JP3242769B2 - Image coding restoration method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lossless encoding of an entire image and lossless encoding of a specified partial area in an image when encoding medical image data, and lossless encoding of the entire image at the time of restoration. The present invention relates to an image coding restoration method and apparatus for reversibly restoring a loss-encoded partial area after restoration.

[0002]

2. Description of the Related Art In medical institutions such as hospitals, medical images such as X-ray images and CT images obtained from patient diagnosis are used. Because the medical image includes lesions and obstructions in the patient,
It is necessary to keep it for seeing changes in symptoms and to use it for research purposes, and the law also requires that it be kept for a certain period of time. Therefore, the number of medical images obtained from patient diagnosis and the like is increasing, and a means for saving space in an image storage place is required.

[0003] Therefore, code data obtained by reversibly encoding medical image data is stored in a magnetic recording device or a magneto-optical recording device.
A method has been proposed in which a stored image is read using search data and a restored image is displayed. However, since lossless encoding is performed as an image encoding method, the amount of encoded data is increased, the capacity of a recording device for storing the encoded data is increased, and it takes time to transfer data. There is a need to reduce the code data to reduce the data transfer time.

As described above, in the conventional method for restoring the encoding of a medical image, at the time of image encoding, the entire image to be stored is reversibly encoded, and the generated encoded data is stored in a magnetic recording device or the like. At the time of image restoration, code data for a target image is retrieved and then restored and displayed.

[0005]

In the conventional method, it is said that the code data becomes large in order to reversibly encode the entire medical image, so that it takes a long time to increase the capacity of a recording device for storing and transfer data. There was a problem. The present invention
Based on the above considerations, it is possible to reduce the amount of code data when converting and storing medical images into code data, and to completely restore images without losing important information necessary for diagnosis. It is an object of the present invention to provide an encoding restoration method and apparatus.

[0006]

SUMMARY OF THE INVENTION In a medical diagnosis using a medical image, the present invention is not required to encode the entire image in a lossless manner, because the necessary and important information in the image is a diseased part. Only the image of the diseased part is extracted and losslessly encoded, and the entire image is irreversibly encoded to reduce the amount of code data. By replacing the more restored area with the corresponding area of the previous image, it is possible to completely restore the important portion necessary for diagnosis without losing information.

According to a first aspect of the present invention, there is provided an image encoding and restoring method, wherein an irreversible encoding process of irreversibly encoding the entire image to generate irreversible encoded data, and an image of a plurality of designated partial areas in the image. A lossless encoding process of losslessly encoding each of the data to generate lossless encoded data, an irreversible restoration process of generating a restored image of the entire image from the irreversibly encoded data, and selecting a partial region from the plurality of partial regions And a lossless restoration process of generating a restored image of the partial region from the lossless code data of the selected partial region, and a process of combining the irreversibly restored image and the lossless restored image. It is characterized by the following.

According to a second aspect of the present invention, there is provided an image encoding apparatus for irreversibly encoding entire image data to generate irreversible data, and for specifying a partial area to be extracted in the image. Area designating means (202), and the area designating means
(202) a partial image extracting means for extracting partial image data of the partial area specified by (202), and lossless encoding of the partial image data extracted by the partial image extracting means (203) to generate lossless code data And a reversible encoding means (207).

[0009] Image coding apparatus according to claim 3, in the image encoding apparatus according to claim 2, counting means for generating a count information by counting the number of the extracted partial region the partial image data (2
05).

According to a fourth aspect of the present invention, there is provided an image restoration apparatus for recovering an image from irreversible code data, and code data storage for storing lossless code data, position information, and count information of a plurality of partial areas. Means (303), restoration area designating means (304) for designating a partial area to be restored, and reversible code data and position information of a plurality of partial areas stored in the code data storage means (303). The restoration area designating means
(305) code data selection means for selecting reversible code data and position information of the partial area designated by (304), and reversible restoration for restoring a partial image from the lossless code data selected by the code data selection means (305) Means (308), and image combining means (310) for combining the image restored by the irreversible restoring means (307) and the partial image restored by the lossless restoring means (308). Is what you do.

[0011]

[Action] FIG 1 is a diagram for explaining an image coding restoration method of claim 1. FIG. 1A is a diagram for explaining image coding. First, the entire medical image is irreversibly encoded. Next, the partial areas A, B, and C including the lesion are designated, and the partial areas A,
B and C are losslessly encoded. FIG. 1B is a diagram for explaining image restoration. The entire image is restored by irreversibly restoring the irreversible code data of the entire image. Next, the partial image of the partial area A is restored by reversibly restoring the lossless code data of the partial area A. Next, the image of the partial area A in the entire image obtained by the irreversible restoration is replaced with the image of the partial area A obtained by the lossless restoration. Partial area B,
Similar processing is performed for C. Only a desired partial area of the partial areas A, B, and C may be restored.

