WO2011142204A1

WO2011142204A1 - Image encoding device, image decoding device and image decoding method

Info

Publication number: WO2011142204A1
Application number: PCT/JP2011/059271
Authority: WO
Inventors: 村上　智一; 佑人小松; 克行中村
Original assignee: 株式会社日立製作所
Priority date: 2010-05-12
Filing date: 2011-04-14
Publication date: 2011-11-17
Also published as: JP2011239280A

Abstract

Disclosed is an image encoding device for encoding a plurality of input images. The image encoding device is provided with: a region calculation unit which uses correlations of a plurality of input images to calculate region data, which indicates a first region and a second region, for each of the plurality of images; a frame encoder which encodes the first region by means of a first encoding method and encodes the second region by means of a second encoding method, in accordance with the region data calculated for each of the plurality of images; a region data encoder which uses correlations of the region data to encode the region data calculated for each of the plurality of images; and an output unit which associates each of the encoded plurality of images with the encoded region data and outputs said images and data.

Description

Image encoding apparatus, image decoding apparatus, and image decoding method

Import by reference

This application claims the priority of Japanese Patent Application No. 2010-110217 filed on May 12, 2010, and is incorporated herein by reference.

The present invention relates to an image encoding device, an image decoding device, and the like, and more particularly, to a technology for processing an image using CT (Computed Tomography), MRI (Magnetic Resonance Imaging), or the like.

Medical diagnostic imaging apparatuses that process images using techniques such as CT and MRI are known. CT is a technique for imaging a tomogram of a human body using radiation such as X-rays and MRI using a nuclear magnetic resonance phenomenon. The captured image is recorded as digital data in accordance with a standard system called DICOM (Digital Imaging and COmmunication in Medicine). In particular, when the recorded image is a medical image, the original data of the image needs to be recorded. Therefore, compression is performed by a compression method such as the JPEG-LS standard (ISO-14495-1495 / ITU-T T.87) which is a reversible lossless compression method.

The lossless compression method has a problem that the compression rate is lower than the lossy compression method, which is an irreversible compression method that allows image degradation. In order to solve this problem, Patent Document 1 discloses a method of increasing the compression ratio by compressing an important part in an image by a lossless compression method and compressing an unimportant part by a lossy compression method. .

JP-A-8-331367

Incidentally, a tomographic image of a human body or the like generally taken by a medical diagnostic imaging apparatus is a multi-slice image. A so-called moving image is also a multi-frame image in which one sequence is composed of a plurality of images.

When compressing and encoding such a plurality of images by combining the lossless compression method and the lossy compression method, a portion compressed by the lossless compression method and a portion compressed by the lossy compression method for each image. It is necessary to specify (display, record) the range. However, the technique disclosed in Patent Document 1 does not consider such a point and has a problem that it cannot be efficiently encoded.

The present invention takes the above-described problems into consideration, and an image that can be efficiently compression-encoded or decoded by combining a plurality of compression methods (particularly, lossless compression method and lossy compression method) with respect to a plurality of images. An object is to provide an encoding device, an image decoding device, and the like.

A typical example of the invention disclosed in the present application is as follows. That is, an image encoding apparatus that encodes a plurality of input images, and for each of the plurality of input images, a first region to be encoded by a first encoding method, and the first A region calculation unit that calculates region data indicating a second region to be encoded by a second encoding method different from the encoding method using the correlation of the plurality of images; Based on the region data of each image, the first region of each of the plurality of images is encoded by the first encoding method, and the second region is encoded by the second encoding method. A frame encoder that encodes the region data of each of the plurality of calculated images using a correlation of the region data, and each of the plurality of encoded images Is Characterized by comprising an output unit for outputting in association with the region data.

According to the embodiment of the present invention, it is possible to efficiently compress and encode or decode a plurality of images by combining a plurality of compression methods (particularly, lossless compression method and lossy compression method).

