JP2002034908A - Endoscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate and visually recognize tissue information of a desired deep tissue near a tissue surface of an organism tissue. SOLUTION: An image processing circuit 30 comprises respective three sets of LUTs 62a to 62c, and 63a to 63c before and after a 3×3 matrix circuit 61, and a coefficient changing circuit 64 for converting coefficients of table data of each LUT and the 3×3 matrix circuit 61, and forms a color conversion processing circuit 30a. Regarding RGB(red, green, blue) data to be inputted to the color conversion processing circuit 30a, inverse γ correction, nonlinear contrast conversion, or the like is performed in a front stage of LUTs, the color conversion is performed by the 3×3 matrix circuit 61, and then γ correction or an adequate gradation conversion process is performed in a rear stage of LUTs. Change by the coefficient changing circuit 64 is based on a control signal from a mode exchanging circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope apparatus for capturing an image of a living tissue and processing the signal.

[0002]

2. Description of the Related Art Conventionally, an endoscope apparatus which irradiates illumination light to obtain an endoscopic image in a body cavity has been widely used. In this type of endoscope device, an electronic endoscope having imaging means for guiding illumination light from a light source device into a body cavity by using a light guide or the like and capturing an image of a subject by return light is used, and a video processor is used. An endoscope image is displayed on an observation monitor by performing signal processing on an image pickup signal from the image pickup means, and an observation site such as an affected part is observed.

When ordinary living tissue observation is performed with an endoscope device, a light source device emits white light in the visible light region,
For example, the subject is irradiated with plane-sequential light through a rotation filter such as RGB, and the return light due to the plane-sequential light is synchronized with a video processor to perform image processing, thereby obtaining a color image, A color chip is arranged on the front surface of the imaging surface, and return light by white light is RGB by the color chip.
Then, a color image is obtained by taking an image by separating the image and processing the image with a video processor.

[0004] On the other hand, in living tissue, light absorption and scattering characteristics differ depending on the wavelength of the irradiated light.
For example, various infrared endoscope apparatuses have been proposed that can irradiate a living tissue with infrared light as illumination light and observe a tissue deep in the living tissue.

[0005]

However, in diagnosing a living tissue, deep tissue information near the tissue surface is also an important observation object. However, in the infrared endoscope apparatus described above, a deep portion of the tissue is deeper than the tissue surface. Only organization information can be obtained.

Also, white light is converted into RGB light by a rotation filter.
When a living tissue is irradiated as plane-sequential light, the wavelength range is different. Therefore, the imaging signal by the light of each color has different deep tissue information near the tissue surface of the living tissue. In order to make the endoscope image by the light into a more natural color image in order, the white light is separated into RGB light in which each wavelength region overlaps.

In other words, in the overlapped RGB light, a wide depth of tissue information is captured in an image signal of light in each wavelength range, so that desired deep tissue information near the tissue surface of a living tissue can be visually recognized. Is difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an endoscope apparatus capable of separating and visually recognizing desired deep tissue information near a tissue surface of a living tissue. And

[0009]

An endoscope apparatus according to the present invention comprises:
Illumination light supply means for supplying illumination light including a visible light region,
An endoscope having an imaging unit that irradiates the object with the illumination light and images the object with return light; and an endoscope device including a signal processing unit that performs signal processing on an imaging signal from the imaging unit. A band limiting unit that limits at least one of a plurality of wavelength ranges of the illumination light and forms a band image of a discrete spectral distribution of the subject on the imaging unit from the illumination light supply unit to the imaging unit; A band limiting arrangement unit detachably disposed on an optical path to reach, wherein the signal processing unit changes color processing of the imaging signal according to an arrangement state of the band limiting unit by the band limiting arrangement unit. Is done.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 14 relate to a first embodiment of the present invention. FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus.
2 is a configuration diagram showing the configuration of the rotary filter of FIG. 1, FIG. 3 is a diagram showing spectral characteristics of a first filter set of the rotary filter of FIG. 2, and FIG. 4 is a second filter set of the rotary filter of FIG. FIG. 5 is a diagram showing a layered structure of a living tissue observed by the endoscope apparatus of FIG. 1, and FIG. 6 is a diagram showing a layered direction of living tissue of illumination light from the endoscope apparatus of FIG. FIG. 7 is a view showing each band image by plane-sequential light transmitted through the first set of filters in FIG. 3, and FIG. 8 is a plane sequential transmitted through the second set of filters in FIG. FIG. 9 is a diagram showing each band image by light, FIG. 9 is a diagram for explaining dimming control by the dimming circuit of FIG. 1, FIG. 10 is a configuration diagram showing a configuration of the image processing circuit of FIG. 1, and FIG. FIG. 12 is a diagram showing a color image of the narrow band RGB image obtained by the processing circuit, and FIG. 12 shows a 3 × 3 matrix of FIG. FIG. 13 is a diagram illustrating an example of setting a LUT in FIG. 10, and FIG. 14 is a diagram illustrating a configuration of a modification of the color conversion processing circuit in FIG. 10. FIG.