The operation of the image coding apparatus according to claim 2 will be described. The irreversible encoding means (206) performs irreversible encoding on the entire image. The area designating means (202) designates a partial area to be extracted in the image, and generates position information of the partial area. The position information indicates the position and size of the partial area. The partial areas A, B, and C in FIG. 1 correspond to the partial areas to be extracted in the image. Partial image extraction means (203)
Extracts the partial image data of the partial area specified by the area specifying means (202), for example, from the image memory.
The lossless encoding means (207) losslessly encodes the partial image data extracted by the partial image extraction means (203).

The operation of the image coding apparatus according to claim 3 will be described. The image encoding apparatus according to claim 3 is characterized in that the counting means (20
5) is different from the image encoding device of claim 2 in that Assuming that lossless encoding is performed in the order of the partial areas A, B, and C in FIG. 1, the number of the partial area A is 1, the number of the partial area B is 2, and the number of the partial area C is 3. .

The operation of the image restoring device according to claim 4 will be described. The irreversible restoration means (307) restores an image from the irreversible code data. The code data storage means (303) stores lossless code data, position information, and count information of a plurality of partial areas. The restoration area designating means (304) designates a partial area to be restored. Code data selection means (305)
Selects lossless code data and position information corresponding to the designated partial area from the code data storage means (303).
The reversible restoration means (308) reversibly restores the selected reversible code data. The image synthesizing means (310) is irreversible
The image restored in step 07) and the partial image restored in the reversible restoration means (308) are combined.

[0015]

FIG. 2 is a diagram showing an embodiment of an image coding apparatus according to the present invention. In the figure, reference numeral 201 denotes image data; 202, an area designation unit; 203, a partial image extraction unit;
05 is a counting section, 206 is a lossy coding section, 207 is a lossless coding section, 208 is position information, 209 is counting information, 21
0 indicates lossy code data, and 211 indicates lossless code data.

The image data 201 is stored in an image storage unit (not shown), and an image based on the image data 201 is displayed on a screen of an image display device. Area designator 2
02, the partial image extraction unit 203, the counting unit 205, and the like are realized by a computer system including a position information input device such as a mouse and an image display device. The area specifying unit 202 requires an input device such as a mouse for specifying a position in an image. An example of such a computer is a CRT
There is an engineering workstation with a display, keyboard and mouse. It goes without saying that the computer has programs for area designation, partial image extraction, and counting.

The area designation will be described. A medical image such as a CT image to be compressed is displayed on the display screen. An operator, such as a doctor or a diagnostician, operates a pointing device such as a mouse to select a region to be losslessly encoded, for example, as a rectangle from the image displayed on the display. The designated area is displayed by surrounding it with a frame so that it can be distinguished from other parts. By pressing the execution key, it is determined that the selected area is a partial image, and the area specification is completed.

As described above, when the operator looks at the image on the display screen, specifies a partial area to be extracted using a mouse or the like, and presses the execution key, the area specifying unit 202 The position and the size for specifying the region are notified to the partial image extracting unit 203 and output as position information 208 to activate the partial image extracting unit 203. At the same time, the counting unit 205 is notified that the execution key has been pressed, and upon receiving this notification, the counting unit 205 increments the count value by one. The position information 208 indicates the coordinate value of the upper left corner of the specified partial area in the screen coordinate system and the number of vertical and horizontal pixels of the specified partial area.

When the partial image extracting unit 203 is activated,
With reference to the position information and size information of the partial area designated by the area designating unit 202, partial image data corresponding to the designated partial area is extracted from the image storage unit (not shown), and the extracted part The image data is input to the lossless encoding unit 207.

The lossy encoding unit 206 converts the image data into a D
CT transform (Discrete Cosine Transform), the result is quantized, and the result is Huffman-coded.
The image data 201 is input to the lossy encoding unit 206. The lossless encoding unit 207 converts the image data into a DPCM (Dif
ferential Pulse Code Modulation), and the result is Huffman-coded. Lossless encoding unit 207
Contains partial image data extracted by the partial image extraction unit 203 (image data corresponding to a specified partial area)
Is entered.

The operation of the image coding apparatus shown in FIG. 2 will be described. First, the entirety of the input image data 201 is irreversibly encoded by the irreversible encoding unit 206, and the irreversible encoded data 2
Generate 10. On the other hand, the region specifying unit 202 specifies a partial region to be extracted in the image, instructs the partial image extracting unit 203 and the counting unit 205, and outputs the position and size of the extracted partial image as position information 208. The partial image extracting unit 203 converts the designated partial area into the input image data 2
01 and sent to the lossless encoding unit 207.

