JPH01160526A - Electronic endoscopic apparatus - Google Patents

Abstract

PURPOSE:To obtain a sharp image easy to observe, by a method wherein two kinds of bright and dark images taken by the irradiation with two kinds of strong and weak lights different in intensity of radiation emitted from an irradiation means are held to an image memory and a part in a saturated part is replaced with image data, which is corrected by utilizing the dark image, on the basis of the bright image by an operation means. CONSTITUTION:The image signal synchronous to the lighting of a light source lamp, that is, the image signal taken using strong irradiation light and an image signal taken using weak irradiation light are alternately outputted from a CCU 9 to be digitalized by an A/D converter 10 and subsequently changed alternately by a change-over part 11 to be respectively stored in and held to a bright image frame memory FM 12 and a dark image frame memory FM 13. When halation is generated in the bright image data taken by the illumination due to the pulse like lighting of usual intensity being strong irradiation light, the region in a saturated state of the bright image data held to the FM 12 is replaced with the data, which is corrected by adding the difference between both image data to the data of the corresponding region of the dark image data held to the FM 13, by an operation part 14.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to an electronic endoscope device, and more specifically, the present invention relates to an electronic endoscope device, and more specifically, it relates to an electronic endoscope device, and more specifically, to prevent halation, etc. due to an excessive amount of light in an endoscopic image, or black images due to an insufficient amount of light in an endoscopic image. An electronic endoscope device is used to remove debris and provide an easy-to-see image.

(Prior art) An endoscope is introduced into the inside of an inspection target such as a device, a VJ structure, a human body, etc., and the subject is imaged by a small CCD camera built into the tip of the electronic endoscope. The display range of the brightness and darkness of the screen is limited by the dynamic range of a CCD camera using a non-life element such as a CCD.

However, due to the limited dynamic range of a CCD camera, it may not be possible to obtain a desired image of a subject.

When the CCD camera is introduced into the object to be inspected and illuminated with illumination light while photographing, the amount of light incident on the CCD camera is too high for objects that are close to the object, and is likely to cause halation, while the amount of light is insufficient if the object is far away. This results in an image that is dark and difficult to discern details, and black spots may appear especially in areas where there is a severe lack of light.

(Problems to be Solved by the Invention) As described above, in the conventional CCD camera, the dynamic range was not very wide and was limited, and therefore the amount of light was likely to be excessive or insufficient.

Too much or too little light can cause halation or black spots.

The area where halation occurs becomes pure white and loses color information, similar to black whelks.

When such a phenomenon occurs, the value of the endoscopic image obtained after being introduced into the interior of the object to be examined is greatly reduced.

This invention was made in consideration of these conventional problems, and it compensates for the lack of dynamic range of CCD cameras, and eliminates the problems caused by halation, black spots, etc.
The object of the present invention is to provide an electronic endoscope device that can obtain clear, easy-to-see images.

[Structure of the Invention (Means for Solving Problems)] In order to achieve the above object, an irradiation means capable of alternately irradiating two types of light intensity of light, strong and weak, at a predetermined timing, and this irradiation means are provided. Using an image memory that can hold two types of image data, bright and dark, captured with two types of light intensity, and the two types of images held in this image memory, the brighter image is captured. The area where halation, etc. is occurring is detected, and the detected area is corrected by adding the difference between both images (image data) to the image data of the darker image corresponding to this area. He devised a calculation means to replace the data, and an electronic endoscopy device.

(Function) According to the electronic endoscope device having such a configuration, there are two
Two types of bright and dark images captured by irradiation with an irradiation means having different amounts of light are stored in an image memory,
Based on the brighter image, the calculation means can replace saturated portions such as halation with image data corrected using the darker image.

In this way, it is possible to correct halation and the like, so that images can be taken using irradiated light with a sufficient amount of light without producing dark, black spots or the like. For areas where saturation has occurred, by correcting and replacing data from a relatively dark image with a reduced amount of irradiation light, we can create an image with a wide range of color information without losing any color information. It becomes possible to provide

(Embodiment) FIG. 1 shows a block diagram of the main parts of an electronic endoscope apparatus according to an embodiment of the present invention.

In this invention, two types of bright and dark images are obtained using irradiated light of two types of intensity and weak, and correction etc. are performed. As the irradiation light, two types of irradiation light, strong and weak, are used, each of which has a weaker emission intensity and has the same width.