As shown in FIG. 1, an endoscope apparatus 1 according to the present embodiment includes an electronic endoscope 3 having a CCD 2 as an image pickup means for inserting into a body cavity and imaging tissue in the body cavity, and an electronic endoscope. A light source device 4 for supplying illumination light to the light source 3 and a C of the electronic endoscope 3
A video processor 7 processes an image signal from the CD 2 to display an endoscope image on the observation monitor 5 or encodes the endoscope image and outputs it to the image filing device 6 as a compressed image.

The light source device 4 includes a xenon lamp 11 that emits illumination light, a heat ray cut filter 12 that cuts off heat rays of white light, an aperture device 13 that controls the amount of white light passing through the heat ray cut filter 12, A rotating filter 14 for converting illumination light into a surface-sequential light, a condenser lens 16 for condensing surface-sequential light via the rotating filter 14 on an incident surface of a light guide 15 disposed in the electronic endoscope 3, Rotary filter 1
4 and a control circuit 17 for controlling the rotation.

As shown in FIG. 2, the rotary filter 14
It has a disk-like structure and has a double structure with the center as a rotation axis, and outputs a surface-sequential light having overlapping spectral characteristics suitable for natural color reproduction as shown in FIG. Filter 1 constituting a first set of filters for
4r1, a G1 filter 14g1, and a B1 filter 14b1 are arranged, and a narrow-band plane-sequential light having discrete spectral characteristics from which desired deep tissue information can be extracted as shown in FIG. R2 forming the second filter set of
Filter 14r2, G2 filter 14g2, B2 filter 1
4b2 are arranged. And the rotation filter 14
As shown in FIG. 1, the rotation of the rotary filter motor 18 is controlled by the control circuit 17 and the rotary filter is rotated. The radial movement (movement perpendicular to the optical path of the rotary filter 14, Filter set or second
Is selectively moved on the optical path) by the mode switching motor 19 according to a control signal from a mode switching circuit 42 in the video processor 7 described later.

The xenon lamp 11, the aperture device 1
3. Rotary filter motor 18 and mode switching motor 19
Is supplied with power from the power supply unit 10.

Returning to FIG. 1, the video processor 7
A CCD drive circuit 20 for driving D2, and an objective optical system 21
, An amplifier 22 that amplifies an image signal obtained by imaging the tissue in the body cavity by the CCD 2 via the CCD 2, a process circuit 23 that performs correlated double sampling, noise removal, and the like on the image signal that has passed through the amplifier 22, and a process circuit 23. A / D converter 2 for converting an imaging signal into digital signal image data
4, a white balance circuit 25 for performing white balance processing on image data from the A / D converter 24, a selector 26 for synchronizing plane-sequential light by the rotating filter 14, and synchronizing memories 27a, 27b, 27c. An image processing circuit 30 that reads out image data of plane-sequential light stored in the synchronization memories 27a, 27b, and 27c and performs gamma correction processing, contour enhancement processing, color processing, and the like; D / A to convert to analog signal
Circuits 31a, 31b, 31c and D / A circuits 31a, 3
An encoding circuit 34 for encoding the outputs of 1b and 31c, and a timing generator 35 for inputting a synchronization signal synchronized with the rotation of the rotation filter 14 from the control circuit 17 of the light source device 4 and outputting various timing signals to the respective circuits. And is provided.

The electronic endoscope 2 is provided with a mode changeover switch 41.
1 is a mode switching circuit 42 in the video processor 7
Is output to The mode switching circuit 42 of the video processor 7 outputs a control signal to the dimming circuit 43, the dimming control parameter switching circuit 44, and the mode switching motor 19 of the light source device 4. The dimming control parameter switching circuit 44 outputs a dimming control parameter corresponding to the first filter set or the second filter set of the rotary filter 14 to the dimming circuit 43. Based on the control signal and the dimming control parameter from the dimming control parameter switching circuit 44, the diaphragm device 13 of the light source device 4 is controlled to perform appropriate brightness control.

