JPH0563990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an imaging device, and more particularly to an improvement in an imaging device that images a subject having a wide range of luminance from low luminance to high luminance.

Description of Prior Art In general, imaging devices that use image pickup tubes, solid-state image sensors, etc. are equipped with the following techniques: to prevent damage such as burn-in caused by strong light, or to obtain images with appropriate brightness.
Equipped with an AGC (automatic sensitivity control) circuit. Incidentally, depending on the object to be imaged, there may be a mixture of high-luminance parts and low-luminance parts, and the difference between them may be very large. For example, when observing a biological organ using reflected light from a light source, since the surface is wet, the image of the light source may be reflected from the surface and formed on the image pickup tube or image sensor. In this case, a state occurs in which the part where the image of the light source is formed by the reflected light has extremely high brightness, and the other parts of interest are dark.
In such a state, when the AGC circuit is activated, the AGC is applied to representative areas of high brightness, making the area of interest increasingly darker, making it difficult to observe in detail.

On the other hand, if the sensitivity (applied voltage) of the image pickup device is increased by canceling the AGC circuit, a problem arises in that the image pickup element in the portion where the amount of incident light is large will cause so-called burn-in phenomenon and be destroyed.

In order to solve the above-mentioned drawbacks or problems, a light transmittance changing means such as a liquid crystal element is placed between the subject and the image pickup tube, and the light transmittance changing means such as a liquid crystal element is arranged between the subject and the image pickup tube to It is conceivable to designate a region and reduce the light transmittance of the light transmittance changing means in the designated portion. According to such an imaging device, it is possible to reduce the amount of incident light in a portion with high brightness, thereby preventing burn-in of the imaging means. However, the image information obtained by such an imaging device cannot be said to be faithful to the actual subject because the brightness is partially adjusted. However, when performing image measurement using a computer or the like, image information that is faithful to the actual subject is required. Therefore, such an imaging device has a new problem in that the target range of image measurement or image measurement may be significantly limited.

Purpose of the Invention The present invention provides the ability to sufficiently increase the brightness of the part to be observed and observe it in detail without causing the burn-in described above, even when imaging an object with a mixture of high and low brightness parts. The aim is to provide an imaging device that can

Another object of the present invention is to provide an imaging device that can obtain image information that is faithful to a real subject.

Configuration and Effects of the Invention To summarize, the present invention includes an imaging means that receives reflected light from an object and outputs an image of the object formed on an imaging surface as image information, and a communication between the object and the imaging means. A light transmittance changing means capable of changing the light transmittance of an arbitrary area on the light transmitting surface of the optical system provided between the two, and a light transmittance changing means capable of changing the light transmittance of an arbitrary region on the light transmitting surface of the optical system, and a brightness of the image of the subject imaged by the imaging means to a predetermined reference level. Compared to,
means for specifying a region with high brightness in the subject image based on the comparison result; A control means for controlling the transmittance changing means to reduce the transmittance, and a means for storing image information output from the imaging means are provided, and the image information corresponding to the aforementioned specified area stored in the storage means is provided. means for performing arithmetic processing on the above-mentioned light transmittance determined in advance and restoring the stored image information to image information equivalent to the state in which the above-mentioned control means is not operating. It is.

According to this invention, if only a high-luminance part is specified in a limited manner based on the above-mentioned comparison result in the image of the subject captured by the imaging means, the control means adjusts the luminance of that part to a predetermined level. Therefore, the sensitivity of the imaging device can be increased without causing burn-in of the imaging device. Therefore, the user can sufficiently increase the brightness of the part of the object image that he or she wants to observe without worrying about burn-in, and can obtain a clear image.

Further, according to the present invention, the image information stored in the storage means is processed using the restoring means based on the above-mentioned light transmittance that is predetermined for the image information corresponding to the above-mentioned specified area. ,
It is possible to restore the image information equivalent to the state in which the control means is not operating, and to restore the image information about the subject image to image information that is faithful to the original image. Therefore, the observation range in which image measurement and image measurement can be performed can be greatly expanded. For example, measuring changes in the metabolic dynamics of pigment proteins such as heme proteins in living tissues, or
This invention produces particularly useful effects in the measurement of a wide range of light intensity from weak light to flash light, such as fluorescence measurement of natural fluorescent substances such as NADH and quenching fluorescence measurement. Light intensity measurement can be performed without damaging the imaging means and with simple operation.

Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a schematic block diagram showing one embodiment of the present invention. In the figure, a living organ (hereinafter referred to as a living body) 1, which is an example of a subject, is illuminated with illumination light from above by an illumination device 3 having a power supply device 2. This reflected light from the living body 1 is transmitted through the objective lens 5.
The light is focused by the microscope 4 and magnified by the microscope 4.
The image magnified by this microscope 4 is transmitted through an optical fiber 8 to an imaging tube 6, which is an example of imaging means. Note that a liquid crystal element 7 is provided on the imaging surface of the microscope 4.
is placed. Therefore, the optical fiber 8 transmits the image passed through the liquid crystal element 7 to the image pickup tube 6. Note that a solid-state image sensor may be used instead of the image pickup tube 6. Further, a lens system may be used instead of the optical fiber 8. Here, the liquid crystal element 7 is divided into a plurality of regions as shown in FIG. 3, which will be described later, and it is possible to change the light transmittance for each region.

The output of the image pickup tube 6 is given to an amplifier circuit 9. This amplifier circuit 9 is configured so that its amplification factor can be changed by manual operation from the outside. The output of the amplifier circuit 9 is given to an A/D conversion circuit 10, and the analog pixel signal is converted into a digital signal. The output of the A/D conversion circuit 10 is written into the image storage circuit 12 by the write circuit 11. The image of the subject stored in the image storage circuit 12 is read out by a readout circuit 13 and provided to a D/A conversion circuit 14. This D/A conversion circuit 14 converts the digital signal back into an analog video signal and provides it to a monitor television 15. Therefore, the image of the subject is displayed on the monitor television 15.

The control circuit 17 is constituted by a so-called microcomputer or the like, and controls the operations of the above-mentioned image pickup tube 6, write circuit 11, and read circuit 13.
Further, an input device 16 is connected to this control circuit 17 . This input device 16 includes means for manually specifying a portion of high brightness in the image of the subject displayed on the monitor television 15. As such a specifying means, a keyboard, a light pen, a digitizer, etc. are used. moreover,
The input device 16 includes means for inputting various information to the control circuit 17. Further, an output device 21 is connected to the control circuit 17 . This output device 2
1 includes, for example, a printer, and the input device 1
The disease name, date, patient name, etc. input from 6 are output. Further, a liquid crystal control circuit 18 is connected to the control circuit 17 . This liquid crystal control circuit 18 is
Although not shown, it includes a memory that stores information on which region of the liquid crystal element 7 should have its light transmittance reduced. As described above, the liquid crystal element 7 is divided into a plurality of regions as shown in FIG. 3, and the light transmittance can be changed for each region. The memory included in the liquid crystal control circuit 18 has storage areas corresponding to a plurality of areas of the liquid crystal element 7 as shown in FIG. Store in the corresponding address. Furthermore, although not shown, the liquid crystal control circuit 18 includes a readout circuit for sequentially reading out information from the above-mentioned memory, and the output of this readout circuit is given to the driver 19. The driver 19 drives the liquid crystal element 7 according to information given from the liquid crystal control circuit 18. Further, information read from the memory included in the liquid crystal control circuit 18 is given to the arithmetic circuit 20. This arithmetic circuit 20 is for arithmetic processing of the image information stored in the image storage circuit 12 so as to restore the corrected image of the subject in the high brightness portion to the original image.

FIG. 2 is a graph showing applied voltage-light transmittance characteristics of the liquid crystal element 7. FIG. 3 is a diagram schematically showing the state of the light transmittance of the liquid crystal element 7 after correction of the high brightness portion. Below, these figures 2 and 3
The operation of the embodiment shown in FIG. 1 will be explained with reference to the drawings.

An image of the living body 1 is magnified by a microscope 4 and then formed on an image sensor 6 via a liquid crystal element 7 and an optical fiber 8 to be imaged. The output of the image pickup tube 6 is applied to an amplifier circuit 9, where it is amplified with an appropriate degree of amplification, and then applied to an A/D conversion circuit 10, where it is converted into a digital signal. The output of the A/D conversion circuit 10 is given to a write circuit 11 and written to an image storage circuit 12. The image information of the subject written in the image storage circuit 12 is read out by the readout circuit 13 and provided to the D/A conversion circuit 14 . The D/A conversion circuit 14 converts the digital image information into an analog video signal and provides it to the monitor television 15. Therefore, the image of the living body 1 is displayed on the monitor television 15.