Furthermore, although the configuration has been made such that photographing and compensation using these two types of irradiation light are carried out at all times, for example, it may be made to be carried out only when a freeze switch that requests a still image is turned on. .

In this example, 1 is used as the imaging probe of the CCD camera.
A single-plate frequency interleaved CCD whose frame is composed of ODD-EVEH 2'z-rules is used.

In FIG. 1, inside the endoscope body 6, there is a control section 1 that controls each part of this device, including a freeze switch 3 that notifies the control section 1 of a freeze request, and a freeze switch 3 that notifies the control section 1 of a freeze request, and a freeze switch 3 that controls normal irradiation according to instructions from the control section 1. There is a light source unit 2 that switches between two types of irradiation light, strong and weak, and introduces the irradiation light from one end of a light guide (not shown) provided through the endoscope 8.

Then, the above-mentioned light guide (not shown) is installed, and the object is irradiated with light from the other end, and the light reflected from the object is captured by the installed CCD camera (not shown). There is an endoscope 8 that is sent to the main body 6.

The endoscope main body 6 further receives the original image signal and receives the above-mentioned original image signal.
For example, a camera control unit (hereinafter abbreviated as CCU) 9 that converts into a video signal such as an NTSC signal;
An A/DIO converts the analog image signal from the CCU 9 into digital image data, and an image frame memory (hereinafter referred to as FM )-
12 and 13, and the control unit 1 is connected to these FM12 and 13.
a switching unit 11 that switches and transfers image data according to instructions from
There is. A calculation unit 14 is provided that detects a portion of a bright image that causes halation, extracts image data of the corresponding portion from a dark image, corrects it, and replaces it, and stores the corrected image resulting from the calculation. FM1
5, and a D/A 16 that converts this image again into an analog video signal in order to display it on a display unit 17 such as a color monitor.
There is. On the other hand, a diagonal interface (I/F) 4 is also provided for sending the corrected image data held in the FM 15 to an external storage device 5 or the like.

FIG. 2 is a diagram showing the detailed internal structure of the light source section 2 of the electronic endoscope device of this embodiment.

For example, a lamp 21 as an illumination light source using a xenon lamp or the like.
There is a mirror 22 that reflects the light emitted from the lamp 21 and focuses it toward the left in FIG. 2, and a condenser lens 23 that focuses the thus collected light onto one end of the light guide 24.
There is. Then, in response to the instruction from the control unit 1, the lamp 2
There is a lamp drive power supply 25 that varies the power supply to the lamp 1 to promote pulsed light emission of intensity and weakness.

Next, the operation of this embodiment of the apparatus will be explained based on the drawings.

FIGS. 3 and 4 are diagrams showing the relationship between the timing of imaging and the timing of emitting light.

According to instructions from the control unit 1, the rung drive power source 25 changes the strength of the lamp 21 as shown in the lower part of FIG. Repeats the pulsed lighting.

For example, when images are being taken at a camera shooting rate of 60 fields per second (normal rate), as shown in Fig. (reverse) lighting is repeated depending on the amount of light.

Furthermore, if the rate is twice the normal rate, that is, 120 fields per second, the intensity of lighting may be repeated for each frame as shown in FIG.

In FIG. 1, a COD camera (not shown) disposed on the rigid portion at the tip of the endoscope 8 is controlled by a CCU 9.

The CCU 9 alternately outputs an image signal synchronized with the lighting of the light source lamp 21 shown in FIG.
/D conversion After being digitized by the Mi10, they are alternately switched by the switching unit 11 and stored and retained in the frame memory FM12 for bright images caused by strong irradiation light, and the frame memory FM13 for dark images caused by weak irradiation light. be done.

FIGS. 8 to 13 are explanatory diagrams of the essential operations of the present invention, which correct and replace a saturated area using the two types of images described above.

In each of these explanatory diagrams, only one type of image memory is shown as an operation example.9 For example, R (red), G (green), B
If the device has frame memories (FM) for each of the three colors (blue), similar processing such as correction may be performed for each of them.

In addition, the resolution of the image data held in each FM is expressed as 8-bit data from 0 to 255 in digital values.

When halation as shown by the black circles in Figure 8 occurs in bright image data taken with illumination by pulsed lighting with normal intensity, which is strong irradiation light, the bright image data stored in FM12 in Figure 8 As shown in Figure 9, in the area corresponding to the horizontal scanning line indicated by
55).