As shown in FIG. 5, the tissue 51 in the body cavity often has an absorber distribution structure such as blood vessels different in the depth direction. Many capillaries 52 are mainly distributed near the surface layer of the mucous membrane, and in the middle layer deeper than this layer, a blood vessel 53 thicker than the capillaries is distributed in addition to the capillaries, and a thicker blood vessel 54 is further distributed in the deeper layer. become.

On the other hand, the depth of the light in the depth direction of the light with respect to the tissue 51 in the body cavity depends on the wavelength of the light. As shown in FIG. ) In the case of light with a short wavelength such as color, light can only reach the surface layer due to absorption and scattering characteristics in living tissue, and is absorbed and scattered within the range of the depth, and exits from the surface. Light is observed. In the case of green (G) light having a wavelength longer than that of blue (B) light, the light reaches deeper than the range where blue (B) light deepens, and is absorbed and scattered in that range and exits from the surface. Light is observed. Furthermore, red (R) light, which has a longer wavelength than green (G) light, reaches a deeper range.

At the time of normal observation, an R1 filter 14 as a first filter set of the rotary filter 14 is provided on the optical path of the illumination light.
The mode switching circuit in the video processor 7 controls the mode switching motor 19 according to the control signal so as to be located at r1, the G1 filter 14g1, and the B1 filter 14b1.

R1 at the time of normal observation of the tissue 51 in the body cavity
Filter 14r1, G1 filter 14g1, B1 filter 1
4b, as shown in FIG. 3, since the respective wavelength ranges overlap each other, the imaging signal captured by the CCD 4 using the B1 filter 14b1 contains a large amount of tissue information in a shallow layer as shown in FIG. A band image having tissue information including shallow and middle layers is captured, and the C1 image is obtained by the G1 filter 14g1.
As shown in FIG. 7B, a band image having shallow-layer and middle-layer tissue information containing a large amount of tissue information in the middle layer is captured as an image signal captured by the CD4.
FIG. 7 shows an image pickup signal picked up by the CCD 4 by r1.
A band image having middle and deep tissue information including a large amount of tissue information at the deep layer as shown in FIG.

Then, by synchronizing these RGB image pickup signals with the video processor 7 and performing signal processing, it is possible to obtain an endoscope image having a desired or natural color reproduction as an endoscope image.

On the other hand, when the mode changeover switch 41 of the electronic endoscope 3 is pressed, the signal is input to the mode changeover circuit 42 of the video processor 7. Mode switching circuit 42
Outputs a control signal to the mode switching motor 19 of the light source device 4 to move the first filter set of the rotary filter 14 that was on the optical path during normal observation and dispose the second filter set on the optical path. The rotary filter 14 is driven with respect to the optical path as described above.

The R2 filter 14r2, the G2 filter 14g2, and the B2 filter 14b2 at the time of narrow-band light observation of the tissue 51 in the body cavity by the second filter set make the illumination light have a narrow discrete spectral characteristic as shown in FIG. In order to obtain band-sequential light in a sequential manner, a band image having tissue information in a shallow layer as shown in FIG. A band image having tissue information in the middle layer as shown in FIG. 8 (b) is picked up by an image pickup signal picked up by the CCD 4 by the 14g2, and furthermore, a CC image by the R2 filter 14r2 is taken.
A band image having tissue information in a deep layer as illustrated in FIG. 8C is captured in the imaging signal captured in D4.

At this time, as is apparent from FIGS. 3 and 4, the amount of light transmitted by the second set of filters is smaller than the amount of light transmitted by the first set of filters because the band becomes narrower. The control parameter switching circuit 44 outputs a dimming control parameter corresponding to the first filter set or the second filter set of the rotary filter 14 to the dimming circuit 43, so that the dimming circuit 43 controls the diaphragm device 13. Then, as shown in FIG. 9, the aperture device 1 at the time of normal observation according to the set value Lx on a setting panel (not shown) of the video processor 7.
For narrow linear light observation, for example, a linear aperture control line 61 by 3 is used to control the aperture device 13 to control the light amount Mx by an aperture control curve 62 corresponding to the set value Lx. As a result, image data with sufficient brightness can be obtained even during narrowband light observation.

