JP3041102B2 - 3D image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly to a three-dimensional image processing apparatus.

[0002]

2. Description of the Related Art X-ray CT apparatuses, nuclear magnetic resonance CT apparatuses (M
RI) etc. as a method of creating a three-dimensional image from images
A voxel method of binarizing image data and creating distance data is often used. Here, the binarization means, for example, setting an upper limit area and a lower limit area with respect to data such as a CT value, and “1” when the data is within the area and “0” when the data is outside the area.
In the voxel method, as shown in FIG. 6, a set of binarized data 62 of each slice image 61 as one cube 63 is called voxel data, and when the cube 63 is viewed from outside. , The value “1” is 3
It becomes the surface of the two-dimensional image. Then, in order to obtain a three-dimensional image having a perspective, the distance between the projection plane 64 and the cube 63 is measured, and the data is shaded to obtain a three-dimensional image.

As one of the distance measurement methods, as shown in FIG. 7, a cube 6 is projected from a two-dimensional projection plane 64 outside a cube 63.
There is ray casting that draws a perpendicular line (ray) 65 on 3 and knows the presence or absence of a bit (bit) of each voxel on this perpendicular line (whether the value of the bit is “1”) to measure the distance. In ray casting, ray 65 is projected onto projection surface 64
The data is extended by a unit length from a certain voxel data to a certain voxel data, and the data there is checked. If there is data, the length up to that is the distance data. At this time, since the check of the voxel data needs to be performed only in the area of the voxel data, the data is regarded as “0” in the area outside the area. To regard the area outside the voxel data as “0”, place the voxel data on a large memory,
There is a method in which the area outside the area is always set to "0" or the area is determined and a minimum necessary memory is used. In the method (1), the loss of the memory is large, and the time loss of zero clearing of the memory is large.

[0004]

In the ray scan method,
How far the ray 65 should be extended from the projection plane 64 can be determined by (1) checking the voxel only in the area, (2) stopping the ray 65 when it exceeds the maximum length of the ray, and (3) setting bit "1" in the area. "If it stops, it is determined by the three conditions,
If these three are to be performed by a processing member, for example, a general-purpose CPU (central processing unit), a DSP (digital signal processing unit), or a dedicated arithmetic unit, there is a disadvantage that software overhead increases. .

In the method of checking the above process (c) and inputting a status or an interrupt condition to a processing member such as a CPU, a loss of 2 to 3 steps occurs. For such a CPU, there is an inconvenience that an overhead for performing a conditional branch based on an external condition occurs, and a check time for each point increases.

An object of the present invention is to provide a three-dimensional image processing apparatus capable of realizing three-dimensional image processing with little overhead on software and hardware when generating distance data by binarizing image data. Aim.

[0007]

Therefore, an image processing apparatus according to the present invention uses a three-dimensional image data having a voxel structure and outputs a desired voxel data from a projection plane set at a predetermined position. In a three-dimensional image processing apparatus for measuring a distance to data and performing shading in accordance with the distance to obtain a three-dimensional image, the presence or absence of voxel data having bits in the three-dimensional image data is recognized. Bit check means for holding the status as a status;
Length counting means for drawing a perpendicular line to the two-dimensional image data and measuring a count value corresponding to the distance from the projection plane to the voxel data having bits held by the bit checking means; The means is counted in the perpendicular direction and the status held in the bit check means is checked at predetermined timings. When this status is detected, the counting operation in the perpendicular is terminated , and The perpendicular is three-dimensional
Characterized in that it comprises a stop that control means an operation to extend the image.

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

According to the image processing apparatus of the present invention, at the time of measuring the distance of each perpendicular line in the three-dimensional image processing, the status of the presence / absence of voxel data of the bit check means is checked at predetermined timings. Since the counting operation by the length counter means is controlled by the control means, the processing members such as the CPU and the DSP do not need the judgment processing therefor, and can perform the pipeline operation. Further, since processing members such as the CPU and the DSP can read the output data of the length counter and determine whether or not to end by checking the status, the overhead of the determination processing is reduced.

