JPH06245122A - Image pickup device - Google Patents

Abstract

PURPOSE:To provide desired contrast to a picture by executing automatically gradation conversion. CONSTITUTION:An incident light (a) via a lens 1 is dispersed by a half mirror 2, the one forms its image on a CCD 5 by a lens 3 and the other is given to a refractive lens 4, in which a low frequency component of an incident light (c) is separated and the resulting light forms its image on a CCD 6. The CCD 5 converts the incident light (b) whose image is formed by the lens 3 into an electric signal (d), and the CCD 6 converts the incident light (c) whose image is formed by the refractive lens 4 into an electric signal (e) to provide an output sequentially. A timing generating drive section 7 generates a timing signal to drive the CCDs 5, 6 and to allow the CCDs 5, 6 to simultaneously provide an output of picture element corresponding to the same position. A subtractor 8 subtracts an output signal (e) of the CCD 6 from an output signal (d) of the CCD 5 and an output of the subtractor 8 is given to a gradation converter 10, in which the gradation is converted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray diagnostic apparatus, and more particularly to a CCD camera as an image pickup apparatus for picking up light (image) from a photomultiplier tube.

[0002]

2. Description of the Related Art A DF device (digital fluorography; angiography device), an X-ray TV bed, an X-ray tube, a photomultiplier tube (II; Image Intensifier), an imaging device (for example, a video camera), and a video. X with monitor
In the fluoroscope, the amount of X-rays transmitted is converted into light by a photomultiplier tube, and this is imaged by a video camera and displayed on a video monitor.

As an image pickup device of a conventional video monitor, a device using a vacuum tube called a Sachicon has been often used, but recently, a CCD (Charge Coupled Device) is being used.

The CCD has many advantages as compared with the SATICON, and one of them is that it has a wide dynamic range and is unlikely to cause halation, so that it can be used as a photomultiplier tube without passing through a subject. It is possible to observe the incident portion and the portion that has transmitted through the subject with large attenuation without halation on the same screen.

FIG. 8 shows a conventional example of a video camera using a CCD. In FIG. 8, the light from the photomultiplier tube passes through the lens 81 and forms an image on the CCD 82. The image on the CCD 82 is driven by the timing generation / CCD drive unit 83 and scanned. The intensity of light corresponding to one cell of the CCD 82 is converted into an electric signal and sequentially input to the A / D converter 84. The output of the A / D converter 84 is subjected to gradation conversion by the gradation conversion circuit 85 so as to match the dynamic range of the monitor, and is input to the D / A converter 86 and output as an analog output (also output as a digital output in FIG. 8). It has a configuration that can be).

FIG. 9 shows an example of an X-ray fluoroscope using a CCD video camera. In FIG. 9, the X-ray from the X-ray tube 91 is X.
The dose is controlled by the line generation control unit 92, and the subject P on the bed 93 is exposed. The transmitted X-ray dose transmitted through the subject P is converted into light by the photomultiplier tube and is passed through the optical system (not shown (corresponding to the lens 81 in FIG. 8)) to the CCD camera 95.
To enter.

The CCD camera 95 outputs, for example, an analog signal or a digital signal in the same manner as in the case of FIG. 8 described above. Then, in the case of an analog signal output, it is directly input to the video monitor 96 and displayed as a diagnostic image on the monitor 96.

In the case of digital signal output, for example, the signal is input to the digital image processing device 97, subjected to image processing, D / A converted, and input as an analog signal to the video monitor, and then as a diagnostic image on the monitor. Is displayed in.

As described above, a video camera using such a CCD as an image pickup element has a characteristic that it is hard to cause halation because it has a wide dynamic range. In the above technology, a gradation conversion circuit is provided and the gradation conversion is performed on the digital data after A / D conversion so as to match the dynamic range of the monitor.

[0010]

However, the above-mentioned conventional technique has a problem that if the gradation conversion is performed so as to match the dynamic range of the monitor, the gradation becomes uniform and the screen has no contrast.