Specifically, in conjunction with the change from the first filter set to the second filter set, the light amount set value Lx
Is changed from Mx1 to Mx2 as shown in FIG. 9, and as a result, the aperture is controlled in the opening direction and the amount of illumination is reduced by narrowing the band of the filter. Operate to compensate.

As shown in FIG. 10, the image processing circuit 30
Represent three sets of LUTs 62a, 62b, 62c, 63a,
63b, 63c and LUTs 62a, 62b, 62c, 6
The color conversion processing circuit 30a includes table data of 3a, 63b, 63c and a coefficient changing circuit 64 for converting coefficients of the 3 × 3 matrix circuit 61.

The RGB data input to the color conversion processing circuit 30a is divided into LUTs 62a, 62b, 6 for each band data.
2c. Here, inverse γ correction, non-linear contrast conversion, and the like are performed.

Next, in a 3 × 3 matrix circuit 61,
After the color conversion is performed, the LUTs 63a, 63b, 6
At 3c, gamma correction and appropriate gradation conversion processing are performed.

These LUTs 62a, 62b, 62c, 6
It can be changed by the coefficient changing circuit 64 which converts the table data of 3a, 63b, 63c and the coefficient of the 3 × 3 matrix circuit 61.

The change by the coefficient changing circuit 64 is based on a control signal from the mode switching circuit 42 or a control signal from a processing conversion switch (not shown) provided in the operation section of the electronic endoscope 3 or the like.

The coefficient changing circuit 63 receiving these control signals
Recalls appropriate data from coefficient data previously written in the image processing circuit 30, and rewrites the current circuit coefficient with this data.

Next, the specific color conversion processing will be described. Equation (1) shows an example of the color conversion equation.

[0034]

(Equation 1) The processing according to the equation (1) is an example of conversion in which the data generated by mixing the B image with G at a certain fixed ratio is used as a new G image. By narrowing the band of the illumination light of each band, it is possible to further clarify that absorption scatterers such as a blood vessel network differ at depth positions.

That is, it is possible to further increase the difference in the information on the biological augmentation reflected by each band by narrowing the band of the illumination light.

When these narrow-band RGB images are observed as color images, the images are as shown in FIG. 11, for example. The thick blood vessel is at a deep position, is reflected in the R band image, and is shown as a blue pattern in color. Since the vascular network near the middle layer is strongly reflected in the G image, it is shown as a red pattern as a color image. Among the vascular networks, those existing near the mucosal surface are expressed as yellowish patterns.

In particular, the change in the pattern near the mucosal surface is important for the early differential diagnosis and differential diagnosis. However, the yellow pattern tends to have low contrast with the background mucous membrane and low visibility.

Therefore, in order to more clearly reproduce the pattern near the mucosal surface, the conversion shown in equation (1) is effective. Equation (1) can be expressed in matrix form as equation (2)
become that way.

[0039]

(Equation 2) Therefore, by adjusting the matrix coefficient through the coefficient changing circuit 64, the user can adjust the display effect. As the operation, the matrix coefficient is set to a default value from the through operation in the image processing means in conjunction with a mode changeover switch (not shown) provided in the operation unit of the electronic endoscope 3.

The "through operation" here means that a unit matrix, LUTs 62a, 62b,
Reference numerals 62c, 63a, 63b, and 63c indicate a state where a non-converted table is mounted. The default value means that the matrix coefficient is given a set value of, for example, ω _G = 0.2 and ω _B = 0.8.

Then, the user operates a processing change switch or the like provided on the operation unit of the electronic endoscope 3, a video processor housing panel, or the like, and sets the coefficients to ω _G = 0.4 and ω _B =
Make adjustments such as 0.6. LUT 62a,
An inverse γ correction table and a γ correction table are applied to 62b, 62c, 63a, 63b and 63c as necessary.

Next, a description will be given of a process of performing color correction in the color conversion processing circuit 30a so as to maintain the average color tone as much as possible even when the filter is switched.

As a result of the filter switching, the spectral characteristic of the illumination light changes. As a result, the color reproduction also changes. Depending on the situation of use and the user, it may be desirable to maintain the average color reproduction as much as possible while maintaining the effect of improving the contrast of the microstructure on the mucous surface. In such a case,
According to the filter switching, the coefficient changing circuit 6 performs a color conversion operation to maintain the average tone from the through operation.
It is necessary to change the operation according to 4.