[0014]

[0015]

[0016]

FIG. 1 is a block diagram showing an example of the structure of a main part of a three-dimensional image processing apparatus having a length counter according to the present invention as a processing member having a calculation unit (not shown). The CPU 1 and the address bus 2 and the data bus 3 connected to the CPU 1 and the distance between the voxel data 63 and the projection plane 64 are measured based on the slice image data input to the address bus 2 and the data bus 3. The length counter 4 is shown. In the present invention, the processing member 1 is not limited to a general-purpose CPU, but may be a general-purpose DSP (DIGITAL SIGNAL PROCESSOR;
Digital signal computing device) or dedicated CPU, DS
P or an arithmetic unit (for example, an arithmetic unit using a bit slice method) may be used.

The length counter 4 receives the slice image data 64 from the image memory and measures the distance by the ray scan method. Therefore, the CPU 1 does not need a judgment process for this, and can perform a pipeline operation. Also, CP
U1 reads the output data of the length counter, and determines whether or not to end by checking the status.

Further, since the length counter 4 operates independently of the CPU 1, the CPU 1 can perform other processing while the length counter is operating. In addition, the CPU 1 has special software for operating the length counter 4.
No code or instructions required.

[Embodiment 1] FIG. 2 is a block diagram showing a configuration of a main part of an embodiment of a three-dimensional image processing apparatus according to the present invention. Memory 7 as a storage device connected to
2 shows a configuration in which an address decoder 5 connected to the address bus 2 and the length counter 4 and a buffer 6 connected to the address decoder 5 and the data bus 3 are connected. Then, the address decoder 5 selects one of the addresses of the CPU 1 and the length counter 4 and outputs the selected address to the buffer 12, and the length counter 4 inputs the slice image data 64 of the image memory 7 and performs ray casting. The distance is counted (measured) and the result is output to the data bus 3.

[Embodiment 2] FIG. 3 is a block diagram showing a first embodiment of a length counter 4 according to the present invention, wherein a mask encoder 41 as an encoder connected to the data bus 3 and a mask encoder 41 are shown. A bit checker 42 as a comparator connected to the data bus 3 and a counter (counter) 43 connected to the bit checker 42 and the data bus 3 and an area determination status input line connected to the bit checker 42 are illustrated.

In FIG. 3, for example, when input data is binarized and compressed to 16 bits or 32 bits (1 bit / 1 pixcel), the mask encoder 41 stores a necessary position in the compressed data. The indicated mask data is set.

The bit checker 42 is a mask encoder 4
The bit of the output data of 1 and the bit of the output data of the image memory 7 are checked. At this time, if the status of the area determination is input, the bit checker 42 checks bits only in the area (if this status is unnecessary, it may not be used).

As shown in FIG. 8, the bit checker 42 outputs the mask data (FIG. 8A) compressed to, for example, 32 bits (FIG. 8A) input from the data bus 3 to the mask encoder 41 and the image memory output. AND with the data format (FIG. 8C), and the result (“1”)
OR “0”) and the input status (FIG. 8D) that takes the value “1” inside the area and the value “0” outside the area, and creates a count condition (bit check output) (FIG. 8E).

The counter 43 is cleared to zero by the CPU 1 at the beginning of the process, and counts up each time image data is input to the length data 4. The condition for stopping the counter 43 is when the output of the bit checker 42 is first turned ON.

The outputs of the length counter 4 are the "result status" of the bit checker 42 (the status in which it is held once even if it is turned ON) and the output of the counter 43. This counter value becomes a distance counter. CPU1
Reads the output data of the length counter 4 and checks the status to determine whether or not the distance measurement has been completed. If the CPU 1 checks the status every cycle as in the conventional method, the overhead increases. However, in the present invention, the length counter 4 operates independently of the CPU 1 and the CPU 1 checks this status every fixed cycle. Other processing can be performed.

For example, if the status check is performed once in 32 cycles and one status check has an overhead of 3 cycles, then (32 + 3)
/32=1.09, which means that the CPU 1 can process with about 10% overhead. In this example, the position of the status bit of the length counter 4 is the MSB (most significant bit; see the output data format of the length counter shown in FIG. 9). In this case, the CPU 1 can know the end of the counter by checking the sign of the input count (length count output). The count value can be easily obtained by masking this status bit (FIG. 10).

