JPH11134472A - Image processor, storage medium readable by computer and digital photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promptly correct the deviation of gain based on sensitivity of solid-state photographing device by every pixel of a photographed image by using a correction table according to the solid-state photographing device to be used in a system to use plural X-ray solid-state photographing devices by switching them. SOLUTION: Image data 30 to be obtained by radiating X-ray at a state without a subject to be photographed is stored as a value of a gain table in a storage device 39. Storage of the image data 30 is performed for each of plural solid-state photographing devices. And one of the plural gain tables stored according to the solid-state photographing device to be used is read and written in the gain table 45. And the subject is placed, the X-ray is radiated by placing the subject to be photographed and the gain of the image data 30 of the subject to be obtained is corrected by using the gain table 45 in a computing element 33.

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, a computer-readable storage medium, and a digital imaging apparatus suitable for use in an X-ray digital imaging apparatus using a solid-state imaging device.

[0002]

2. Description of the Related Art A film screen system combining an intensifying screen and an X-ray photographic film is often used for X-ray photography for medical diagnosis. According to this method,
The X-rays that have passed through the subject contain internal information of the subject, which is converted into visible light in proportion to the intensity of the X-rays by the intensifying screen, exposing the X-ray photographic film, and forming an X-ray image on the film I do. Recently, an X-ray digital imaging device that converts X-rays into visible light in proportion to the intensity of the X-rays using a phosphor, converts the converted light into an electric signal using a photoelectric conversion element, and converts the converted signal into a digital signal has been used. It is starting to be done. Some of the photoelectric conversion elements use amorphous silicon, and a two-dimensional sensor is configured by arranging the photoelectric conversion elements in a matrix.

[0003] Each photoelectric conversion element of the two-dimensional sensor forms one pixel, but since the sensitivity (gain) of the photoelectric conversion element differs for each pixel, it is necessary to correct this sensitivity difference. Also, since X-rays are output radially from the X-ray generator,
The X-ray intensity incident on the pixel differs depending on the location. As these correction methods, X-rays are emitted without placing the subject in front of the image capturing apparatus, and the maximum pixel value is set to 1 from the image obtained at that time, and the gain corresponding to the image size obtained by normalizing other pixels is set. Make a table. Then, X with the subject placed
Each pixel value of the line image is divided by a value corresponding to each pixel of the above gain table. As an actual method, a method of calculating a photographed X-ray image by software by a CPU and a method of FIG.
As shown in FIG.

In FIG. 4, a gain table 11 in an image capturing device 10 is controlled by a controller 12, and first, an X-ray is irradiated without placing a subject in a state where a buffer 13 is enabled to write data. To get the image. The image data is input from the image input line 14. This image data is LOG-converted through a look-up table 15 for LIN / LOG conversion,
The data is written into the gain table 11 as the gain value G through the buffer 13. Next, in a state where the buffer 13 is invalidated, the subject is placed and irradiated with X-rays to obtain a subject image. The image data input from the image input line 14 is LOG-converted through the look-up table 15,
The data is input to the arithmetic unit 16.

[0005] The controller 12 transmits the X-ray image to the computing unit 1.
Gain table 1 at the same timing as input to
1 is read, and the read data is input to the arithmetic unit 16. The arithmetic unit 16 performs a pixel-by-pixel subtraction between the gain value G from the gain table 11 and the subject image. The output of the arithmetic unit 16 is LIN-converted through a look-up table 17 for LOG / LIN conversion, and is output from the interface 18 as a corrected image.

Here, if G is the gain value of the gain table output and X is the pixel value of the subject image, the look-up table 17 contains log (G / X) = logG-log
A table for converting X into X / G * C is written. That is, C * (10 to the power of −i) (i is an input value to the look-up table 17 = log (G / X))
Becomes At this time, C is a constant determined in advance so that X / G is an integer of 1 or more. For example, if the maximum value of the gain value G is at most 12 bits, C = 2 <12> 4096.

Next, some of the photoelectric conversion elements that do not function normally (defective pixels) exist due to manufacturing problems. It is difficult to manufacture a solid-state imaging device having no defective pixels with the current technology. Normally, a defective pixel is interpolated by inferring it from surrounding pixels and the like. In practice,
There are a method of calculating the captured X-ray image by software using a CPU, and a method of performing the calculation by hardware as shown in FIG.