The procedure for creating a matrix that maintains the average color tone will be described below. As shown in FIG. 12, it is assumed that the color distribution of the subject in the RGB color space moves from the first distribution to the second distribution according to the filter switching. In such a case, at least three points are selected from the first distribution (normally, including distribution average and center-of-gravity data), and it is checked where these three points move in the second distribution. Then, a conversion matrix from the second distribution to the first distribution is calculated by using these three sets of data, and is used as a matrix coefficient of the 3 × 3 matrix circuit 61. Note that three or more points can be selected and determined by the least squares method.

The LUTs 62a, 62b, 62c, 63a,
If inverse γ correction and γ correction tables are set for 63b and 63c as required and the above matrix coefficients are applied,
Even when the filter is switched, it is possible to achieve color reproduction with the average color tone maintained as much as possible.

In particular, by utilizing the fact that the narrow band B image reflects the fine structure of the mucous membrane surface such as a pit pattern well, it is possible to reproduce an image effect such as dye staining only with the B image. That is, out of the RGB data input from the matrix conversion expression shown in Expression (3), only the B data constitutes the output RGB data.

[0047]

(Equation 3)By adjusting the coefficient, the effect like a dye-stained image can be obtained.
Can produce fruit. For example, ω_B>> ω_G, Ω_RSet in
The image will have a bluish hue,
The color tone is similar to that obtained when igo dyeing is performed. Also,
ω_B, Ω_R>> ω _RIf set to, the image will have a purple hue
Thus, an image having a tone of piotanine is obtained. Further
When the LUT settings are set as shown in FIG.
The last becomes a hard reproduction and the control seen in the stained image
An image with a high last can be obtained.

As described above, according to the present embodiment, by setting the parameters of the color conversion processing circuit 30a in conjunction with the switching of the filter, an expression method utilizing the feature of the depth information of the narrow-band RGB illumination light is used. Can be realized, and tissue information at a desired deep portion near the tissue surface of the living tissue can be separated and visually recognized.

In the above-described embodiment, the color conversion processing circuit 30a is shown as having a configuration centered on the 3 × 3 matrix circuit 61. However, as shown in FIG. 14, the color conversion processing circuit 30a corresponds to each band. The same effect can be obtained by replacing with the three-dimensional LUT 71 described above. In this case, the coefficient changing circuit 64 performs an operation of changing the contents of the table based on the control signal from the mode switching circuit 42.

FIGS. 15 to 18 relate to the second embodiment of the present invention. FIG. 15 is a block diagram showing a configuration of an endoscope apparatus, and FIG. 16 is a block diagram showing a configuration of an image processing circuit of FIG. FIG. 17 is a configuration diagram showing the configuration of the color adjustment circuit of FIG. 15,
FIG. 18 is a diagram showing the concept of hue and saturation in the L * a * b * color space in the color adjustment circuit of FIG.

Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

In the present embodiment, color conversion independent of devices such as monitors such as XYZ and color spaces dependent on devices such as RGB are performed as color conversion of a color conversion processing circuit that changes the operation in conjunction with the operation of filter switching. This shows a case where coordinate conversion means is included between.

As shown in FIG. 15, the electronic endoscope 2 is provided with a processing switch instruction switch 81, and the image processing circuit 30
Receives a control signal from the mode switching circuit 42 and an instruction signal from the processing switching instruction switch 81, and performs a color conversion process described later.

As shown in FIG. 16, the color conversion processing circuit 30b included in the image processing circuit 30 includes LUTs 82a, 82b, and 82c provided for each band, a 3 × 3 matrix circuit 83, and a color adjustment circuit. 84, a 3 × 3 matrix circuit 85 at the subsequent stage, and LUTs 86 a, 86 b, 86 c located at the subsequent stage and provided for each band, and a coefficient changing circuit 64.

First, the RGB data input to the preceding LUTs 82a, 82b, 82 are subjected to inverse gamma correction. This is for canceling the nonlinear γ correction performed in consideration of the γ characteristics of the display device such as a CRT before the color conversion processing.

Next, the preceding 3 × 3 matrix circuit 83
XYZ which is a device-independent color space from RGB
Convert to The conversion equation is shown in equation (4). In equation (4), xi, yi, zi (i = R, G, B) are xy chromaticity coordinates of the primary colors of a display device such as a CRT.

[0057]

(Equation 4) Next, after the color adjustment circuit 84 undergoes appropriate color adjustment described later, a 3 × 3 matrix circuit 85 in the subsequent stage uses the expression (5) to re-determine the device-dependent color space R′G ′.
LUT after conversion to B '
Are output to the observation monitor 5.

