character graphic images or partial images, in the conventional technology, it is necessary to separately store a number of partially changed images on a recording medium. Therefore, there was a problem that the data amount had to be increased.

Therefore, an object of the present invention is to synthesize a plurality of pieces of image data capable of obtaining a high compression ratio without deteriorating the image quality and greatly reducing the data amount.

<Means for Solving the Problems> In order to achieve the above-described object, according to the present invention, an image for combining and displaying a desired image with an entire image and one or more partial images having an arbitrary shape is provided. An encoding device, comprising: an image extracting unit that cuts out the partial image from an input image; a position input unit that arbitrarily specifies a synthesis position of the partial images; and an image extracting unit that extracts each partial image based on the specification by the position input unit. Position data determining means for determining position data indicating the synthesis position; area shape coding means for compressing and coding data indicating the shape of the area of the partial image; image information inside the area of the entire image and the partial image Is divided into rectangular blocks of a predetermined size, and image information encoding means for performing compression encoding in block units, the compression-encoded image information and the area shape encoded data, And storage means for storing the position data, wherein the image information encoding means, in the partial image, compression-encodes only blocks containing data in the area of the partial image,
The compression-encoded data has an identifier, and the identifier indicates whether the image information is a rectangular whole image without shape information or an arbitrary-shaped component image with shape information. This solves the above problem.

In addition, as data indicating the shape of the region of the partial image, the value of L bits (L is a natural number) representing a mixture ratio of the image of the region and the image outside the region is used for each pixel, Solve the problem.

In addition, as data indicating the shape of the area of the partial image, an L-bit (L is a natural number) value is used for each pixel, and the first value in the data indicates that the image of the area is displayed as it is. The second value indicates a portion where the image outside the region is displayed as it is, and the other values indicate the portion where the image of the region and the image outside the region are superimposed. The above problem is solved by using a value representing a mixture ratio of the image outside the region and the image outside the region.

Further, an image for decoding encoded data of a combined image obtained by combining the whole image and one or more partial images having an arbitrary shape, and generating a combined image based on position data indicating a combination position of the partial image The decoding device, wherein the image information of the compression-encoded coded data is a rectangular whole image having no shape information or a partial image having an identifier indicating whether it is a partial image of an arbitrary shape having shape information. A partial image determining means for determining whether or not, image information decoding means for decoding the encoded data of the whole image or partial image compression-encoded in rectangular block units of a predetermined size in the block unit, A region shape decoding unit that decodes region shape encoded data when the determination unit determines that the image is a partial image; and a synthesis of the partial image arbitrarily specified at the time of encoding. A position data obtaining means for obtaining location,
Using the data indicating the decoded shape, from the decoded partial image, only data in the area of the partial image,
The above object is attained by providing a synthesizing means for arranging and synthesizing based on the position data.

In addition, as data indicating the shape of the region of the partial image, the value of L bits (L is a natural number) representing a mixture ratio of the image of the region and the image outside the region is used for each pixel, Solve the problem.

In addition, as data indicating the shape of the area of the partial image, an L-bit (L is a natural number) value is used for each pixel, and the first value in the data indicates that the image of the area is displayed as it is. The second value indicates a portion where the image outside the region is displayed as it is, and the other values indicate the portion where the image of the region and the image outside the region are superimposed. The above problem is solved by setting a value representing a mixture ratio of the image outside the region and the image outside the region.

<Operation> According to the configuration of the present invention described above, one or more partial images having an arbitrary shape are designated by their respective combining positions, and combined to form a plurality of desired images having different component image positions. As compared with the case where each of a plurality of desired images has image data independently, the data of each partial image can be shared, so that the entire data amount can be reduced, and the Compression encoding according to an image can be performed.

Hereinafter, an image compression method according to the present invention and a system for combining and displaying a plurality of image data using the image compression method (hereinafter, referred to as an “electronic presentation system”) will be described. FIG. 2 shows a hardware configuration diagram of a system used for an electronic presentation, and FIG. 3 shows a flow of image data in the present system.

This system is roughly classified into an editing system device and a display system device.

