JPS5937933A - Image data collecting apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image data acquisition device for capturing cardiac dynamic image data at high speed and over a long period of time using, for example, radioisotope-1 or X-rays.

[Technical background of the invention]

For example, in the medical field, analog methods such as film-based recording or video recording equipment are often used to record X-ray images or radioisotopes of affected areas.

However, in recent years, there has been a trend toward an increasing proportion of digital data being recorded, stored, or processed in place of this analog method.

In this case, a problem arises when the object is something that moves rapidly, such as the heart, and it is necessary to obtain dynamic images of the object over a long period of time.

To withstand advanced diagnostics in medical imaging, it is necessary to collect original images in digital format without reducing image quality.
For example, when obtaining an image of the heart using X-rays, the number of pixels per frame is 512 x 512, and the information M (gradation) of one pixel is 28 (the data amount of 28 is the capacity of 8 bits). ), it is also necessary to collect data for at least 10 seconds at -30 images (30 frames) per second.

The image data transfer speed when collecting this is 512x5
12X8X30 data is 7.8 megabytes per second, or 578 megabytes.

Incidentally, at present, a magnetic disk device is considered to be the closest means for storing such huge amounts of data, considering aspects such as economic efficiency and reliability.

In terms of capacity, if you take a method where you input data for one item and process it, and then input and process the data for the next item after processing, it will take about 100 megabytes. Capacity disks are commonly used, so capacity issues are minor.

However, the transfer speed remains a major problem.

In other words, the transfer speed of general magnetic disk devices currently used in minicomputers, etc. is around 11 megabytes/second,
As a result, image data sent from cameras, etc. at a speed of 7.8 megabytes/second cannot be stored in time. For this reason, various institutions in Japan and abroad have attempted to use a semiconductor memory, which has a transfer speed 2.3 orders of magnitude faster than a magnetic disk device, as a buffer memory. A method is used in which all the data is stored in the magnetic disk device by sequentially transmitting the storage data at a transfer speed that the magnetic disk device can respond to, or the number of pixels of the image is reduced to 128 x 128.
Alternatively, reduce the amount of data that can be obtained per second by reducing the amount of data that can be obtained per second, thereby reducing the necessary transfer rate and keeping it within the transfer rate that can be handled by the magnetic disk device. Methods such as making it possible to import data are being considered.

However, a method that uses a large amount of semiconductor memory as a buffer memory has problems in terms of memory cost, and a method that reduces the number of pixels has problems in terms of image quality.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and is designed to allow multiple frames of compressed single-image data to be compressed into inexpensive equipment in a short period of time without deteriorating image quality. The purpose of this invention is to provide an image data acquisition device that increases speed and reduces system costs.

[Summary of the invention]

That is, in order to achieve the above object, the present invention includes means for digitally converting an image signal, a memory having a capacity for a plurality of frames and sequentially storing the digitally converted data, and used for calculations and data storage; Based on the digital conversion data stored in this memory, the time series -L
an arithmetic unit that obtains data of subtraction images (images of differences between pixels at the same position) of adjacent frames and also obtains data of differences between pixels at positions adjacent to each pixel in the subtraction images of the subframe and supplies the data to the memory; comprising: a data compression storage means (9) comprising a control section that transfers the stored calculation results and controls the memory and the calculation section; and an auxiliary storage device that stores the transferred data of the data compression storage means; The image data digitized by the VD conversion means is sequentially stored in the memory of the data compression storage means, and based on this stored image data, the arithmetic unit calculates the data of the subtractive image, and further calculates a glimpse of the subtractive image. The data of the difference image is obtained by sequentially calculating the value of the difference between the pixels at the position of . By storing data, the data storage capacity is kept to the minimum necessary capacity, and by data compression, the capacity of each frame of image data is reduced, making it possible to send a large number of frames of image data in a short time even at low transfer speeds. In this way, a large number of frames of image data can be stored with an inexpensive system, and this can be done in a short time.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the device of the present invention. In the figure, 1 is an A/D that converts an analog signal into a digital signal.
It is a converter that receives a video signal as image data as a hexagonal signal and converts this into digital image data. 2 temporarily stores the image data converted and outputted by this A/D converter 1 in sequence, and also provides difference data between the image data for the next one screen with respect to the image data for the previous one screen. A data compression/storage device 3 is an auxiliary storage device, such as a magnetic disk device, that stores the compressed data output from the data compression/storage device 2.