[0058]

(Equation 5) Next, the operation of the color adjustment circuit 84 will be described. Color adjustment circuit 8
4 is a perceptual color space conversion unit 87 that performs conversion from XYZ to a perceptual color space such as L * a * b *, as shown in FIG.
And hue perceived by humans as three attributes of color, conversion to saturation, and hue for inverting to L * a * b * after adjusting these values intuitively, It is composed of a saturation conversion adjustment unit 88 and a perceived color inverse conversion unit 89 that performs conversion to XYZ again.

Equation (6) shows a conversion equation between L * a * b * and XYZ, and equation (7) shows a conversion equation from L * a * b * to hue Hab and Cab. Here, Xw, Yw, and Zw represent the XYZ values of the reference white.

[0060]

(Equation 6)

(Equation 7) Fig. 1 shows the concept of hue and saturation in the L * a * b * color space.
FIG.

Once converted to hue and saturation,
Color adjustment can be performed intuitively. For example, if you want to make the color tone vivid, multiply the saturation by a certain coefficient or add it to increase the value. If the color is to be changed in the blue or red direction, the hue value may be adjusted. In this manner, intuitive color adjustment can be performed by the color adjustment unit.

Next, the operation in cooperation with the mode switching circuit 42 and the processing switching instruction switch 81 will be described.
The feature when observed with narrow-band RGB illumination light is that, when there are different structures in the depth direction of a living body such as a blood vessel structure, they are represented by different colors. In order to further emphasize this feature, by enhancing the saturation and rotating the hue appropriately, more effective display can be achieved.

Therefore, in conjunction with the mode switching circuit 42, for example, the color is adjusted without performing color adjustment during normal observation, and flows through without performing color adjustment during narrow-band observation, based on an instruction signal from the processing switch instruction switch 81. The coefficient changing circuit 64 changes the coefficient of the related circuit. Further, when observation is performed using the narrow-band RGB illumination light, the degree of saturation enhancement and the degree of hue rotation are switched according to the user's preference, the type of subject, and the like, in accordance with an instruction from the processing switching instruction switch 81.

The conversion from RGB to XYZ is performed by an equation based on a normal CRT device model, but the calculation method of luminance Y in XYZ may be changed as shown in equation (8). In equation (8), when calculating Y, RG
It has been changed so that the ratio of B can be specified.

[0065]

(Equation 8) The narrow band RGB B image has a feature that the fine structure of the surface of the living mucous membrane is reflected with high contrast. In order to reflect this information in the luminance information, it is preferable to increase the weight ω _B of B when calculating Y. In general, since the luminance of B is lower than that of RG (the luminance sensitivity of a human is G at maximum), the information of B is not greatly reflected on the luminance when it is directly calculated by Expression (6). Therefore, it becomes meaningful to adjust the weight of B as described above.

In the narrow-band RGB image, since each band image reflects a different biological structure, the weight can be adjusted according to the purpose of use according to equation (8). Note that a plurality of combinations of weights may be prepared in advance, and may be switched by control from the processing switch. In this case, the inverse conversion from XYZ to RGB uses Expression (7).

As described above, in the present embodiment, similarly to the first embodiment, by setting the parameters of the color conversion processing circuit 30a in conjunction with the filter switching, the narrow band RGB is achieved.
It is possible to realize an expression method utilizing the feature of the depth information of the illumination light, and it is possible to separate and visually recognize tissue information at a desired deep portion near the tissue surface of a living tissue.

19 to 24 relate to the third embodiment of the present invention, FIG. 19 is a configuration diagram showing a configuration of an endoscope apparatus, FIG. 20 is a configuration diagram showing a configuration of a rotary filter of FIG. FIG. 21 shows G2, B2a and B2b of the rotary filter of FIG.
FIG. 22 is a diagram showing the configuration of the band selection circuit of FIG. 19, FIG. 23 is a diagram showing the configuration of a modification of the rotary filter of FIG. 19, and FIG. FIG. 4 is a diagram illustrating spectral transmission characteristics of a rotation filter.

Since the third embodiment is almost the same as the first embodiment, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 19, in the present embodiment,
As outputs of the selector 26, four synchronization memories 27a,
27b, 27c, 27d and four simultaneous memories 27
a, 27b, 27c, and 27d, an image processing circuit 30 that performs image processing on the outputs, and a D / A that converts the four data processed by the image processing circuit 30 into analog data.
Circuits 31a, 31b, 31c, 31d and D / A circuit 3
And a band selection circuit 101 for performing a matrix operation on the outputs of 1a, 31b, 31c, and 31d and outputting three band data.