In FIG. 5, a defective pixel table 21 in an image capturing device 20 is controlled by a controller 22. First, the buffer 23 is written to write data.
With X is enabled, an image is obtained by exposing X-rays without placing a subject. The image data is the image input line 2
4 is input. The defect determination unit 25 determines that the value of the input image data is a certain value or less as a defective pixel,
“1” is written to the defective pixel table 21 via the buffer 23, a pixel having a certain value or more is determined as a normal pixel, and “0” is written to the defective pixel table 21. At this time, the input image data is directly input to the arithmetic unit 26.

Next, with the buffer 23 invalidated,
An X-ray is emitted while placing the subject, and a subject image is obtained.
The image data input from the image input line 24 passes through the defect determination unit 25 as it is and is input to the calculator 26.
The controller 22 reads the defective pixel table 21 at the same timing as the subject image is input to the arithmetic unit 26, and the read data D is input to the arithmetic unit 26. When the defective pixel table value D is “1”, the arithmetic unit 26 invalidates the defective pixel, interpolates the defective pixel by using the immediately preceding pixel, and outputs the corrected image via the interface 27 as a corrected image. .

[0010]

However, the resolution and size of the solid-state imaging device have been improved day by day.
The number of pixels of 000 × 2000 or more has come out, and the total number of pixels has reached 4 M pixels or more. Therefore, when calculating the gain correction by software, it takes a certain amount of processing time. It was a bottleneck for immediate display. In addition, it is conceivable that an X-ray sensor unit including two or more solid-state imaging devices is connected and these X-ray sensor units are switched and used. It was difficult due to the necessity of exposing the rays. That is, in the hardware correction method described above, in order to write a gain value in the gain table 11, the number of X-ray irradiation circuits must be increased. The above has the same problem with the defective pixel table.

[0011]

In an image processing apparatus according to the present invention, a correction means for correcting input image data using a correction table, a storage means for storing the correction table, and a storage means for storing the correction table And control means for reading the correction table and controlling the correction table.

In another image processing apparatus according to the present invention, a correction means for correcting input image data using a correction table, a storage means for storing the correction table, and the correction means connected to the storage means A general-purpose bus means for rewriting the correction table and a control means for controlling the reading of the stored correction table and giving the correction table to the correction table are provided.

In a computer readable storage medium according to the present invention, a procedure for storing a correction table, a procedure for reading out the stored correction table and providing the same to a correction means, and a step for converting input image data into the correction means And a program for executing the procedure of performing correction using the correction table.

In another computer readable storage medium according to the present invention, a procedure for storing a correction table in a storage means, a procedure for reading the stored correction table and providing the correction table to the correction means, A program for executing a procedure of correcting data using the correction table of the correction means and a procedure of rewriting the correction table of the storage means through a general-purpose bus is stored.

Still another computer-readable storage medium according to the present invention stores a correction table for correcting image data.

The digital photographing apparatus according to the present invention has a solid-state imaging device, and the image capturing device has a correction table necessary for correcting an image obtained from the solid-state imaging device. Is connected to a general-purpose bus, can write arbitrary data from a processing device connected to the general-purpose bus, and is connected to a controller that reads the correction table for correcting the image.

[0017]

FIG. 3 is a diagram showing an embodiment of an X-ray imaging apparatus using the present invention. In FIG. 3, the X-rays output from the X-ray generator 1 pass through the subject 2 and enter the X-ray sensor unit 3 attached to the gantry 9. The incident X-ray contains the internal information of the subject 2, and is converted into visible light proportional to the intensity of the X-ray by the phosphor 5 of the solid-state imaging device 4 inside the X-ray sensor unit 3, and the photoelectric conversion is performed. The device 6 converts the charge into a charge proportional to the visible light. Then, the data is digitized by AD conversion and transferred to the control unit 7. Here, the AD conversion may be performed inside the X-ray sensor unit 3 or may be performed by the control unit 7. The transferred image data is displayed on the display unit 8. The control unit 7 is connected to an imaging unit composed of 101 to 106 and 109 similar to the above units 1 to 6 and 9, and can switch imaging.

FIG. 1 shows a first embodiment of the control unit 7, and relates to the above-described gain correction. In FIG. 1, the X-ray sensor unit 3 or 1 shown in FIG.
The image data 30 transferred from the image processor 03 enters the image capturing device 31 and passes through the general-purpose bus interface IF 37 through the lookup table 32 for LIN / LOG conversion, the arithmetic unit 33, the buffer 34, the lookup table 35, and the buffer 36. CPU 38 as a processing device via
Is transferred to and stored in a storage device 39 managed by the user.