[Embodiment 3] FIG. 4 is a block diagram showing a second embodiment of the length counter according to the present invention.
A binarizing member 46 connected to the length counter 4 of the first embodiment via the data bus 3 is shown. The binarizing member 46 includes an upper limit register 461 and a lower limit register 46.
2 and a comparator 463, each of which is connected to the data bus 3, and a status input line 465 is connected to the comparator 463. This embodiment is used when the input data is not binarized. Upper and lower limits are 1
It is used to binarize (digitize) 6-bit or 32-bit volume data. The output of the comparator 463 is "1" within this area, and "0" outside the area.

In this embodiment, the binarizing member is constituted by the upper / lower limit registers and the comparator. However, the present invention is not limited to this. By storing the threshold and comparing the input data with the threshold. Any configuration that outputs either of the two values may be used.

[Embodiment 4] FIG. 5 is a block diagram showing a third embodiment of the length counter according to the present invention.
A memory 48 is shown as a storage device in which either the length counter 4 or 10 is connected to the counter 43, the address bus 2, and the data bus 3. In the first and second embodiments of the length counter, the CPU
Although a processing member such as 1 is interposed in the present embodiment, a memory 48 is provided in this embodiment, and distance data (only the counter value) is input to the memory 48 after the length counter is started. As a result, the processing member such as the CPU 1 can allocate time to other processing. The CPU 1 only needs to read the data in the memory 48 of the length counter 20. As the memory 48, a DPRAM, a FIFO, a RAM, or the like may be used, and may be shared with the memory 7.

As described above, in the three-dimensional image processing apparatus, when binarizing image data to generate distance data, the end of the counting operation for each perpendicular line is controlled by the presence or absence of voxel data. Therefore, three-dimensional image processing with little overhead on software and hardware can be realized. The length counter in the three-dimensional image processing apparatus includes a CPU, a DSP,
And the like, operate independently of the processing members such as, so that the overhead of the distance measurement processing is shortened, and the processing members such as the CPU and DSP do not require special software codes or instructions for operating the length counter.

[0031]

As described above, in the distance measurement of the three-dimensional image processing apparatus according to the present invention, when binarizing image data and creating distance data, the status of the bit check means is checked at predetermined timings. Since the distance measurement operation for the ray is terminated, three-dimensional image processing with little overhead on software and hardware can be realized.

[0032]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a main part of a three-dimensional image processing apparatus including a length counter according to the present invention.

FIG. 2 is a block diagram showing a configuration of a main part of an embodiment of a three-dimensional image processing apparatus according to the present invention.

FIG. 3 is a block diagram showing a first embodiment of a length counter 4 according to the present invention.

FIG. 4 is a block diagram showing a second embodiment of the length counter 4 according to the present invention.

FIG. 5 is a block diagram showing a third embodiment of the length counter 4 according to the present invention.

FIG. 6 is a conceptual diagram showing a voxel method.

FIG. 7 is a conceptual diagram illustrating a ray scan method.

FIG. 8 shows an operation example of a length counter.

FIG. 9 shows an example of an output data format of a length counter.

FIG. 10 shows an example of length count output and status.

[Explanation of symbols]

 Reference Signs List 1 CPU (processing member) 2 address bus 3 data bus 4 length counter 5 address decoder 6 buffer 7 image memory (storage device) 41 mask encoder (encoder) 42 bit checker (comparator) 43 counter (counter) 44 area determination Status input line 45 Binarization member

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06T 15/00-15/70

Claims (1)

(57) [Claims] 1. A method for measuring a distance from a projection plane set at a predetermined position to a target voxel data using three-dimensional image data binarized in a voxel structure, and shading according to the distance. A three-dimensional image processing apparatus for obtaining a three-dimensional image by performing the above-mentioned operation. Bit check means for recognizing the presence / absence of bit-containing voxel data in the three-dimensional image data and storing the same as status, 3 from the side
Length counting means for drawing a perpendicular line to the two-dimensional image data and measuring a count value corresponding to the distance from the projection plane to the voxel data having bits held by the bit checking means; The means is counted in the perpendicular direction and the status held in the bit check means is checked at predetermined timings. When this status is detected, the counting operation in the perpendicular is terminated , and The perpendicular is three-dimensional
3-dimensional image processing apparatus characterized by comprising a stopper that control means the operation to extend the image.