A lossless encoding unit 207 losslessly encodes the received image data of the partial area to generate lossless encoded data 211.
Generate The counting unit 205 counts the number of times the extraction of the partial area is instructed, and counts the count value each time the counting is performed.
9 is output. To extract multiple subregions,
The area specification unit 202 repeatedly specifies the partial area, and generates lossless code data 211, position information 208, and count information 209 for each of the plurality of extracted partial images.

FIG. 3 is a diagram showing an embodiment of an image restoration apparatus according to the present invention. In the figure, reference numeral 301 denotes lossy code data, 302 denotes lossless code data, 303 denotes a code data storage unit, 304 denotes a restoration area designation unit, 305 denotes a code data selection unit, 306 denotes count information, 307 denotes a lossy restoration unit, 3
08 is a reversible restoration unit, 309 is an image data storage unit, 310
Denotes an image synthesis unit, 311 denotes position information, and 312 denotes an image display device.

The count information 306 and the position information 311 are stored in a storage medium such as a magnetic disk together with the irreversible code data 301 and the lossless code data 302. Further, the position information 311 and the count information 306 are respectively attached to the reversible code data 302 of one partial area.
11 and the count information 306 are stored in association with the lossless code data 302 of the partial image corresponding thereto. When restoring,
These three pieces of data of the plurality of partial areas are stored in the code data storage unit 303, and are selected by the designation of the restoration area designation unit 304.

An irreversible restoration unit 307 receives irreversible code data of the entire image. The irreversible restoration unit 307 performs Huffman decoding of the irreversible code data, inversely quantizes the resulting data, and performs inverse DCT on the resulting data.
It is something to convert. Image data output from the irreversible restoration unit 307 is stored in the image data storage unit 309. The data in the image data storage unit 309 is stored in the image display device 3
12 and the image is displayed on the screen of the image display device 312. The code data storage unit 303 stores a plurality of pieces of reversible code data 302 of a partial area, position information 311 corresponding to each partial area, and a plurality of pieces of count information 306.

The restoration area designating section 304, code data selecting section 305, image synthesizing section 310 and the like are realized by a computer system having a position information input device such as a mouse and an image display device. The restoration area designation unit 304 needs an input device such as a mouse for designating a position in an image. An example of such a computer is an engineering workstation equipped with a CRT display, keyboard and mouse. It goes without saying that a computer has a program for specifying an area, selecting code data, and synthesizing an image.

The specification of the restoration area will be described. First, the irreversible code data of one entire image is restored and displayed on a display. If there is a partial image to be extracted, the position indicated by the position information of the partial area and the count value are displayed on the screen. The display method is as follows: the area where the partial area exists is surrounded by a frame, and the counting information is displayed in the frame, for example, which part in the image has the partial area and which part number is the partial area. To understand. An operator such as a doctor selects a partial area to be viewed in detail by clicking with a mouse or inputting a number from a keyboard, and the restoration area designation is completed.

As described above, on the screen of the image display device 312, information indicating the losslessly encoded partial area is displayed. When the operator designates a partial area to be reversibly restored and presses the execution key, the restoration area designation unit 304 changes the count information 306 corresponding to the partial area into the code data selection unit 30.
5 and activates the code data selection unit 305.

When activated, the code data selection unit 305 refers to the partial region count information 306 input from the restoration region designation unit 304 and stores the code data and position information of the corresponding partial region in the code data storage unit. Read from 303,
The read code data is input to the lossless restoration unit 308, and the position information is sent to the image synthesis unit 310. The lossless restoration unit 308 performs Huffman restoration of the input code data, and performs inverse DPCM conversion on the data obtained as a result. The image data restored by the reversible restoration unit 308 is sent to the image synthesis unit 310.

The position information 311 corresponding to the image data of the partial area output from the lossless restoration unit 308 selected by the code data selection unit 305 is input to the image synthesis unit 310. The image combining unit 310 refers to the input position information 311 and replaces the image data corresponding to the partial area in the image data storage unit 309 with the image data sent from the reversible restoration unit 308.

The operation of the image restoration device shown in FIG. 3 will be described. First, the irreversible code data is restored by the irreversible restoration unit 307, and then sent to the image data storage unit 309. The image data storage unit 309 stores the restored image data received from the irreversible restoration unit 307, and stores the restored image data in the image display device 31.
Send to 2.

On the other hand, the restoration area designation section 304 designates a partial area to be restored among the plurality of partial areas, and instructs the code data selection section 305. Based on the count information 306 received from the restoration area designating unit 304, the code data selecting unit 305 extracts the designated count information 306 from the plurality of lossless code data 302 and position information 311 stored in the code data storage unit 303 in advance. The code data and position information for the image of the partial area corresponding to are selected, the code data is sent to the lossless restoration unit 308, and the position information is sent to the image synthesis unit 310.