The display device is used to display images at presentations such as conferences and lectures.It has a large projector and multiple CRT monitors, and can display images created by editing devices, cursors and arrows. Such a pointer can be displayed on the screen, or an image change process set in advance by the editing system device can be executed during image display.

On the other hand, the editing device is for creating an image to be displayed on the display device, and edits and creates an image, sets a display order of a plurality of images, sets an image change process of an image being displayed, and changes the image. The setting of the switch for starting is performed.
A display program composed of image data, image display order data, image change processing data, and the like created by the editing device is written to a compact recording medium such as a floppy disk and transferred to the display device.

The system for synthesizing and displaying a plurality of image data using the image compression method according to the present invention shown in FIG. 2 is used as both the editing system device and the display system device. In the figure, reference numeral 20 denotes a full-color scanner, which is used to digitize and capture not only images such as photographs and paintings but also characters, texts, graphs and the like. Reference numerals 21 and 22 denote a keyboard and a mouse, respectively, which are used for inputting various operation instructions and file names. The CPU 23 controls the entire system, and has therein a memory and the like for storing various control programs. Image memory 24 is monitor 25
The image data to be displayed is written in. There is a capacity to store image data corresponding to several screens. The memory 26 is for temporarily storing a display program created by the editing device. The magneto-optical disk device 28 is a large-capacity storage device, and the image database shown in FIG.
Use as 32. On the other hand, the floppy disk device indicated by reference numeral 27 in FIG. 2 is used as an example of a compact recording device, and corresponds to the recording medium 34 in FIG. The DSP 29 is a digital signal processor that performs compression encoding and decoding of an image. Image memory 24 and DS
The transfer of image data or compressed data to / from P29 is performed by the CPU 23 via the FIFO or common memory shown in FIG. The common memory can switch between access from the CPU 23 and access from the DSP 29.

Next, an outline of the flow of image data will be described with reference to FIG.

In this method, not only color photographs but also characters, sentences, graphs, and the like are taken as images from the outside and created. That is, a full-color scanner 20 is provided as an image input unit, and a picture, a printed document, a word processor print output, etc. is input as an image, and scaling, affine transformation, coloring, shading, layout processing, etc. are performed, and image editing and creation are performed. . First, an image is captured using the full-color scanner 20. It can be captured from photographs, printed matter, or printed output of a word processor. The captured image is temporarily stored in the image database 32. As described above, in the present system, the magneto-optical disk 28 is used as the image database 32. The editing and creation of image data for presentation is performed by the editing system 33 fetching image data from the image database 32 as necessary and performing various processes while displaying the image data on the monitor 25. The components of the presentation image thus created are compressed using the image compression method according to the present invention, and are stored in the image database 32 again. Next, the editing system 33 creates a display program including position data for arranging the components, data of the image change processing, and the like, and stores the display program and the image data of the components in the storage medium. As described above, in the present system, the floppy disk device 27 is used as the storage medium. Display 35
Receives a display program and image data from the storage medium 34, creates an image from these data at the time of display, and gives a presentation.

Next, with reference to FIG. 1, FIG. 4, and FIG. 5, an image data editing / creating operation and an image compression method according to the present invention will be described, focusing on image data compression processing.