It is a block diagram which shows an example of the image coding apparatus of embodiment of this invention. It is a block diagram which shows an example of the image decoding apparatus of embodiment of this invention. It is a figure which shows the example of the area | region designation | designated method with respect to one image of embodiment of this invention. It is a figure which shows the example of the area | region designation | designated method with respect to one image of embodiment of this invention. It is a figure which shows the example of the area | region designation | designated method with respect to the several image of embodiment of this invention. It is a figure which shows another example of the area | region designation | designated method with respect to the several image of embodiment of this invention. It is a figure which shows another example of the area | region designation | designated method with respect to the several image of embodiment of this invention. It is a figure which shows the example which displays the area | region set with respect to the several image of embodiment of this invention. It is a figure explaining the image coding method of embodiment of this invention. It is a flowchart which shows an example of the image coding method of embodiment of this invention. It is a flowchart which shows an example of the image decoding method of embodiment of this invention. It is a flowchart which shows an example of the display method of the area | region set with respect to the several image of embodiment of this invention.

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

FIG. 1 is a block diagram showing an example of an image encoding device 100 according to an embodiment of the present invention. The image encoding apparatus 100 includes an area designation processing unit 101, a multiframe image buffer 102, a multiframe area calculation unit 103, a frame encoder 104, a reference frame buffer 105, a reference area data buffer 106, an area data encoder 107, and an image stream buffer 108. The data combination unit 109 is provided.

Hereinafter, a case where the image encoding apparatus 100 compresses and encodes a monochrome image such as a medical image will be described as an example. However, the present invention is not limited to this case. When the image encoding apparatus 100 compresses and encodes a color image, for example, the same processing may be performed for each of the R, G, and B planes.

In the following, a case where an image input to the image coding apparatus 100 is a multi-slice image such as CT or MRI will be described as an example, but the present invention is not limited to this case. In addition to multi-slice images taken by shifting the position with a single imaging device, the input images are different from time-sequential images obtained by photographing the same patient at different times, and the same part. It may be a set of images obtained by shooting with a type of device or a general moving image. That is, the input image is a series of continuous images that are spatially or temporally continuous. Hereinafter, one image of the plurality of images is referred to as an image or a frame. A frame is synonymous with a slice and a picture.

The region designation processing unit 101 designates a region (region data) for a plurality of input images (image data). Specifically, a lossless area and a lossy area are designated for each input image. The lossless area is an area that is reversibly compressed by a lossless compression method. The lossy area is an area that is irreversibly compressed by the lossy compression method. By specifying an important area of each image data as a lossless area and an unimportant area as a lossy area, efficient compression is possible. The designation of the area can be executed by the following method. That is, the user may individually specify the lossless area and the lossy area for each image. Alternatively, the user may specify an area for the first image, and the system may automatically specify the area of each other image with reference to the area specified for the first image. Good. Further, the system may automatically designate all image areas. In the following, an example will be described in which the user inputs the area data of the first image to the area designation processing unit 101, and the multi-frame area calculation unit 103 automatically designates the area of each other image. In the following description, it is assumed that there is one designated area, but there may be a plurality of designated areas. A method for designating an area will be described later with reference to FIG. The area designation processing unit 101 transmits information on the designated area to the multiframe area calculation unit 103.

The multi-frame image buffer 102 holds a plurality of input images. The multi-frame image buffer 102 transmits a plurality of input images to the multi-frame region calculation unit 103 and the frame encoder 104.

The multi-frame area calculation unit 103 calculates the area data of each other image transmitted from the multi-frame image buffer 102 based on the area data of the first image designated by the area designation processing unit 101. Thereafter, the calculated area data of each image is transmitted to the frame encoder 104 and the area data encoder 107. The multi-frame area calculation unit 103 creates area data of the second image based on, for example, the first image, the second image, and the area data of the first image. That is, when the first image is compared with the second image, and the object in the second image is an enlargement of the object in the area of the first image, the second image Enlarge the area data. The area of the first image is applied to the second image, the difference between the average luminance in the first image area and the average luminance outside the area, and the average luminance in the second image area. Also, the difference in average luminance outside the area may be compared, and the shape of the area of the second image may be changed so that the difference between the two becomes small. A method for designating a region for a plurality of images can be appropriately realized by applying existing image processing.

The frame encoder 104 compresses each image transmitted from the multiframe image buffer 102 by using the region data set by the multiframe region calculation unit 103 and the encoded image held in the reference frame buffer 105. Encode.

More specifically, the multiframe image buffer 102 is used by using the region data information set by the multiframe region calculation unit 103 and the pixel information in another encoded image held in the reference frame buffer 105. The pixel value of each pixel in the image transmitted from is predicted and encoded. Note that the region designated as the lossless region is encoded by the lossless compression method, and the region designated as the lossy region is encoded by the lossy compression method. Details of the encoding method will be described later.