The reason why four simultaneous memories are provided is as follows.
The second filter set of the rotary filter 14 having a double structure is shown in FIG.
As shown by 0, the filter is composed of filters of four bands R2, G2, B2a and B2b, and the spectral transmission characteristics of these filters of R2, G2, B2a and B2b are as shown in FIG.

Then, the control signal from the mode switching instruction switch 41 is applied to the rotary filter 14 by the control signal of the mode switching circuit 42 so that the second filter set (R2, G2, B2a, B2
When designated in 2b), the four band images are input to the synchronization memories 27a, 27b, 27c and 27d. The four band images are subjected to processing such as color adjustment in the image processing circuit 30, and then are subjected to D / A circuits 31a, 31b, 31c, and 3
After D / A conversion in 1d, the signal is input to the band selection circuit 101.

The user designates which of the four bands to output an image on the observation monitor 5 by using the band switching instruction switch 102 provided on the operation unit of the electronic endoscope 3.

As shown in FIG. 22, the band selection circuit 101 comprises a 4 × 3 matrix circuit 105 and a matrix coefficient change circuit 106. The band switching instruction signal output from the band switching instruction switch 102 It is input to a matrix coefficient changing circuit 106 provided in the circuit 101. Matrix coefficient changing circuit 10
6 applies a predetermined matrix coefficient to the 4 × 3 matrix circuit 105 based on the band switching instruction signal.

Equation (9) shows the equation of the matrix circuit.

[0076]

(Equation 9) As shown in Expression (9), the band selection circuit 101
Input values of the band image _{(D R2, D G2, D} B2a, D B2b) by the action of matrix coefficients of 4 × 3 with respect to the three output signals _{(d r, d g, d} b) to obtain, this The signal is output to the observation monitor 5 as a three-color signal.

Equation (10) shows an example of the matrix coefficient.

[0078]

(Equation 10) The coefficient set in M1 forms an image by R2, G2, and B2a, and M2 is a setting in which B2b is used instead of B2a.
Switching between M1 and M2 is performed, for example, by setting B2a to a center wavelength for near-ultraviolet light and setting B2b to a hemoglobin absorption wavelength band (for example, 415 nm). When M2 is applied, a mode for observing minute irregularities in detail is used as a mode for observing a fine capillary network in the vicinity of the mucosal surface in detail.

Further, since the coefficient M3 constitutes an image with two bands of B2a and B2b, by forming a narrow band filter approaching around 380 nm as B2a and B2b, the change in the cell structure near the mucosal surface can be caused. It is suitable for catching a change in scattering characteristics.

If a single-color image of a certain band is simply observed as a monochrome image, it may be set as M4, or a plurality of bands may be mixed at a fixed ratio and output using the characteristics of each band. For this purpose, a coefficient can be set as in M5.

As described above, according to the present embodiment, in addition to the effects of the first embodiment, the screen becomes extremely dark when the filter is changed to switch from normal observation to narrow-band filter observation. Therefore, it is possible to obtain an illumination light amount having a brightness that can be sufficiently observed. Further, since it is possible to select which band of the plurality of filters to observe the image, the user can obtain an optimal observation image according to the use situation.

In this embodiment, the rotation filter is set to 1
4 has a double structure, but B is required to obtain the effect on the image.
When it is sufficient to change only the filters, the rotary filter may be formed in a single configuration, and the rotary filter 14 is configured by four filters as shown in FIG. For example, as shown in FIG. 24, the filter characteristic has a configuration in which only the B filter is narrowed. The purpose of this is to improve the contrast of a biological structure such as a blood vessel near the surface by narrowing the filter band by utilizing the fact that light in the vicinity of this wavelength band has a small depth of penetration into the living body. . By adopting such a configuration of the rotary filter 14, the user can obtain an optimal observation image only by instructing the band switching according to the observation situation without performing the filter switching.