First, FIG. 4 shows a schematic processing flow. As shown by reference numeral 41, the original image is fetched into the image database 32 using the full-color scanner 20. At this time, generally, a full-color whole image and a character / graphic image such as a word processor output are separately input. Next, the character and graphic images that should be the components,
Extract full color full image and full color partial image and file them. This operation not only searches for the necessary image from the images stored separately in the image database 32 that are individually input as described above, but also cuts out the image to be treated as a partial image in the full-color whole image, A character graphic image in the entire image is cut out and the like. The image data as a component created in this way is once stored in the image database 32 again with an appropriate file name for compression processing. Thereafter, in step 43, compressed data is created and filed. FIG. 1 shows details of the creation of the compressed data and the filing. In the present embodiment, a file is once created before the compressed data is created.
Data compression processing may be performed directly after the creation of component parts. 1 to 3 in FIG. 1, the image file names of the component parts filed in 42 in FIG. 4 are input from the keyboard 21 or the mouse 22 or the like, and the image to be compressed while displaying the image data on the monitor 25 is displayed. Choose. Compressed data file names are assigned depending on whether the selected component is a character graphic image, a full color full image used as a background, or a full color partial image. This distinction is made by attaching an identifier to the beginning or end of the file name. The compressed data file name thus attached is input from the keyboard 21 or the like as shown in FIG. Next, if the input compressed data file name has an identifier of a character / graphic image, the first
The process branches from 5 to 10 in the figure to perform character / graphic image compression, and records the image in the image database 32 again. If the compressed data file name has the identifier of the full-color whole image, 6
If the compressed data file name has the identifier of the full-color partial image, the process branches from 7 to 8, and executes the optimal image compression method according to the nature or use of the image and records it again in the image database 32. Keep it.

Hereinafter, examples of the above three image compression methods will be described.

1. Character / graphic image compression method The character / graphic image compression method in this method is a compression method suitable for images having strong binary image characteristics such as characters and graphics. (Japanese Patent Application Nos. 63-281129, 1-109934, 1-
See 106328. The processing procedure first extracts only the luminance component of the image,
This is requantized, then divided into "target part" (parts such as characters and figures), "background part", and "halftone part", and encoded by a method based on run-length encoding. It is.

In the case of characters, figures, and the like, the shape and luminance information (or density information) for anti-aliasing are required, and the color information of the document may be separately provided at the time of decoding, and is not required at the time of encoding. Therefore, in the character / graphic image compression method, only the luminance component is compression-coded, and the color information of the document is discarded.

Next, the luminance component image is requantized to a required number of gradations. In the case of an ordinary display of about 500 × 500 pixels, quantization may be performed with 2 to 3 bits in consideration of the number of gradations required for anti-aliasing or the like. In the requantization, the pixel value of the target portion is set to the minimum value, the pixel value of the background portion is set to the maximum value by histogram processing, and
The quantization section is determined so as to divide between the two values by the required number of gradations, and the halftone part can be created only at the boundary between the target part and the background part. The tone portion is removed.

Next, the requantized image is encoded. A feature of the image to be encoded is that the number of halftone portions is very small. An encoding method using this feature will be described below. First,
Image with minimum pixel value (target part such as characters and figures)
And a portion having the maximum pixel value (background portion) and a halftone portion other than these. For the halftone portion, the image is further divided into bit planes 1 and 0. Of these, first, the minimum pixel value portion, the maximum pixel value portion, and the MS of the halftone portion
For the above four types of B values (0, 1), run lengths are obtained and variable-length encoded. The code of the run length is set to 2 so that it can be determined to which class the run belongs.
Flag the bits. In the image, the information of the pixel having the minimum pixel value and the maximum pixel value and the information of the MSB bit plane are processed by the above encoding. Then, for the remaining halftone portion, information on bit planes other than the MSB bit plane is encoded as follows. That is, a run length of 1, 0 is obtained for each plane, and variable length coding is performed. At this time, the minimum pixel value portion already coded,
The maximum pixel value portion is skipped, only the halftone portion is collected, the run length is obtained, and variable length encoding is performed. It is conceivable to use MH coding or MR coding for variable length coding.

2. Full Color Whole Image Compression Method The full color whole image compression method is a method for compressing an entire full color image, and uses a method of compressing by block coding. (See Japanese Patent Application Nos. 63-218019 and 63-254377.) Image data is converted to YIQ, and each YIQ image is compressed. First, the Y image is divided into blocks of 4 × 4 pixels.
In each block, the variance of the pixel values is checked and classified into three modes. In mode 0 with the smallest variance, only the average value of the pixels in the block is encoded. In Mode 1 with the next largest variance, an average value, one difference value, and one bit plane are created, and when decoded, the pixel value in the block is set to 2
Encoding so that it can be represented by two representative values. Further, in Mode 2 having the largest variance, an average value, a difference value, and two bit planes are created and, when decoded, are coded so that pixel values can be represented by four representative values. In the I and Q images, since detailed information is not required as much as the Y image, each block is divided into 4 × 4 pixels, and each block is encoded in mode 0 or mode 1 only. At the time of reproduction, filter processing for reducing block distortion is performed.