The reference frame buffer 105 holds the information of the image encoded by the frame encoder 104 as a reference frame. This reference frame is used by the frame encoder 104 when another image is encoded. The image stream buffer 108 holds information on the image encoded by the frame encoder 104.

The area data encoder 107 compresses and encodes the area data of each image calculated by the multiframe area calculation unit 103 with reference to other encoded area data held in the reference area data buffer 106. The area data encoder 107 may compress and encode the difference data of both area data when the area data of a predetermined image and the area data of another image are the same or similar. Thereby, the amount of information can be reduced.

The reference area data buffer 106 holds the area data information encoded by the area data encoder 107 as reference area data. This reference area data is used by the area data encoder 107 when encoding area data of another image.

The data combining unit 109 combines the encoded data of each image held in the image stream buffer 108 and the encoded data of the area data output from the area data encoder 107 to generate an encoded stream. The encoded stream is output to the outside.

With the image encoding device 100 described above, each of a plurality of images can be divided into a lossless area and a lossy area, and can be efficiently compressed and encoded.

FIG. 2 is a block diagram showing an example of the image decoding apparatus 200 according to the embodiment of the present invention. The image decoding apparatus 200 includes a data separation unit 201, an area data buffer 202, an image stream buffer 203, an area data decoder 204, a reference area data buffer 205, a frame decoder 206, a reference frame buffer 207, an output image buffer 208, and a display synthesis unit 209. Is provided.

The data separation unit 201 separates the input encoded stream into encoded data of region data and encoded data of images. The encoded data of the area data is transmitted to the area data buffer 202. Also, the encoded image data is transmitted to the image stream buffer 203. The area data buffer 202 holds encoded data of area data. The image stream buffer 203 holds encoded image data.

The area data decoder 204 decodes the encoded data of the area data held in the area data buffer 202. Specifically, by combining the difference data obtained by decoding the encoded data of the area data held in the area data buffer 202 with the other decoded area data held in the reference area data buffer 205 Decode the region data. In this way, the area data of each image is calculated.

The reference area data buffer 205 holds the area data information decoded by the area data decoder 204 as reference area data.

The frame decoder 206 stores the encoded data of each image held in the image stream buffer 203, the area data of each image decoded by the area data decoder 204, and other decoded images held in the reference frame buffer 207. And decrypt using

The frame decoder 206 is transmitted from the image stream buffer 203 using the pixel information of the other decoded images held in the reference frame buffer 207 and the area data of each image calculated by the area data decoder 204. The pixels of each image are predicted and decoded. The frame decoder 206 reversibly decodes the area designated as the lossless area and irreversibly decodes the area designated as the lossy area.

The reference frame buffer 207 holds image information decoded by the frame decoder 206 as a reference frame. The output image buffer 208 holds each image decoded by the frame decoder 206 as an output image.

The display composition unit 209 synthesizes (superimposes) the region data of each image decoded by the region data decoder 204 and each image held in the output image buffer 208. Thus, the user can easily discriminate between a portion compressed by the lossless compression method (lossless region) and a portion compressed by the lossy compression method (lossy region). In particular, when the displayed image is a medical image, displaying the lossless area and the lossy area separately makes it easy to grasp which part of the image is the lossless area in diagnosing a disease. It is valid. Therefore, the display composition unit 209 may display the boundary between the lossless area and the lossy area with a conspicuous color. The display composition unit 209 may display the lossless area and the lossy area in different colors.

With the image decoding apparatus 200 described above, the encoded stream compressed and encoded by the image encoding apparatus 100 can be restored to the original image and displayed. In other words, the image encoding device 100 can record each of a plurality of images in a data format that enables easy-to-understand display for the user.

3A and 3B are diagrams for explaining an example of a region specifying method for one image according to the embodiment of the present invention. FIG. 3A shows an example in which an area (lossless area) is designated by an ellipse. FIG. 3B shows an example in which an area (lossless area) is designated by a rectangle.