The reversible restoring section 308 is provided with the code data selecting section 3
05 is reversibly restored and sent to the image synthesizing unit 310. The image synthesizing unit 310 stores the position information 3 of the image data stored in the image data storage unit 309.
The partial image received from the reversible restoration unit 308 is combined with the position indicated by 11. The image data storage unit 309 newly sends out the synthesized image to the image display device 312. When restoring a plurality of areas, the restoration area designation unit 304 repeats the designation of the restoration area, and sets the count information 3 corresponding to each restoration area.
06, and sequentially restore the partial images based on the position information 311.

FIGS. 4 and 5 are diagrams for explaining the effect of the present invention. FIG. 4 is a diagram for explaining the operation at the time of image encoding. In the related art, all of the input image data is losslessly encoded. The resulting amount of code data is very large. In the present invention,
The entire input image is irreversibly encoded, and only the partial region including the lesion in the input image data is losslessly encoded. In the illustrated example, the partial areas including the lesion are defined as partial areas A, B, and C. The image data of the partial area A, the image data of the partial area B, and the image data of the partial area C are extracted from the input image data, the image data of the partial area A is losslessly encoded, and the image data of the partial area B is then losslessly encoded. Then, the image data of the partial area C is losslessly encoded. According to the present invention, the amount of code data is reduced to about 1/5 compared to the prior art.

FIG. 5 is a diagram for explaining the operation at the time of image restoration according to the present invention. First, the entire image is restored by irreversibly restoring the irreversible code data of the entire image. Next, the reversible data of the partial area A is reversibly restored, and the image of the area A already displayed is replaced with the image of the area A obtained by reversibly restoring. Then, the reversible data of the partial area B is restored and the already displayed image is displayed. Of the region C obtained by reversibly restoring the image of the region C obtained by reversibly restoring the image of the region C obtained by reversibly restoring the image of the region C Replace with image.

[0036]

As is apparent from the above description, according to the present invention, since the entire image is irreversibly coded and a necessary area of the image is extracted and lossless coded, the code data of the image can be reduced. And the effect that the encoding / restoring time can be shortened. In addition, it is possible to extract only a plurality of areas and perform lossless encoding, and at the time of restoration, select and restore the extraction area to completely restore only the necessary parts, which improves the efficiency of medical diagnosis using medical images. Can contribute.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram illustrating an embodiment of an image encoding device according to the present invention.

FIG. 3 is a diagram illustrating an embodiment of an image restoration device according to the present invention.

FIG. 4 is a diagram illustrating the effect of the present invention.

FIG. 5 is a diagram (continued) for explaining the effect of the present invention.

[Explanation of symbols]

 Reference Signs List 201 image data 202 area designation unit 203 partial image extraction unit 205 counting unit 206 lossy coding unit 207 lossless coding unit 208 position information 209 count information 210 lossy code data 211 lossless code data 301 lossy code data 302 lossless code data 303 code data storage unit 304 restoration area designation unit 305 code data selection unit 306 count information 307 irreversible restoration unit 308 reversible restoration unit 309 image data storage unit 310 image synthesis unit 311 position information 312 image display device

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-305666 (JP, A) JP-A-62-75773 (JP, A) JP-A-2-273875 (JP, A) JP-A-3-273 104380 (JP, A) JP-A-5-110737 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1/41-1/419 A61B 6/00 H04N 7/24

Claims (4)

(57) [Claims] An irreversible encoding process for irreversibly encoding the entire image to generate irreversible encoded data, and a lossless encoding by lossless encoding each of image data of a plurality of designated partial areas in the image. A lossless encoding process for generating data; an irreversible restoration process for generating a restored image of the entire image from the irreversible code data; selecting a partial region from the plurality of partial regions; and a lossless code for the selected partial region. An image encoding / restoring method, comprising: a reversible restoration process of generating a restored image of a partial area from data; and a process of combining the irreversibly restored restoration image and the lossless restored image. . 2. An irreversible encoding means for irreversibly encoding the entire image data to generate irreversible data; an area designating means for designating a partial area to be extracted in the image; A partial image extracting unit that extracts partial image data of a specified partial region; and a lossless encoding unit that generates lossless encoded data by losslessly encoding the partial image data extracted by the partial image extracting unit. An image encoding device characterized by the following. 3. The image encoding apparatus according to claim 2 , further comprising a counting unit that counts the number of partial areas from which the partial image data is extracted to generate count information. 4. An irreversible restoration means for restoring an image from irreversible code data, code data storage means for storing lossless code data of a plurality of partial areas, position information and count information, and a partial area to be restored From among the lossless code data and the position information of the plurality of partial areas stored in the code data storage means, and the reversible code data of the partial area designated by the restoration area specifying means. Code data selecting means for selecting position information; lossless restoring means for restoring a partial image from the lossless code data selected by the code data selecting means; an image restored by the irreversible restoring means; An image synthesizing means for synthesizing a restored partial image with an image synthesizing device.