To obtain the gain value G, first, C
The PU 38 invalidates the buffer 34, validates the buffer 40, sets the data direction of the buffer 36 to α, and stores the LIN / LI in the lookup table 35 so that the data passes through.
Write the N conversion table. At this time, the controller 41
Is a control signal LUT for the lookup table 35
Generate 0_cont. Next, the CPU 38 sets the buffer 34 to be valid, the buffer 40 to be invalid, the data direction of the buffer 36 to be β, and the arithmetic unit 33 to pass data through.

Then, X-rays are emitted without placing the subject to obtain an image. The image data 30 is LOG-converted through a look-up table 32, and an arithmetic unit 33, a buffer 34, a look-up table 35, a buffer 36
Is transferred to the storage device 39 managed by the CPU 38 via the general-purpose bus interface IF 37 and stored as a gain value. Next, the CPU 38 writes the obtained gain value in the gain table 45, with the buffer 42 being invalid, the buffer 43 being valid, and the data direction of the buffer 44 being α. At this time, the controller 41 generates a control signal TBL_cont for the gain table 45.

Next, the buffer 34 is invalidated, and the buffer 40
Is valid, the data direction of the buffer 36 is α, and the look-up table 35 shows C * (−i of 10) shown in the conventional example.
(I is the input value to the lookup table 35 = 1)
og (G / X)). Then, buffers 34 and 42 are enabled, and buffer 4
0 and 43 are invalid, and the data direction of the buffers 36 and 44 is β
The arithmetic unit 33 is set so that a pixel-by-pixel subtraction between the gain table output and the subject image is performed.

Next, the subject is placed and irradiated with X-rays to obtain a subject image. The image data 30 is LOG-converted through a look-up table 32 and input to a calculator 33. The controller 41 determines that the subject image is
Gain table 45 at the same timing as
Is read, and the read data is input to the arithmetic unit 33. In the arithmetic unit 33, subtraction for each pixel is performed between the gain table output and the subject image. The output of the arithmetic unit 33 is subjected to LIN conversion through a look-up table 35, output as a corrected image, transferred to a storage device 39 managed by a CPU 38 via a general-purpose bus interface IF 37, and stored.

As described above, all the gain tables of the plurality of connected X-ray sensor units 3 and 103 are previously acquired in the storage device 39, and each time the X-ray sensor units 3 and 103 are changed, the gain table is obtained. Writing is performed from the storage device 39 to the gain table 45 in accordance with the X-ray sensor unit.

The ROM 62 and the storage device 56 in FIG. 1 constitute a storage medium according to the present invention. That is, R
The OM 62 stores a program for executing the above-described processing procedure, and the storage device 56 stores a plurality of gain tables. These storage media include a semiconductor memory, an optical disk, a magneto-optical disk,
A magnetic medium or the like is used.

Next, a second embodiment relating to a defective pixel table will be described. Here, it is assumed that the X-ray image is captured as shown in FIG. 3 as in the first embodiment. FIG. 2 shows a second embodiment of the control unit 7 of FIG. 2, image data 50 transferred from the X-ray sensor unit 3 or 103 in FIG.
After entering the image capturing device 51, the arithmetic unit 52, the buffer 5
3, the data is transferred to a storage device 56 managed by a CPU 55 as a processing device via a general-purpose bus interface 54 and stored.

In order to obtain a defective pixel determination bit,
First, the CPU 55 validates the buffer 53,
7, the data direction is set to α, and the arithmetic unit 52 is set so that the data passes through. Then, X-rays are emitted without placing the subject to obtain image data 50, and the image data 50 is passed through the arithmetic unit 52 and the buffer 53 to the general-purpose bus interface IF5.
4 and transferred to and stored in the storage device 56 managed by the CPU 55.

Then, the CPU 55 determines a pixel having a value less than a certain value as a defective pixel from the data. To “0” in the storage device 5
6 is stored. When the determination is completed for all the pixels, the buffers 58 and 53 are disabled, the buffer 57 is enabled, the data direction of the buffer 57 is set to α, and the completed defective pixel table is written to the defective pixel table 60. At this time, a control signal TBL_cont for the controller defective pixel table 60 is generated. And buffer 5
3, 58 valid, buffers 57, 59 invalid, arithmetic unit 5
2 is set so that defective pixel interpolation is performed.

Next, the subject is placed and X-rays are emitted, and the subject image data 50 is input to a calculator 52. The controller 61 reads the defective pixel table 60 at the same timing as the subject image is input to the arithmetic unit 52, and the read data is input to the arithmetic unit 52. When the defective pixel table value = 1, the arithmetic unit 52 determines that the pixel is invalid, interpolates the defective pixel by using the immediately previous pixel, and transfers the defective pixel to the storage device 56 via the general-purpose bus interface IF 54. Will be saved.