When an area is designated by an ellipse as shown in FIG. 3A, the multiframe area calculation unit 103 uses the center coordinates (x, y), the major axis length a, and the minor axis length as the area designation data. Data O (x, y, a, b) combining b is recorded. When the area is designated by a quadrangle as shown in FIG. 3B, the multiframe area calculation unit 103 uses the pixel coordinates (x1, y1) at the upper left corner and the pixel coordinates (x2, y1) at the lower right corner as the data for area designation. Data R (x1, y1, x2, y2) combined with y2) is recorded.

Note that the area designation method is not limited to the case shown in FIGS. 3A and 3B. For example, the region may be specified using a polygon other than an ellipse or a rectangle. A plurality of areas may be designated instead of one area.

The designation of such an area is a process for dividing an image into a lossless area and a lossy area, that is, for dividing an image into areas. Instead of dividing an image into a lossless area and a lossy area, prepare multiple quantization steps in the lossy coding method (the degree of coding using the lossy coding method), and use these quantization steps to divide the image into regions. May be. That is, for example, it may be divided into a lossy area with a low degree of quantization (encoding degree) and a lossless area and a lossy area with a high degree of quantization (encoding degree) and a large loss.

FIG. 4 is a diagram showing an example of a region designation method for a plurality of images according to the embodiment of the present invention. In the following, a case will be described as an example where an area is designated using an ellipse as shown in FIG. 3A for a plurality of images.

When an area is specified using an ellipse for a plurality of images, the multi-frame area calculation unit 103 records the above-described data O (x, y, a, b) for each of the plurality of images. However, in general, the areas designated for each image are often close to each other and similar to each other. Therefore, when designating an area for a predetermined image, the area designation processing unit 101 may record only the difference from the area designated for the image immediately before the predetermined image. As a result, the data amount can be reduced and recording can be performed efficiently.

“Method 1” shown in FIG. 4 shows a first example of an area designating method for a plurality of frames i (i = 1 to 4). In this “method 1”, the multi-frame area calculation unit 103 records the above-described data O (x, y, a, b) as the area data of frame 1. On the other hand, as the area data of the second and

subsequent frames

2, 3 and 4, data combining only the change amount (difference) of the major axis length a and minor axis length b with respect to the previous frame. Record (da2, db2), (da3, db3), (da4, db4) respectively. That is, in this “method 1”, the center coordinate (x, y) of the ellipse is fixed, and the major axis length a and the minor axis length relative to the previous frame are used as the area data of the second and subsequent frames. Only the amount of change of b is recorded. As a result, the data amount can be reduced and recording can be performed efficiently.

“Method 2” shown in FIG. 4 shows a second example of an area designation method for a plurality of frames i (i = 1 to 4). This “method 2” is a case where the regions of the

frames

1, 2, 3, and 4 are exactly the same. In this case, the multi-frame area calculation unit 103 records the above-described data O (x, y, a, b) as the area data of frame 1. Also, n = 4 is recorded as the number of frames n in which the same area data as the area data of frame 1 continues. In this way, the multi-frame area calculation unit 103 collectively specifies areas of continuous frames. As a result, the data amount can be reduced and recording can be performed efficiently.

FIG. 5 is a diagram showing another example of the region specifying method for a plurality of images according to the embodiment of the present invention. In the following, as in FIG. 4, a case will be described as an example in which regions are designated using an ellipse as shown in FIG. 3A for a plurality of images.

Generally, the shape of the area designated for each successive image often changes gently. Therefore, the multi-frame area calculation unit 103 designates the area of each image as shown below.

In the example shown in FIG. 5, the multi-frame area calculation unit 103 first designates areas for the

frames

1 and 4 at both ends of the plurality of frames i (i = 1 to 4). Thereafter, the region data of the

intermediate frames

2 and 3 are generated by interpolation based on the region data of the

frames

1 and 4.

For example, when the area information of frame 1 is O (x1, y1, a1, b1) and the area information of frame 4 is O (x4, y4, a4, b4), the center coordinates of the ellipse of frame 2 (x2, y2) Can be calculated as in equations (1) and (2).

Similarly, the center coordinates (x3, y3) of the ellipse of frame 3 can be calculated as in equations (3) and (4).

As a result, four consecutive image areas can be designated using the area data (O (x1, y1, a1, b1) and O (x4, y4, a4, b4)) of the two images. it can. By generating region data by interpolation in this way, the amount of data can be reduced and recorded efficiently.