FIG. 2 is a block diagram showing a specific configuration of the data compression/storage device 2. In the figure, 21°, 22, 23, and 24 each have a capacity for one screen (one frame), for example, 512 pixels x 512 pixels x It is a semiconductor memory with a memory capacity of 8 bits (gradation), and is used to temporarily store the digital signals sent from the A/D converter 1 and to store the results obtained by the arithmetic circuit described later. fulfill the role of

25 is an arithmetic circuit, and the four semiconductor memories 21.
After subtracting the data on two of ~24 (two frames) for each corresponding pixel, calculate the difference with the subtraction result of the previous pixel (left neighbor) (i.e. , a subtraction image, and a difference image).

Reference numeral 26 denotes a control device that controls the entire data compression and storage device 2, and controls the storage location of the data from the A/D converter 1, the selection and designation of the semiconductor memory to be processed by the arithmetic circuit 25, and the timing control. It performs control, etc. 27 is a pass line through which these data and control signals pass.

Next, the operation of this apparatus having the above configuration will be explained. For example, a video signal of an image captured by an X-ray television device (not shown) is input to the A/D converter 1, where the video signal is converted at a sampling time corresponding to one pixel when one screen is divided into 512 x 512 pixels. The data is converted into digital data with a gradation corresponding to the level, and is input to the data compression/storage device 2 as image data.

Upon receiving the image data, the data compression/storage device 2 sequentially stores the image data in one of the semiconductor memories 21 to 24 under the control of the control device 26. and,
- Once the frame worth of image data is stored, it is sent next and the image data is stored in another semiconductor memory.

Now, the semiconductor memories 21e to 24 are sequentially A and B.

C and D are attached to distinguish them, and the image data sent is sequentially divided into the above A, B, and C in frame units.

Assuming that semiconductor memories D, A, B, C, and D are selected and stored, image data is stored in semiconductor memories 2 and 1 labeled A in the first frame, as shown in Figure 3 (,). memories are made.

Then, in the next frame, image data is stored in the semiconductor memory 2-2 designated as B, and furthermore, in the next frame, image data is stored in the semiconductor memory 23 designated as C.

This device calculates the difference value of the subtractive Sonon image of the image data of the next frame based on the image data of the first frame.
- Since a method of data compression is used to find the difference, at the time when the image data is stored in the semiconductor memory 21 A, there is no image 1 data for the next frame yet, so at this point the difference value is I don't ask for

Next, at the time when the image data is stored in the semiconductor memory 22 designated as B, the calculation of the difference value is not performed. Transfer to.

Next, when image data is stored in the semiconductor memory 23 designated as C, as shown in FIG. 3(b), the semiconductor memory 2 designated as A
The arithmetic circuit 25 calculates the value of the difference between 1 and B in the semiconductor memory 22 for each corresponding pixel position to obtain subtraction image data. The difference values are sequentially determined, and the data of the determined difference values is stored in the semiconductor memory 21 A, whose contents have already been transferred to the magnetic disk device 3 - times.

At the time when image data is stored in the semiconductor memory 24 designated as D, the previously stored semiconductor memories 22.2 and 24 are designated as B and C.
Based on the data of 3, the arithmetic circuit 25 calculates the data of the subtract image for each corresponding pixel position.Furthermore, from this data, the arithmetic circuit 25 calculates the difference value for the adjacent pixel position on the left. The difference value in the subtraction image of the image data of the A and B semiconductor memories 21 and 22 stored in the semiconductor memory 21 A is read out and transferred to the magnetic disk device 3.