[0083]

As described above, according to the present invention, it is possible to separate and visually recognize tissue information at a desired deep portion near the tissue surface of a living tissue.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a rotary filter of FIG. 1;

FIG. 3 is a diagram illustrating spectral characteristics of a first filter set of the rotary filter of FIG. 2;

FIG. 4 is a diagram illustrating spectral characteristics of a second filter set of the rotary filter of FIG. 2;

FIG. 5 is a diagram showing a layered structure of a living tissue observed by the endoscope apparatus of FIG. 1;

FIG. 6 is a view for explaining how illumination light from the endoscope apparatus shown in FIG. 1 arrives in a layer direction of a living tissue;

FIG. 7 is a view showing each band image by plane-sequential light transmitted through the first filter set of FIG. 3;

FIG. 8 is a view showing each band image by plane-sequential light transmitted through the second filter set of FIG. 4;

FIG. 9 is a view for explaining dimming control by the dimming circuit of FIG. 1;

FIG. 10 is a configuration diagram showing the configuration of the image processing circuit of FIG. 1;

11 is a diagram showing a color image of a narrow band RGB image obtained by the image processing circuit of FIG. 10;

FIG. 12 is a view for explaining creation of a matrix that maintains the average color tone in the 3 × 3 matrix circuit of FIG. 10;

FIG. 13 is a diagram showing an example of the setting of the LUT in FIG. 10;

FIG. 14 is a configuration diagram showing a configuration of a modification of the color conversion processing circuit of FIG. 10;

FIG. 15 is a configuration diagram showing a configuration of an endoscope apparatus according to a second embodiment of the present invention.

FIG. 16 is a configuration diagram showing a configuration of the image processing circuit of FIG. 15;

17 is a configuration diagram showing a configuration of a color adjustment circuit in FIG.

18 is a diagram showing the concept of hue and saturation in an L * a * b * color space in the color adjustment circuit of FIG.

FIG. 19 is a configuration diagram showing a configuration of an endoscope apparatus according to a third embodiment of the present invention.

FIG. 20 is a configuration diagram showing the configuration of the rotary filter of FIG. 19;

FIG. 21 is a diagram showing spectral transmission characteristics of G2, B2a, and B2b filters of the rotary filter of FIG. 20;

FIG. 22 is a configuration diagram showing the configuration of the band selection circuit of FIG. 19;

FIG. 23 is a configuration diagram showing a configuration of a modification of the rotation filter of FIG. 19;

24 is a diagram showing the spectral transmission characteristics of the rotation filter of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Endoscope apparatus 2 ... CCD 3 ... Electronic endoscope 4 ... Light source apparatus 5 ... Observation monitor 6 ... Image filing apparatus 7 ... Video processor 10 ... Power supply unit 11 ... Xenon lamp 12 ... Heat ray cut filter 13 ... Aperture apparatus 14 ... Rotary filter 15 ... Light guide 16 ... Condenser lens 17 ... Control circuit 18 ... Rotary filter motor 19 ... Mode switching motor 19 20 ... CCD drive circuit 21 ... Objective optical system 22 ... Amplifier 23 ... Process circuit 24 ... A / D conversion Device 25 White balance circuit 26 Selector 27, 28, 29 Simultaneous memory 30 Image processing circuit 30a Color conversion processing circuit 31, 32, 33 D / A circuit 34 Coding circuit 35 Timing generator 41 Mode switch 42: Mode switching circuit 43: Dimming circuit 44: Dimming control parameter off Circuit 61 ... 3 × 3 matrix circuit 62a, 62b, 62c, 63a, 63b, 63cLU
T… 64… Coefficient changing circuit

Continuation of the front page F term (reference) 4C061 CC06 GG01 HH51 LL01 MM03 NN01 QQ09 RR02 RR04 RR14 RR18 SS09 TT13 WW02 5C054 CA04 CB00 CC07 EB05 ED02 ED13 EE06 EJ04 FB03 FB05 HA12 5C02 GG01 BB03 GG03

Claims (2)

[Claims] 1. An endoscope having an illumination light supply unit for supplying illumination light including a visible light region, an imaging unit for irradiating the illumination light to a subject and imaging the subject by return light, and An endoscope apparatus comprising: a signal processing unit that performs signal processing on an imaging signal of the object; A band limiting unit configured to detachably arrange a band limiting unit that forms an image on the image capturing unit on an optical path from the illumination light supply unit to the image capturing unit; An endoscope apparatus, wherein color processing of the imaging signal is changed according to an arrangement state of the band limiting unit. 2. The apparatus according to claim 1, wherein the illumination light supply unit includes a light amount control unit that controls a light amount of the illumination light for each of the wavelength ranges according to a restriction of the band limitation unit. The endoscope apparatus according to claim 1.