Note that the example shown in FIG. 5 and the example shown in FIG. 4 are combined, and O (x4, y4, a4, b4) and O (x1, y1, a1) are used instead of O (x4, y4, a4, b4). , B1) and the difference (dx4, dy4, da4, db4) may be used.

FIG. 6 is a diagram showing another example of the region specifying method for a plurality of images according to the embodiment of the present invention. In the following, as in FIGS. 4 and 5, an example in which a region is specified using an ellipse as shown in FIG. 3A for a plurality of images will be described.

Generally, it is very troublesome to manually set an area for a large number of images one by one. Therefore, the user manually sets the area data of the first image, and the multi-frame area calculation unit 103 automatically sets the area data of the second and subsequent images. In other words, the multi-frame area calculation unit 103 may set the area data of the second and subsequent images by reflecting the change of the second and subsequent images with respect to the area data of the first image.

In the example shown in FIG. 6, the first image is compared with the second image, and the object in the second image area is an enlargement of the object in the first image area. In this case, the area data of the second image is enlarged. The area of the first image is applied to the second image, the difference between the average luminance in the first image area and the average luminance outside the area, and the average luminance in the second image area. Also, the difference in average luminance outside the area may be compared, and the shape of the area of the second image may be changed so that the difference between the two becomes small. Further, the area data of the first image may be changed so that the difference between the two becomes small.

For example, a plurality of images are analyzed, and an area is set so that a target object is included in an image having the largest area that should be a lossless area. Thereafter, the set area is applied to an image other than the image in which the area is set. By setting the areas in this way, it is possible to set the areas of all the images based on one area data. The method of analyzing each image area and target can be realized by applying general image processing such as edge comparison, partial area histogram comparison, line-by-line histogram comparison, feature point comparison, etc. is there. In particular, based on the region data specified in the first image, the region data of the second and subsequent images can be set using a luminance gradient obtained by a technique such as Snakes or Region Growing. it can. As a result, it is possible to greatly reduce the trouble of setting the area data.

Designation of the area (ellipse center point, long axis, short axis) in the first image can be realized, for example, by displaying the same image on the screen and operating the user's mouse on the screen. In addition, instead of explicitly recording the area data as described above, the area data encoder 107 (see FIG. 1) and the area data decoder 204 (see FIG. 2) estimate the area from each image. Rules to be held may be held in advance. In this case, the multiframe area calculation unit 103 does not need to explicitly record area data. For example, when the region data encoder 107 or the region data decoder 204 holds a rule that a lossy region is composed only of a specific pixel value, the portion of the specific pixel value may be specified as a lossy region from each image. it can. This method is premised on that the pixel value indicating the lossy area does not include the pixel value indicating the lossless area, but has an advantage that the area data need not be transmitted.

FIG. 7 is a diagram showing an example of displaying areas set for a plurality of images according to the embodiment of the present invention.

When regions are set for a plurality of images by the method described with reference to FIGS. 4 to 6, the display composition unit 209 (see FIG. 2) displays each image and a plane (slice cross section) on which the regions are set. A cross section B that is a set of intersecting lines with A can be displayed in a manner in which the lossless area and the lossy area are distinguished. That is, it is possible to display an arbitrary cross section of the volume data generated based on each image in which the area is set in a manner in which the lossless area and the lossy area are distinguished. In particular, when the displayed image is a medical image, it is effective to display the lossless area and the lossy area separately. This is because it is possible to easily grasp which part of the image is a lossless area in the diagnosis of a disease. Detailed processing relating to display will be described later with reference to FIG.

FIG. 8 is a diagram for explaining the image coding method according to the embodiment of the present invention. A method in which the frame encoder 104 (see FIG. 1) predicts the pixel value of a predetermined image in units of pixels will be described with reference to FIG. In general pixel value prediction, not only the pixel values of other pixels in the same image but also the pixel values of pixels in other images are referred to. An example in which only pixel values are referred to is shown.

In the example shown in FIG. 8, pixel X is a pixel in the lossless area that is currently being encoded. On the other hand, the pixel A and the pixel B are encoded pixels located on the left and on the upper side of the pixel X, respectively. Pixel A is a pixel in the lossy area and is encoded by the lossy code method. Pixel B is a pixel in the lossless area, and is encoded by a lossless coding method. In this case, the frame encoder 104 predicts the pixel value of the pixel X from the pixel B. This is because the prediction accuracy can be improved by predicting from the pixel B in the same lossless region as the pixel X than by predicting from the pixel A in the lossy region different from the pixel X.