As described above, all the defective pixel tables of the plurality of connected X-ray sensor units 3 and 103 are previously acquired in the storage device 56, and each time the X-ray sensor unit is changed, the defective pixel table is obtained. 60 is written. Note that R in FIG.
The OM 62 and the storage device 56 constitute a storage medium according to the present invention, similarly to the ROM 46 and the storage device 39 in FIG.

[0030]

As described above, the gain table,
The defective pixel table is stored in advance and can be rewritten, so that even if the imaging part such as the X-ray sensor unit is replaced, the stored gain value and defective pixel table value can be written to quickly respond. it can. In particular, in the case of X-ray imaging, even if the X-ray sensor unit is replaced, it is possible to cope without exposing X-rays.

Further, the above rewriting can be performed by a processing device through a general-purpose bus.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing an embodiment of the entire X-ray imaging system according to the present invention.

FIG. 4 is a block diagram showing a conventional example.

FIG. 5 is a block diagram showing another conventional example.

[Explanation of symbols]

 1, 101 X-ray generator 2, 102 subject 3, 103 X-ray sensor 4, 104 solid-state imaging device 5, 105 phosphor 6, 106 photoelectric conversion device 7, 107 control unit 30, 50 image data 31, 51 image capture Devices 32, 35 Look-up tables 33, 52 Arithmetic units 38, 55 Processing devices (CPU) 39, 56 Storage devices 41, 61 Controllers 46, 62 ROM

Claims (15)

[Claims] 1. A correction means for correcting input image data using a correction table, a storage means for storing the correction table, and a control for reading out the stored correction table and giving it to the correction means. An image processing apparatus comprising: 2. A correction means for correcting input image data using a correction table, a storage means for storing the correction table, and a general-purpose memory connected to the storage means for rewriting the correction table. An image processing apparatus comprising: a bus unit; and a control unit that reads out the stored correction table and controls the correction table. 3. The image processing apparatus according to claim 1, wherein the correction table is for correcting a gain characteristic between pixels in an image pickup apparatus for obtaining the image data. 4. The image processing apparatus according to claim 1, wherein the correction table is for correcting a pixel defect in an imaging device for obtaining the image data. 5. The storage unit stores a plurality of correction tables corresponding to a plurality of imaging devices selectively used for obtaining the image data, and the control unit stores the plurality of correction tables in the selected imaging device. 3. The image processing apparatus according to claim 1, wherein a corresponding correction table is selected and read from the storage unit. 6. A procedure for storing a correction table, a procedure for reading out the stored correction table and providing the same to a correction means, and a procedure for correcting input image data using the correction table of the correction means. And a computer-readable storage medium storing a program for executing the program. 7. A procedure for storing a correction table in a storage means, a procedure for reading out the stored correction table and providing it to the correction means, and a step of converting the input image data into the correction table of the correction means. A computer-readable storage medium storing a program for executing a procedure for performing correction and a procedure for rewriting a correction table of the storage unit through a general-purpose bus. 8. A computer-readable storage medium storing a correction table for correcting image data. 9. The storage device according to claim 6, wherein the stored correction tables are a plurality of correction tables corresponding to a plurality of image pickup devices for obtaining the image data.
Or the computer-readable storage medium according to 8. 10. The apparatus according to claim 6, wherein the correction table is for correcting a gain characteristic between pixels in an image pickup apparatus for obtaining the image data.
9. The computer-readable storage medium according to 7 or 8. 11. The computer-readable storage according to claim 6, wherein the correction table is for correcting a pixel defect in an imaging device for obtaining the image data. Medium. 12. A digital photographing apparatus having a solid-state imaging device, the image capturing device has a correction table necessary for correcting an image obtained from the solid-state imaging device, and the correction table is connected to a general-purpose bus. Digital photographing apparatus, wherein arbitrary data can be written from a processing device connected to the general-purpose bus, and connected to a controller that reads the correction table for correcting the image. apparatus. 13. The digital photographing apparatus according to claim 12, wherein said solid-state imaging device is sensitive to X-rays, and an image obtained from said solid-state imaging device is an X-ray image. 14. The digital photographing apparatus according to claim 12, wherein the correction table is for correcting a gain characteristic between pixels of the solid-state imaging device. 15. The digital photographing apparatus according to claim 12, wherein the correction table is for correcting a pixel defect of the solid-state imaging device.