3. Full-color partial image compression method The full-color partial image compression method is a method of compressing and encoding only a partial area in a full-color image. (See Japanese Patent Application Nos. 60-195354 and 61-66819, 68820, 66821.)
The shape of the region is arbitrary, and the region may have holes. The region is represented with data indicating whether the region is a region or a boundary portion for each pixel. This data is called area information. The area information is information of L bits for each pixel, and when the value is 2 ^L −1, inside the area, when the value is 0, outside the area, that is,
The background is shown, and when the value is 1 to 2 ^L -2, the boundary portion is shown. When performing the superimposition process of the full-color partial images, this value is a value representing the mixture ratio of each pixel of the full-color partial image to be superimposed and the background image. In order to create the area information of the partial image from the original image, a method of extracting a color difference using a color difference between the target object and the other background is used. In the coding of the area information, the pixels having the values 0 and 2 ^L -1 are run-length coded, and otherwise, the original value is used as the code. Alternatively, since the properties of the area information are the same as those of the character graphic image described above, a method of compressing the character graphic image may be used.

The image information is coded only in a portion where the area information has a value of 2 ^L −1. At the boundary portion, the image information of the original image is interpolated from the pixel values in the area during reproduction without encoding. Image information is encoded using the same compression method as the full-color whole image compression method. When an image is divided into blocks, only blocks including pixels in the area are processed. In the decryption process, first,
The area information is decoded. With this, it is possible to know where the area part (that is, the part where the image information must be reproduced) in the screen is, so that the reproduced image information is written into the area part. The portion other than the region is left as it is without performing the processing as it is. For the boundary portion, the decoded value of the pixel in the neighboring area and the pixel value of the background pixel at that position are mixed according to the value of the area information at that position, and the value is written.

An example of the compression method has been described above for each of the three types of image data.

Returning again to FIG. 4, the display program is created and edited at 44. By this operation, as shown in FIG. 5, a display program including data of the display order of each component and data of the image change processing is created. Here, memories for two images are prepared in the image memory 24 of FIG. 2 and are called a screen 1 and a screen 2, respectively. First, 100 in Fig. 5
Select an image for background with ~ 103. Next, in steps 104 to 109, it is determined whether or not to combine the partial image with the background image, and the file to be combined, the coordinates of the combining position, and the like are determined. In steps 110 to 114, a file of the character / graphic image to be combined with the image made in the above 100 to 109 and the coordinate value of the combination position are determined. Note that 10 in FIG.
Storing the restoration command name in 3,109,114 is for the purpose of error processing. The screen 2 is for saving the image before the composition. Editing of one presentation image is performed as described above, but actually, the above-described process is repeated to create a plurality of screens. The display program created in this way is temporarily stored in the memory 26.

Next, in FIG. 45, an image change process, a command for pointer display, and the like are added to the display program created at 44 to complete the display program.

Finally, at 46, the display program and the compressed data of the image used there are recorded on the recording medium. The recording medium 34 is divided in advance into an area for recording a display program and an area for recording compressed data of an image, and each data is stored in a separate area.

The data for composite display created in this way is carried to a conference hall or a lecture hall, where the composite display is performed. In the case of actually performing the composite display (47 in FIG. 4), the CPU 23 reads the display program recorded in the recording medium 34 from the display program.
The compressed data file names of a plurality of images to be combined and displayed are read. Next, the CPU 23 decompresses the compressed data corresponding to each file name by a decompression method corresponding to each compression method, and then superimposes and displays each image. Thus, one composite image is displayed. A conference or a lecture will be given by repeating the above composite display operation.