In this way, the compression rate can be increased by selecting the prediction source pixel based on the information of the region to which the pixel to be encoded belongs. Note that even when the pixel value of a pixel to be encoded is predicted using pixels in another image, the prediction accuracy can be increased by using information on a region to which the pixel to be encoded belongs. Thus, by compressing a plurality of images using the information of the region to which the pixel to be encoded belongs, the compression rate can be improved. However, although the correlation of a plurality of images is used in the generation of the area data, the correlation of the plurality of images may not be used in the image encoding. Conversely, the correlation between a plurality of images is not used in the generation of the area data, but the correlation between a plurality of images may be used in the image encoding.

FIG. 9 is a flowchart showing an example of the image encoding method according to the embodiment of the present invention. Here, an example of an image encoding method will be described with reference to FIG.

First, in step 901, the area designation processing unit 101 and the multi-frame image buffer 102 input multi-frame images (a plurality of images) (901). In step 902, the area designation processing unit 101 designates area data of a lossless area and a lossy area for the input image according to designation by the user (902). The area designation method is as described above.

Thereafter, in step 903, the multi-frame area calculation unit 103 calculates area data of each input image based on the area data designated in step 902 (903). The calculation method of the area data of each image is as described above.

In step 904, the frame encoder 104 calculates the image to be encoded stored in the multiframe image buffer 102 by the multiframe region calculation unit 103 with the other encoded images held in the reference frame buffer 105. The encoding is performed with reference to the encoded image data and the area data of the other encoded image and the encoded pixel information of the encoded image (904). In step 904, by referring to a plurality of images and region data, prediction accuracy can be improved and encoding can be performed efficiently. Further, by using the area data, it is possible to efficiently encode by combining the lossless coding method and the lossy coding method.

In step 905, the frame encoder 104 stores the information of the image encoded in step 904 in the reference frame buffer 105 as a reference frame (905). In step 905, the frame encoder 104 stores the information of the image encoded in step 904 in the image stream buffer 108.

In step 906, the area data encoder 107 refers to the area data of another encoded image stored in the reference area data buffer 106, and encodes the area data of the image to be encoded (906). The region data encoding method is as described above. As described above, the difference data between the area data of the image to be encoded and the area data of another image can be efficiently encoded by compressing and encoding.

In step 907, the area data encoder 107 stores the area data information encoded in step 906 in the reference area data buffer 106 as reference area data (907).

In step 908, the data combining unit 109 integrates the encoded data of each image stored in the image stream buffer 108 and the encoded data of the area data output from the area data encoder 107 to create an encoded stream. The generated encoded stream is output to the outside (908).

According to the image encoding method described above, each of a plurality of images can be divided into a lossless area and a lossy area, and compression encoding can be performed efficiently.

FIG. 10 is a flowchart showing an example of the image decoding method according to the embodiment of the present invention. Here, an example of an image decoding method will be described with reference to FIG.

First, in step 1001, the data separation unit 201 inputs an encoded stream (1001). In step 1002, the data separation unit 201 separates the input encoded stream into encoded data of region data and encoded data of an image (image stream) (1002). The encoded data of the area data and the encoded data of the image separated in step 1002 are transmitted to the area data buffer 202 and the image stream buffer 203, respectively.

In step 1003, the area data decoder 204 refers to other decoded area data stored in the reference area data buffer 205, and calculates area data of the decoding target image (1003). In step 1003, the area data decoder 204 decodes the encoded data of the area data of the decoding target image held in the area data buffer 202 to generate difference data. Thereafter, the generated difference data and other decoded region data stored in the reference region data buffer 205 are combined (combined) to decode the region data of the decoding target image.

In step 1004, the frame decoder 206 converts the decoding target image stored in the image stream buffer 203, other decoded images held in the reference frame buffer 207, and the region data decoded by the region data decoder 204. Then, decoding is performed with reference to the decoded pixel information of the decoding target image (1004).

In step 1005, the area data decoder 204 stores the area data information calculated in step 1003 in the reference area data buffer 205 as reference area data, and the frame decoder 206 stores the image data decoded in step 1004. Information is stored in the reference frame buffer 105 as a reference frame (1005). In step 1006, the output image buffer 208 stores the image decoded by the frame decoder 206 as output image data (1006).