This completes the transfer of the data stored in the semiconductor memory 21 designated by A. Since the semiconductor memory 21 designated by this person is now free, the A/D
Image data sent from the converter 1 is stored in a semiconductor memory 21 designated as A. At this time, the arithmetic circuit 25 obtains subtraction image data of the image data of the semiconductor memos IJ 2 J and 24 named C and D for each corresponding pixel position, and furthermore, the arithmetic circuit 25 calculates the subtraction image data of the image data of the semiconductor notes IJ 2 J and 24 to the left of the subtraction image data. The difference values of the data at the pixel positions are sequentially determined and stored in the semiconductor memory 23 (Ic), and the previously determined difference values between the image data of the semiconductor memories (B and C) 220 are read out from the semiconductor memory 22 (B) and are stored in the semiconductor memory 23 (Ic). Transfer to @3.

This completes the transfer of the data stored in the semiconductor memory 22 B. Since the semiconductor memory 22 B is now free, the A/D
The image data sent from the converter 1 is stored in a semiconductor memory 22 called B. At this time, the arithmetic circuit 25 calculates the value of the difference between the image data of the semiconductor memories 24 and 21 called D and A' for each corresponding pixel position to obtain subtraction image data, and further based on this subtraction image data, The difference value of the data at the pixel position is determined by the operation η circuit 25 and stored in the semiconductor memory 24 designated as D. At the same time, the difference value f of the subtraction image data of the previously determined image data of the semiconductor memories 23 and 24 designated as C and D is determined. :C is read out from the semiconductor memory 23 and transferred to the magnetic disk device 3.

As a result, the transfer of the data stored in the semiconductor memory 23 C is completed, and the semiconductor memory 23 C becomes free, so that the next image data sent from the A/D converter 1 is transferred to C.
fr is stored in the semiconductor memory 23.

In this way, frame image data is stored in the four semiconductor memories in order, and during that time, calculations are performed between the stored frame image data that require calculation of subtraction image data, and among the obtained data, , find the difference value of the data at the previous pixel position, store the result in the C semiconductor memory that is not displayed among the semiconductor memories that store all the image data used in this calculation, and save it next. The image data and the difference value saved at the time of image capture are transferred, and the semiconductor memory that saved this difference value is used to store the image data when the next image data is captured. 1 ~ Teyu〈.

As a result, the four sets of semiconductor memories 2 to 24 are used in order to take in image data, store it, calculate it, and send out the results of the calculation. Image data is obtained based on the difference value between each pixel and the previous pixel position in the subtraction image data, which is the difference data.

A subtraction image, which is an image obtained by subtracting data between pixels at corresponding positions in consecutive frames, has large values for areas with movement, but small values for areas with no movement. Become. Therefore, when the target is a heart or the like, when storing continuous time-series digital images, it is possible to save memory capacity by storing subtraction images rather than storing the original images as they are.

In other words, in the case of an organ such as the heart H as shown in Figure FA4, the heart H itself moves, but the surrounding tissue B can be considered to have almost no movement, so in the subtraction image, the pixel of the part with no movement is Since the data such as gradation is the same as the image of the previous frame, the value of the difference itself is extremely small, and the number of pits required for each pixel in this part is small.

Furthermore, when we obtain the difference value (difference image) of the data of each pixel from this subtraction image with respect to the value of the pixel next to the left of the own pixel (the next pixel), we can see that the edge part in the subtraction image has a large value. Other than that, the values are small. Therefore, it is better to store the difference image, and the memory capacity can be further saved than to store the subtract image.

Therefore, this apparatus can significantly reduce the amount of data by storing data in the difference image of the subtraction image.

In addition, the video image signal is temporarily stored while being continuously A/D converted, and on the other hand, the data amount is reduced by calculating the difference image between the collected image data and the subtraction image.
Since this is transferred to the magnetic disk device, the number of frames that can be transferred can be increased even if the transfer speed is low enough to match the magnetic disk device.