<Effects of the Invention> According to the present invention, one or more partial images having an arbitrary shape are designated by their respective combining positions and combined to obtain a plurality of desired images having different partial image positions. As a result, the data of each partial image can be shared as compared with a case where each of a plurality of desired images has image data independently, so that the entire data amount can be reduced, and each partial image corresponds to the partial image. Compression coding can be performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the image compression method of the present invention, FIG. 2 is a diagram of the system configuration of the present invention, FIG. 3 is an explanatory diagram of the flow of image data of the present invention, and FIG. FIG. 5 is a diagram for explaining a method of creating a display program of the present invention, and FIG. 6 is a diagram showing an example of a presentation screen. 20 ... Full color scanner, 21 ... Keyboard, 23 ...
CPU, 24 ... Image memory, 25 ... Monitor, 27 ... Floppy disk drive, 28 ... Magneto-optical disk drive, 29 ...
DSP, 30 ... manuscript, 32 ... image database, 33 ... editing system, 34 ... recording media, 35 ... display system, 36 ... projector.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Noriyoshi Kayoshi 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-60-212063 (JP, A) JP-A Sho 63-300673 (JP, A) JP-A-58-214959 (JP, A) JP-A-63-299680 (JP, A) JP-A-60-109381 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/41-1/419

Claims (6)

(57) [Claims] An image encoding apparatus for synthesizing and displaying a desired image from an entire image and one or more partial images having an arbitrary shape, comprising: an image extracting unit for extracting the partial image from an input image; ,
Position input means for arbitrarily specifying a synthesis position of each of the partial images; position data determining means for determining position data indicating a synthesis position of each of the partial images based on the specification by the position input means; Region shape encoding means for compressing and encoding data indicating the shape of the image, and dividing the image information inside the region of the entire image and the partial image into rectangular blocks of a predetermined size and performing compression encoding in block units. Performing image information encoding means, and storage means for storing the compression-encoded image information and the area shape encoded data, and the position data, the image information encoding means, in the partial image, Only the block including the data in the area of the partial image is compression-encoded, and the compression-encoded data has an identifier. Or rectangular overall image with no information, the image coding apparatus characterized by indicating which any shape of the part images with shape information. 2. An L-bit (L is a natural number) value representing a mixture ratio between an image of the region and an image outside the region is used for each pixel as data indicating the shape of the region of the partial image. The image encoding device according to claim 1, wherein: 3. An L-bit (L is a natural number) value is used for each pixel as data indicating the shape of an area of the partial image, and a first value in the data is an image of the area. Indicates the portion where the image outside the region is displayed as it is, the second value indicates the portion where the image of the region and the image outside the region are superimposed, and ,
The image encoding apparatus according to claim 1, wherein the value is a value indicating a mixture ratio of an image in the area and an image outside the area. 4. Decoding encoded data of a combined image obtained by combining an entire image and one or more partial images having an arbitrary shape, and generating a combined image based on position data indicating a combining position of the partial image. An image decoding device for compressing and encoding the encoded data, wherein the image information is a rectangular whole image without shape information or an arbitrary shape partial image with shape information by an identifier indicating A partial image judging means for judging whether or not the image is a partial image, and image information decoding for decoding the whole image or the encoded data of the partial image compressed and encoded in rectangular block units of a predetermined size in block units. A region shape decoding unit that decodes region shape encoded data when the determination unit determines that the partial image is a partial image; and a region shape decoding unit that arbitrarily specifies the partial image at the time of encoding. Using position data obtaining means for obtaining a combined position and data indicating the decoded shape, from the decoded partial image, only data in the area of the partial image is arranged based on the position data, and combined. An image decoding apparatus comprising: a synthesizing unit that performs 5. An L-bit (L is a natural number) value representing a mixture ratio between an image of the region and an image outside the region for each pixel, as data indicating the shape of the region of the partial image. The image decoding device according to claim 4, wherein: 6. An L-bit (L is a natural number) value is used for each pixel as data indicating the shape of the area of the partial image, and a first value in the data is an image of the area. Indicates a portion where an image outside the region is displayed as it is, and the other values are
5. The image decoding apparatus according to claim 4, further comprising: indicating a portion where the image of the region and the image outside the region overlap each other, and a value indicating a mixture ratio of the image of the region and the image outside the region. apparatus.