In step 1007, the display composition unit 209 synthesizes and displays the region data of each image decoded by the region data decoder 204 and the output image data held in the output image buffer 208 (1007). Thereby, the user can easily discriminate between the lossless area and the lossy area. In particular, when the displayed image is a medical image, displaying the lossless area and the lossy area separately makes it easy to grasp which part of the image is the lossless area in diagnosing a disease. It is valid.

By the image decoding method described above, the encoded stream compressed and encoded by the above image encoding method can be restored to the original image and displayed. In other words, each of the plurality of images can be recorded in a data format that enables a user-friendly display by the above-described image encoding method.

FIG. 11 is a flowchart showing an example of a method for displaying an area set for a plurality of images according to the embodiment of the present invention. Here, an example of the display process described above will be described with reference to FIG.

First, in step 1101, the display composition unit 209 calculates an intersection line between a newly created slice section (plane) and each image in which a region is set (1101). For example, it is assumed that a multi-frame image is taken in a direction perpendicular to the body axis in taking a medical image using CT. When a new slice cross section is created on a plane parallel to the body axis based on the multi-frame image, the new slice cross section and each image intersect with a line. Therefore, the display composition unit 209 obtains an intersection line between a newly created slice cross section and each image.

Next, in step 1102, the display combining unit 209 acquires pixel information from each image and combines it with a new slice cross-sectional image (1102). In step 1102, the display synthesis unit 209 acquires pixel information on the intersection line calculated for each image in step 1101, and projects it onto a newly created slice cross section. Thereby, the pixel information on the intersection line of each image can be synthesized. Note that instead of acquiring pixel information from all images, the display composition unit 209 may acquire pixel information from some images and obtain image information of other images by interpolation based on the acquired pixel information. Good.

Thereafter, in step 1103, the display composition unit 209 calculates the intersection line and intersection point between the area set for each image and the new slice section (1103). In this embodiment, areas such as a lossless area and a lossy area are set in each image by an ellipse, a quadrangle, or the like. In this way, the region set for each image and the new slice cross section intersect at a line or a point. In particular, when the set area is a plane, it intersects with a line, and when the set area is a line, it intersects with a point. Therefore, the display composition unit 209 calculates an intersection line or intersection between the slice cross section and the region set for each image based on the positional relationship between the shooting position of each image and the newly created slice cross section. To do.

Thereafter, in step 1104, the display composition unit 209 sets an area on a new slice section (1104). In step 1104, the display composition unit 209 projects the intersection line and intersection calculated in step 1103 onto a new slice cross section. Thereby, the user can easily discriminate between the lossless area and the lossy area.

Thereafter, in step 1105, the display synthesis unit 209 synthesizes (superimposes) the new slice cross-sectional image created in step 1102 and the region set in step 1104 (1105). In particular, when the displayed image is a medical image, it is possible to distinguish and display the lossless area and the lossy area in order to easily grasp which part of the image is the lossless area in the diagnosis of a disease. It is valid. Therefore, the display composition unit 209 may display the colors of the boundary between the lossless area and the lossy area by color coding or highlight the boundary. In addition, the display composition unit 209 may display the boundary between the lossless area and the lossy area as a line.

For example, the image encoding method and the image decoding method according to the embodiment of the present invention may be applied to an image recording apparatus and an image transmission apparatus. Accordingly, it is possible to provide a medical diagnostic imaging apparatus capable of recording a large volume of images and transmitting an image with a small bandwidth, and an imaging apparatus such as CT and MRI.

Although the present invention has been described in detail with reference to the accompanying drawings, the present invention is not limited to such specific configurations, and various modifications and equivalents within the spirit of the appended claims Includes configuration.