At this time, consecutively! ! Dark image data caused by weak irradiation light that is shaded and held in the FM 13 is saturated even at its peak, as shown in Figure 10, because the light emission intensity is appropriately controlled by the control unit 1 so that the output signal does not become saturated. has not been reached.

Next, in the arithmetic unit 14, an area where the bright image data held in the FM 12 is in a saturated state (X in FIG.
1 to X2> are replaced by data corrected by adding the difference between both image data to the data in the corresponding area (X1 to X2 in FIG. 1O) of the dark image data held in the FM 13.

In other words, the saturated region in FIG. 9, X1 to Add and correct the difference. This can be calculated, for example, by multiplying the value of the weak image data by the reciprocal of the ratio of the light amounts of the strong and weak irradiation lights. The data thus obtained is replaced with each data in the area X1 to x2 in FIG. Detection, correction, and replacement are performed in this way.

The image data thus obtained is shown in FIG.

In this example device, the corrected image data having a wide data change range obtained in this way is converted in accordance with a predetermined conversion function in the calculation unit 14, and the change range of the original data (0 to 255 ) and then stored in the FM 15 and displayed as an image on the display unit 17 via the D/A 16.
Alternatively, it is configured to output to an external storage device or the like 5 via the I/F 4.

This conversion process will be explained based on FIGS. 11 to 13.

The image data as shown in FIG.
It is converted according to the conversion function shown in the figure. That is, when the data value in FIG. 11 is input, the amplification factor is set to 1 when the input value is less than the value a in FIG. 12, and is set to be less than 1 when the input value is greater than the value a. The value of a and the amplification factor for input values of 8 or more are set so that the output value is not saturated. Such a conversion function allows amplification and
The converted output data is as shown in Fig. 13, and while the signal output in the part where halation etc. occurs decreases,
The signals in the dark areas are converted without deterioration.

By performing this conversion, it is possible to suppress the brightness of extremely bright areas without losing signal information, and to obtain output image data that maintains sufficient brightness for very bright areas. Since the depth of the image data, that is, the numerical value and focus width of the image data are the same as the original image data, it is possible to easily handle the image data after correction and conversion processing.

Next, the timing of image reading in this embodiment apparatus will be explained.

If the image capture rate of the CCD camera is 60 fields per second, like a normal TV signal, as shown in Fig. ) Each image is taken with weak illumination in the field. and calculation section 14
When displaying an image corrected by 1. Assume that the same image is displayed in consecutive even and odd fields.

Furthermore, if you use a CCD camera with an imaging rate of 120 fields per second, which is twice the frequency of a normal TV signal, as shown in Figure 71, a strong irradiation light will appear in the n-th frame. An image with weak irradiation light is taken in the n+1th frame, and a corrected image is formed from the two consecutive frame images. In this case, since the corrected image can be obtained based on the frame image data, a decrease in screen resolution can be prevented.

Further, as a second embodiment, a case of an electronic endoscope using a color camera of a frame sequential method will be described.

In a field-sequential color camera, for example, a disc-shaped RGBB color filter is provided between a white light source and a light guide light kite and rotated to emit irradiation light of each color of R-G, B. The photos will be taken one after another. At this time, in synchronization with the rotation of the color filter, the light source unit 2 is configured to generate strong irradiation light in the n-th R-G-B cycle and weak irradiation light in the n±1-th cycle. The present invention can be applied by controlling the lighting of the.

Further, FIGS. 5 to 7 are explanatory diagrams showing third and fourth embodiments of the present invention.

The third embodiment is a different configuration example in which the present invention is applied to an electronic endoscope using a frequency interleaved single-plate CCD camera, as in the first embodiment.

To explain its configuration with reference to FIG. 5, the light source section 2 of the endoscope includes a lamp 21 using, for example, a xenon lamp, and the light emitted from this lamp 21 is reflected and focused on the left side of FIG. There is a mirror 22 that focuses the light thus collected onto one fly of the light 1 to the guide 24.

A rotary filter plate 26 that adjusts the amount of light transmitted through the two types of filters and a motor 27 that rotates the plate at a constant angular velocity are provided.