For example, even if an image in which a desired contrast is emphasized with respect to the displayed image is to be obtained, such an image cannot be automatically obtained, and a complicated manual operation is required. There is an inconvenience that it is not always possible to obtain a desired contrast.

The present invention has been made in view of the above problems and inconveniences, and in an X-ray diagnostic apparatus, an image pickup apparatus capable of giving a desired contrast to an image by automatically performing an appropriate gradation conversion. It is intended to provide (CCD camera).

[0013]

In order to achieve the above object, the image pickup apparatus of the present invention obtains first and second incident light from incident light and forms an image of the first incident light. An optical system for obtaining an optical image, a first charge-coupled device for converting the optical image into an electric signal to obtain a first electric signal, and a low spatial frequency component of a predetermined spatial frequency or lower from the second incident light are separated. And a second charge-coupled device for converting the low spatial frequency component into an electric signal to obtain a second electric signal, and a synchronization / driving device for synchronizing and driving the first and second charge-coupled devices. Driving means, subtracting means for inputting the first and second electric signals and subtracting the second electric signal from the first electric signal, and gradation for performing gradation conversion on the subtraction result by the subtracting means And a conversion means.

[0014]

With the above arrangement, the image pickup apparatus of the present invention obtains the first and second incident lights from the incident light by the optical system, forms the first incident light to obtain the optical image, and The charge coupled device converts the optical image into an electric signal to obtain a first electric signal, and the optical filter means separates a low spatial frequency component equal to or lower than a predetermined spatial frequency from the second incident light and outputs the low spatial frequency component. The second charge coupled device converts the low spatial frequency component into an electric signal to obtain a second electric signal.

Then, the synchronizing / driving means synchronizes and drives the first and second charge-coupled devices, and the subtracting means inputs the first and second electric signals, and the first and second electric signals are input. The electric signal is subtracted, and the gradation conversion unit performs gradation conversion on the subtraction result of the subtraction unit.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of an embodiment of an image pickup device according to the present invention, which is a CCD as an image pickup device.
The camera converts an optical image formed by the lens 3 into an electric signal d, and an optical system including a lens 1 that converges the incident light a, a half mirror 2 that disperses the incident light a that has passed through the lens 1, and a lens 3. A CCD 5 that sequentially outputs the birefringent lens 4 and a CCD 6 that converts the optical image formed by the birefringent lens 4 into an electric signal e and sequentially outputs the electric signal e.
It has a timing generating / driving unit 7 for driving the CCD 5 and the CCD 6 synchronously, a subtractor 8, and a gradation converting unit composed of a coefficient K input unit 9 and a gradation converter 10.

In FIG. 1, the incident light a is converged by the lens 1 and is incident on the half mirror 2 and is dispersed by the half mirror 2. One of them is transmitted through the half mirror 2 and is incident on the lens 3, and the CCD 5 is transmitted by the lens 3. Image on top. The other one is reflected by the half mirror 2 and enters the birefringent lens 4. Incident light (optical image) that has passed through the refractive lens 4
Is a light component that is low-pass filtered in terms of spatial frequency, so that the low-frequency component of the incident light c (which means the light with the lower spatial frequency) is separated by the birefringent lens 4 and the low-frequency component is An image is formed on the CCD 6.

The CCD 5 converts the incident light b imaged by the lens 3 into an electric signal d and sequentially outputs it (C in FIG. 2).
An example of an image obtained from the output of CD5 is shown in FIG.
The profile about the part of the line segment A on the image of FIG.

Further, the CCD 6 converts the incident light c imaged by the refractive lens 4 into an electric signal e and sequentially outputs the electric signal e (for the portion corresponding to the line segment A in FIG. 2 on the low-pass image in FIG. 5). Shows the profile). In this case CC
Since D6 handles images whose spatial frequencies are not too high, C
An element having a lower spatial resolution than CD5 may be used.

The timing generating / driving unit 7 generates a timing signal to drive the CCD 5 and CCD 6 in synchronism with each other so that the pixels corresponding to the same position are simultaneously output from the CCD 5 and CCD 6.