Claims

An image encoding device for encoding a plurality of input images,
For each of the plurality of input images, a first region to be encoded by a first encoding method and a second region to be encoded by a second encoding method different from the first encoding method An area calculation unit that calculates area data indicating the correlation between the plurality of images;
Based on the calculated region data of each of the plurality of images, the first region of each of the plurality of images is encoded by the first encoding method, and the second region is encoded by the second region. A frame encoder for encoding by an encoding method;
An area data encoder that encodes the calculated area data of each of the plurality of images using the correlation of the area data;
An output unit that associates and outputs each of the plurality of encoded images and the encoded region data;
An image encoding apparatus comprising:
The image encoding device according to claim 1,
When the plurality of images are a series of consecutive images, the region data encoder is configured to calculate difference data between region data of a predetermined image and region data of an image adjacent to the predetermined image. An image encoding device that encodes as region data.
The image encoding device according to claim 1,
When the plurality of images are a series of consecutive images, the region calculation unit is configured to determine the first image and the second image based on region data specified for the first image and the second image. An image coding apparatus characterized in that region data of a third image located in the middle of the image is calculated by interpolation.
The image encoding device according to claim 1,
When the plurality of images are a series of consecutive images, the region calculation unit obtains region data of each of the second and subsequent images based on region data designated by the user for the first image. An image encoding apparatus characterized by calculating.
An image decoding device that decodes an encoded stream including encoded data of a plurality of images and encoded data of area data of each of the plurality of images,
The area data is data indicating a first area to be decoded by the first decoding scheme and a second area to be decoded by the second decoding scheme,
A data separator that separates the encoded stream into encoded data of the plurality of images and encoded data of the plurality of region data;
An area data decoder that decodes the encoded data of the plurality of area data separated by using the correlation of the area data;
Based on the decoded plurality of region data and the encoded data of the plurality of separated images, the first region of each of the plurality of images is decoded by the first decoding method, A frame decoder for decoding a second region by the second decoding method;
A display unit for displaying the plurality of decoded region data and the plurality of decoded images in association with each other;
An image decoding apparatus comprising:
The image decoding device according to claim 5,
The display unit displays a predetermined cross-sectional image of volume data generated based on the plurality of decoded region data and the plurality of decoded images, as the first region and the second region. An image decoding apparatus characterized by displaying in a distinguished form.
The image decoding device according to claim 6,
The display unit newly sets a predetermined plane for display,
Calculating a line of intersection between the predetermined plane and each of the plurality of decoded images;
From each of the plurality of images, obtain pixel information on the calculated intersection line, project the obtained pixel information on the predetermined plane,
Calculating an intersection line or intersection between the predetermined plane and the decoded plurality of area data;
An image decoding apparatus characterized in that the calculated intersection line or intersection point information is projected onto the predetermined plane in a manner distinguished from the plurality of images.
The image decoding device according to claim 5,
When the region data decoder decodes the encoded data of the predetermined region data among the encoded data of the plurality of separated region data, the region data of the image in which the encoded data of the predetermined region data is adjacent The difference data obtained by decoding the encoded data of the predetermined area data is synthesized with the decoded area data of an image adjacent to the predetermined image, thereby obtaining the predetermined area. An image decoding apparatus that decodes encoded data of data.
An image decoding method for decoding an encoded stream including encoded data of a plurality of images and encoded data of area data of each of the plurality of images,
The area data is data indicating a first area to be decoded by the first decoding scheme and a second area to be decoded by the second decoding scheme,
Separating the encoded stream into encoded data of the plurality of images and encoded data of the plurality of region data;
Decoding the encoded data of the plurality of region data separated using the correlation of the region data;
Based on the decoded plurality of region data and the encoded data of the plurality of separated images, the first region of each of the plurality of images is decoded by the first decoding method, A procedure for decoding a second region by the second decoding method;
A procedure for displaying the plurality of decoded region data and the plurality of decoded images in association with each other;
An image decoding method comprising:
The image decoding method according to claim 9, comprising:
In the displaying step, a predetermined cross-sectional image of volume data generated based on the plurality of decoded region data and the plurality of decoded images is converted into the first region and the second region. An image decoding method, characterized in that the image is displayed in a distinguished manner.
The image decoding method according to claim 10, comprising:
In the displaying procedure, a predetermined plane for display is newly set,
Calculating a line of intersection between the predetermined plane and each of the plurality of decoded images;
From each of the plurality of images, obtain pixel information on the calculated intersection line, project the obtained pixel information on the predetermined plane,
Calculating an intersection line or intersection between the predetermined plane and the decoded plurality of area data;
An image decoding method characterized in that the calculated intersection line or intersection point information is projected onto the predetermined plane in a manner distinguished from the plurality of images.