FIG. 6 is a diagram showing an example of the structure of the rotating filter plate 26. An empty transmission window 261 and an neutral density (ND) filter 262, which has a predetermined light attenuation rate and does not change the spectral composition of light, are provided point-symmetrically across the center of rotation. ing.

When the rotary filter plate 26 is rotated once in the direction of the arrow in FIG. 6 by the motor 27, pulsed irradiation light of varying strength is generated.

By using the two types of strong and weak irradiation light obtained in this way, the same processing as in each of the above-mentioned embodiments is performed, thereby making it possible to obtain the same effects as on each of the above-mentioned sides.

Further, FIG. 7 shows an electronic endoscopy system using the same frame-sequential color camera as in the second embodiment, with a configuration roughly similar to that of the third embodiment shown in FIGS. 5 and 6. This figure shows a fourth embodiment in which the present invention is applied to a mirror.

In the case of the field sequential method, the light from the light source is converted into R, G, and B color light using a rotating filter and illuminated.
After each B image is photographed separately, these three types of images are superimposed to form a color image.

Therefore, by attaching RlG and B color filters having two types of transmittance to the rotating filter of the light source, it is possible to easily obtain irradiated light with two types of light amounts, strong and weak.

In this way, it becomes possible to correct for halation and the like in the same manner as in the embodiment apparatus using the single-chip color camera described above.

FIG. 7 shows an example of a rotating filter when such a frame sequential color camera is used.

In FIG. 7, R1, G1, B1, and R2, G2
, B2 are R, G, and B color filters, respectively;
R1, G1, and B1 have higher light transmittance.

Further, the color filters R1 and R2, G1 and G2, and B1 and B2 are arranged so that the ratio of their respective light transmittances is equal.

In this way, both single-chip CCD cameras and frame-sequential color cameras can now take two types of bright and dark images using strong and weak illumination light to correct for halation, etc. Furthermore, the present invention can be realized by electrical control of a light source lamp or by a mechanical method using a rotating filter.

Note that other methods include, for example, preparing two illumination light source lamps and switching between them to emit light, or inserting an ND filter just in front of the camera.

Furthermore, the present invention is not limited to the respective configuration examples and aspects shown in each of the embodiments described above, and the image capturing rate, the shape and rotation speed of the rotating filter, and the number of pulses generated in each rotation may also differ. Of course, it can also be implemented in other aspects.

[Effects of the Invention] As explained above in detail, the electronic endoscope device according to the present invention is configured to obtain and correct both bright and dark images using two types of strong and weak irradiation light. , it is possible to increase the irradiation time to avoid black spots, etc., and even if a saturation state such as halation occurs, it is possible to compensate and replace from the other image, effectively improving the camera's dynamics. You can get the same effect as when the cleanse is expanded,
It becomes possible to provide clear and easy-to-see endoscopic images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of an electronic endoscope device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of its light source section, and FIGS. 3 and 4 are lamp light emission in this embodiment of the device. 5 is a configuration diagram of the light source section of the third and fourth embodiments of the present invention, and FIG. 6 is the shape of the rotating filter in the third embodiment of the present invention. FIG. 7 is an explanatory diagram of the shape of a rotating filter in the fourth embodiment, FIG. 8 is an explanatory diagram of a portion where halation occurs, and FIGS. 9 to 13 are image complementation operations according to the present invention. FIG. 1... Control unit 2... Light source unit 3... Freeze switch 4... I/F 5... External storage device 6
...Endoscope body 8...Scope 9...CCU
10...A/D11...Switching unit 12.13.
15...FM 14...Calculation section 16...D/
A 17...Display section 21...Lamp 22...
・Mirror 23...Condensing lens 24...LG
25...Lamp drive power supply 26...Rotating filter plate 261...No filter 262...ND filter 27...Motor game (J Dojin j? Jl ten near) Kishi Shi Mengr -------1 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 1○ Figure 13

Claims (1)

[Claims] (1) An irradiation means that irradiates the subject by alternately switching at a predetermined timing irradiation light having two types of light intensity, strong and weak, and an image memory that holds two types of image data, bright and dark, obtained by irradiation with this irradiation means. Then, in the bright image data obtained with strong irradiation light stored in this image memory, areas that are saturated due to excessive light intensity are detected, and dark image data obtained with weak irradiation light corresponding to the detected areas are detected. An electronic endoscope apparatus comprising: arithmetic means for correcting a region by adding the difference between the two image data and replacing it with data of the detected region.