For example, in the case of the image in Figure 4 (left ventricle contrast image), the amount of data for at least 778 pixels out of all the pixels can be halved by subtraction operation, and the difference between this image and the adjacent pixel on the left can be It is thought that the amount of data can be further reduced to less than half by performing this operation, so the total amount is (1-7/8・1/2) X 1/2! =;
This means that the amount of data can be reduced by 1/3□.

In addition, in this device, if a method is used to obtain a subtraction image difference image for the entire image, it will take processing time to restore the original image. Use Light Ben etc. to indicate the area on the image display for the monitor, draw a line inside and outside this area between the area where the subtraction image is to be obtained, and the area where the difference image of the subtraction image is to be obtained. The time required for restoring the original image may be shortened by performing the arithmetic processing for each region, or the original image itself may be stored for each predetermined number of patterns to shorten the time required for restoring the image.

In addition, it is possible that the size of the data in areas with movement is considerably larger than other areas, but even in this case, by determining the area and processing it as described above, it is possible to create pits inside and outside the area. The number can be changed, which allows efficient data compression.

[□Effects of invention]

As detailed above, the present invention digitally transforms an image signal.
a memory having storage for a plurality of frames and sequentially storing the digitally converted data and used for calculation and data storage; an arithmetic unit which obtains data of a subtraction image (an image of the difference between pixels at the same position) of the frame to be processed, and obtains data of the difference between each pixel in the subtraction image and the pixel at the partial position of each pixel, and supplies the data to the memory; The data compression storage means is composed of a control section that transfers the stored calculation results and controls the memory and the calculation section, and an auxiliary storage device that stores the transferred data of the data compression storage means. , the image data digitized by the A/D conversion means is sequentially stored in the memory of the data compression storage means, and based on this stored image data, the data of the subtraction image is obtained by the calculation unit, and furthermore, the data of the subtraction image is obtained by Difference image data is obtained by sequentially calculating the difference values between pixels at adjacent positions, and the data is compressed, and all of the compressed data is transferred to a relatively inexpensive and large-capacity auxiliary storage device, such as a magnetic Dinuk device. By storing the data, the total storage capacity is kept to the minimum necessary, and by data compression, the size of image data for each frame is reduced, making it possible to send a large number of frames of image data in a short time even at low transfer speeds. As a result, it is possible to provide an image data collection device having excellent features such as being able to store image data of a large number of frames with an inexpensive system and also being able to do this in a short time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the data compression storage device, and FIG.
The figure is a time chart for explaining the operation of the data compression storage device, and FIG. 4 is a diagram showing an example of an image of a subject. 1... A/D converter, 2... Data compression storage device, 3... Magnetic disk device, 21, 22, 23゜2
4...Memory, 25... Arithmetic circuit, 26-... Control device. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 526 Figure 3 Exclamation Figure 4

Claims (1)

[Scope of Claims] (1) A means for digitally converting an image signal and a memory having a capacity for a plurality of frames, which sequentially temporarily stores the data addressed to the digital data, and which is used for temporary storage of data and temporary storage of calculation results. Based on the digital summer data stored in +7 and the memory, subtraction image data, which is an image of the difference value of □ pixels at the same position in chronologically adjacent 7v-m, is obtained. Consists of an arithmetic unit that calculates the difference data between each pixel and nine pixels and provides it to the memory, and a control unit that transfers the stored arithmetic results and controls the memory and the arithmetic unit. □ An image data collection device comprising a data compression storage means and an auxiliary storage device for storing transfer data of the data compression storage means. -(2)
Data compression using the data compression storage means roughly divides the image into areas with movement and areas with little movement, depending on the state of the image, and in areas with little movement, only subtraction image data is obtained. Tr to make it! jm and 1? ! i. An image data collection device according to claim 1, □. (3) Data on areas with little movement and areas with movement
The image data acquisition device according to claim 2', characterized in that the number of bits constituting the data is changed for each data area.