Here, on the monitor television 15, so that each divided area of the liquid crystal element 7 can be visually recognized,
For example, grids as shown by dotted lines in FIG. 3 are displayed together with the image of the subject. Note that the squares indicated by dotted lines in FIG. 3 are added for convenience to clarify that the liquid crystal element 7 is divided into a plurality of regions whose light transmittance can be individually changed. Such a dotted line is not attached to the actual liquid crystal element 7. An operator or an observer looks at this monitor television 15 and searches for a portion of high brightness that may cause image pickup tube 6 to burn. If there is a portion with high brightness that would cause burn-in, information specifying that portion is input from the input device 16 to the control circuit 17. Information specifying this high brightness area is input manually using, for example, a light pen, a keyboard, a digitizer, or the like. For example, in the case of a light pen, this is done by touching a square in a high brightness area on the display screen of the monitor television 15 with the light pen. Further, an address is assigned in advance to each square on the display screen of the monitor television 15, and this address is input by key operation on the keyboard. Also, this is performed by displaying a cursor on the monitor television 15 and moving the cursor to a square with high brightness by operating keys on the keyboard. The control circuit 17 writes information input from the input device 16 specifying the high brightness portion into a memory included in the liquid crystal control circuit 18 . The information written in this memory is read out by a readout circuit included in the liquid crystal control circuit 18 and then given to the driver 19. The driver 19 increases the voltage applied to the corresponding area of the liquid crystal element 7 in accordance with information given from the liquid crystal control circuit 18 . Second
As shown in the figure, as the applied voltage increases, the light transmittance of the liquid crystal element 7 decreases. Therefore, in the liquid crystal element 7, the light transmittance of the area corresponding to the portion specified by the operation of the input device 16 is reduced, for example, as shown by diagonal lines in FIG. The degree to which the light transmittance is reduced at this time is one percentage for each region, and is reduced to, for example, 1/2 of the original light transmittance. As a result, the amount of light in the high-brightness portion is reduced, and image capture on the image pickup tube 6 can be prevented.

On the other hand, when the original image information before correction of the high-brightness portion is required for image measurement by a computer or the like, an image information restoration command is input from the input device 16.
In response, the control circuit 17 activates the arithmetic circuit 20. The arithmetic circuit 20 reads out information specifying a high brightness portion stored in a memory included in the liquid crystal control circuit 18 and reads out image information corresponding thereto from the image storage circuit 12. As mentioned above, the degree to which the light transmittance of the liquid crystal element 7 is reduced is, for example, 1/2.
Since it is determined to be a constant value, the calculation circuit 20
calculates the original brightness by, for example, doubling the brightness of the image information read from the image storage circuit 12. This calculation result is written into the original area of the storage circuit 12. As a result, the image storage circuit 12 stores image information equivalent to the image information before the high-brightness portion is corrected. That is, a portion whose brightness has been corrected to decrease can be restored to its original brightness level. Therefore, image measurement of high-luminance parts is also possible, and the target range in which image measurement can be performed can be expanded.

Note that the liquid crystal element 7 used in the above embodiment includes:
Although various types are commercially available, those having an electric field-controlled birefringence effect or those having a horizontally aligned guest-host effect are easy to use.

Further, in the above-described embodiments, a case where a microscope is equipped with an image pickup tube has been described, but similar effects can be expected when an endoscope is equipped with an image pickup tube, or a fundus camera or the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention. FIG. 2 is a graph showing applied voltage-light transmittance characteristics of the liquid crystal element 7. FIG. 3 is a diagram schematically showing the light transmittance state of the liquid crystal element 7 when the high brightness portion is corrected. In the figure, 1 is a biological organ, 2 is a power source, 3 is a light source, 4 is a microscope, 5 is an objective lens, 6 is an imaging tube,
7 is a liquid crystal element, 8 is an optical fiber, 9 is an amplifier circuit,
10 is an A/D conversion circuit, 11 is a write circuit, 12 is an image storage circuit, 13 is a readout circuit, 14 is a D/A conversion circuit, 15 is a monitor television, 16 is an input device,
17 is a control circuit, 18 is a liquid crystal control circuit, 19 is a driver, 20 is an arithmetic circuit, and 21 is an output device.

Claims (1)

[Scope of Claims] 1. Imaging means for inputting reflected light from a subject and outputting a subject image formed on an imaging plane as image information; and storing image information output from the imaging means. means, an optical system provided between the subject and the imaging means for making the reflected light incident and forming the subject image on the imaging surface; and an optical system provided in relation to the optical system. , a light transmittance changing means for changing the light transmittance of an arbitrary region on the reflected light transmitting surface of the optical system, and comparing the brightness of the subject image with a predetermined reference level, and comparing the brightness of the subject image with a predetermined reference level, means for specifying a region with high brightness in the subject image based on the above; and adjusting the light transmittance of a region on the transmission surface corresponding to the region specified by the specifying means to a predetermined light transmittance. a control means for controlling the light transmittance changing means to reduce the light transmittance; and a control means for calculating the image information stored in the storage means corresponding to the designated area based on the predetermined light transmittance, An imaging device comprising means for returning to image information equivalent to a state in which the means is not activated. 2. The imaging device according to claim 1, wherein the designation means includes means for performing the designation by manual operation.