The subtracter 8 inputs the output signals d and e from the CCD 5 and CCD 6, and outputs the CC from the output signal d of the CCD 5.
The output signal e of D6 is subtracted. At this time, the output signal e of the CCD 6 is multiplied by K by the coefficient K input by the coefficient K input means. The output of the subtractor 8 is input to the gradation converter 10.

The gradation converter 10 performs conversion as shown in FIG. 7, for example, and outputs a gradation-converted signal. Here, FIG. 3 is an example of an image obtained from the output of the gradation converter 10, and is an image obtained by gradation conversion by subtracting a low-pass image from the image shown in FIG. Further, FIG. 4 is a profile for a portion of the line segment B on the image of FIG.

Therefore, according to the present invention, it is possible to suppress halation and perform gradation conversion with contrast. In the above embodiment, the subtractor, the gradation converter, etc. can be realized by using an operational amplifier or the like. Also CCD
The above subtracter, gradation converter, etc. can be realized by converting the output from the above into digital data and using digital circuit technology. The embodiment of the present invention has been described above.
It is needless to say that the present invention is not limited to the above embodiment and various modifications can be made.

[0024]

As described above, according to the CCD camera of the present invention, an image signal which does not cause halation by proper gradation conversion, has contrast, and does not cause frame delay of the screen is sent to the monitor. You can Further, since it is possible to provide an image with contrast, the density resolution of the image is improved. Further, since the resolution of the image is improved, an image that can be more easily inspected is provided, which can contribute to the improvement of diagnostic efficiency by shortening the inspection time.

For example, when the image pickup apparatus of the present invention is used as an image pickup apparatus (CCD camera) of an X-ray diagnostic apparatus as shown in FIG. 9, an image in which halation is suppressed can be observed even in contrast imaging of the lower limbs. Therefore, in order to suppress halation, it is possible to save labor such as inserting an X-ray compensation filter in the crotch, which has been conventionally performed, and to reduce the burden on the operator.

Similarly, in the PTCA method (percutaneous angioplasty) or the like, it is possible to observe an easily visible image with contrast in which the halation of the lung field is suppressed, and the operation of the catheter is facilitated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an image pickup device (CCD camera) according to the present invention.

FIG. 2 is an example of an image obtained from the output of a first charge coupled device (CCD).

FIG. 3 is an example of an image obtained from the output of the gradation converter 10.

FIG. 4 is a profile for a portion of a line segment A on the image of FIG.

5 is a profile of a portion corresponding to the line segment A in FIG. 2 on the low-pass image.

6 is a profile for a portion of a line segment C on the image of FIG.

FIG. 7 is an explanatory diagram of gradation conversion by a gradation converter.

FIG. 8 is a conventional example of a video camera using a CCD.

FIG. 9 is an example of an X-ray fluoroscope using a CCD video camera.

[Explanation of symbols]

 1, 3 Lens (Optical System) 2 Half Mirror (Optical System) 4 Birefringent Lens (Optical Filter Means) 5 CCD (First Charge Coupled Device) 6 CCD (Second Charge Coupled Device) 7 Timing Generation / Drive Part 8 Subtractor 9 Coefficient K input means 10 Gradation converter (gradation conversion means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 5/66 A 9068-5C

Claims (1)

[Claims] 1. An optical system that obtains first and second incident light from incident light and forms an optical image by forming an image of the first incident light; and an optical system that converts the optical image into an electric signal. 1st to get the signal of 1
Charge-coupled device, optical filter means for separating and outputting low spatial frequency components below a predetermined spatial frequency from the second incident light, and converting the low spatial frequency component into an electric signal to generate a second signal. A second charge-coupled device to be obtained, a synchronization / driving means for synchronizing and driving the first and second charge-coupled devices, the first and second signals, and the second signal from the first signal An image pickup apparatus comprising: a subtracting unit that subtracts the signal of 1. and a gradation converting unit that performs gradation conversion on the subtraction result of the subtracting unit.