JP3179166B2 - Electronic endoscope device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus having means for decomposing an image into a plurality of color signals and generating a luminance signal from the decomposed color signals.

[0002]

2. Description of the Related Art In recent years, by inserting an elongated insertion portion into a body cavity, it is possible to observe internal organs in the body cavity or to perform various treatments using a treatment tool inserted into a treatment tool channel as necessary. Endoscopes are widely used. Also, various electronic endoscopes using a solid-state imaging device such as a charge-coupled device (CCD) as an imaging unit have been proposed.

[0003] In an endoscope apparatus provided with such an electronic endoscope, brightness is important. In particular, it is determined whether a distant point can be seen brightly and whether a bleeding source can be seen brightly during a major bleeding. Absolute light brightness is important.

[0004] On the other hand, conventionally, there has been proposed an AGC (auto gain controller) or the like which increases the gain of an image signal from a solid-state image sensor, or a device which increases the number of light guides to increase the amount of illumination. Have been. Furthermore, RG is used to improve the resolution.
With respect to the B component, there have been proposed ones in which the γ characteristic is changed more than usual and the I component (brightness) is subjected to unsharp masking.

[0005]

SUMMARY OF THE INVENTION However, AGC
(Auto gain controller) and the like which increase the gain of the image signal from the solid-state image sensor have a drawback that the S / N ratio is deteriorated at the time of increasing the gain, and the number of light guides is increased to increase the amount of illumination light. However, there is a problem that the insertion portion of the endoscope is made thicker. Further, any of the RGB components that change the γ characteristic more than usual and perform the unsharp masking process on the I component (brightness) requires a complicated and large-scale processing circuit.

On the other hand, the body cavity wall to be observed by the endoscope
The spectral reflectance of the R component is overwhelmingly higher than the G and R components, and the high frequency component of the spatial frequency in the image is:
There are many G component images and B component images, but few R component images.

The present invention has been made in view of the above circumstances, and realizes improvement in brightness and resolution with a simple circuit configuration by performing signal processing corresponding to the characteristics of an endoscope image. It is an object of the present invention to provide an electronic endoscope apparatus capable of performing the above.

[0008]

Means and actions for solving the problems The above object has been achieved.
An electronic endoscope apparatus according to the present invention includes: an imaging unit configured to image a subject; and an imaging signal output from the imaging unit.
A color signal generating means for generating a higher plurality of color signals, the double
Number of chrominance signals are mixed at a specified first ratio to form a first luminance signal.
First luminance signal generating means for generating a plurality of colors;
A color difference signal is generated based on the signal and the first luminance signal.
Color difference signal generating means, and converting the plurality of color signals to the first
Mixing at a second ratio different from the ratio, and forming the second luminance signal
Second luminance signal generating means for generating the second luminance signal;
Signal and a color signal for generating a video signal based on the color difference signal.
Signal generation means .

[0009]

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

FIGS. 1 to 3 relate to an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of an endoscope apparatus. FIG. 2 is an explanatory view for explaining characteristics of a video signal of an observation image. FIG. 2 is a side view showing the entire endoscope apparatus.

An endoscope apparatus according to one embodiment includes an electronic endoscope 1 as shown in FIG. This electronic endoscope 1
Has, for example, an elongated, flexible insertion portion 2, and a large-diameter operation portion 3 is connected to the rear end of the insertion portion 2. A flexible universal cord 4 extends laterally from the rear end of the operation unit 3, and a connector 5 is provided at the tip of the universal cord 4. The electronic endoscope 1 is connected via the connector 5 to a video processor 6 having a light source device and a signal processing circuit built therein. Further, a color monitor 7 is connected to the video processor 6.

On the distal end side of the insertion portion 2, a rigid distal end portion 9 and a bending portion 10 which can be bent rearward adjacent to the distal end portion 9 are sequentially provided. By rotating a bending operation knob 11 provided on the operation section 3, the bending section 10 can be bent in the left-right direction or the up-down direction. Further, the operation section 3 is provided with an insertion port 12 which communicates with a treatment instrument channel provided in the insertion section 2.

As shown in FIG. 1, a light guide 13 for transmitting illumination light is inserted into the insertion section 2 of the electronic endoscope 1. The distal end surface of the light guide 13 is disposed at the rear of an illumination lens 14 provided at the distal end 9 of the insertion section 2 so that illumination light can be emitted from the illumination lens 14. The light guide 13 has an incident end side inserted into the universal cord 4 and connected to the connector 5. The distal end 9 is provided with an objective lens system 15.
The solid-state imaging device 16 is disposed at the imaging position of No. 5.
The solid-state imaging device 16 has sensitivity in a wide wavelength range from the ultraviolet region to the infrared region including the visible region, and signal lines 17 and 18 are connected to the solid-state imaging device 16.

On the other hand, the video processor 6 is provided with a lamp 19 that emits light in a wide band from ultraviolet light to infrared light. As the lamp 19, a general xenon lamp, a strobe lamp, or the like can be used.
The xenon lamp and the strobe lamp emit a large amount of ultraviolet light and infrared light as well as visible light. This lamp 1
Reference numeral 9 denotes a power supply from a power supply 20. A rotary filter 22 driven by a motor 21 is provided in front of the lamp 19. In the rotary filter 22, filters for transmitting light in respective wavelength regions of red (R), green (G), and blue (B) for normal observation are arranged along the circumferential direction.

The rotation of the motor 21 is controlled by a motor driver 23 to be driven.

R, G, R, G,
The light separated in a time series into the light of each wavelength region of B is condensed by the condenser lens 24 and is incident on the incident end of the light guide 13, and is guided to the illumination lens 14 via the light guide 13. Then, the light is emitted from the illumination lens 14 to illuminate the observation site.

The return light from the observation site due to the illumination light is imaged on the solid-state image pickup device 16 by the objective lens system 15 and photoelectrically converted. A drive pulse from a drive circuit 25 in the video processor 6 is applied to the solid-state imaging device 16 via the signal line 17, and readout and transfer are performed by the drive pulse. The video signal read from the solid-state imaging device 16 is input to the preamplifier 26.

The video signal amplified by the preamplifier 26 is supplied to the video processor 6 via the signal line 18.
Is input to the sample and hold circuit 27 provided in the
The digital signal is converted by the A / D converter 28. The digital video signal is converted by a multiplexer 29 into, for example, a frame memory 30 corresponding to each of red (R), green (G), and blue (B) colors.
r, 30g, and 30b. The frame memories 30r, 30g, 30b are:
The D / A converters 31r, 31g,
31b converts the signal into an analog signal.

D / A converters 31r, 31g, 31b
Analog component signals [R], [G], [B]
Are input to a normal luminance calculation circuit 32N that generates a normal luminance signal [Y] by calculation.

Here, [Y] is the normal luminance calculation circuit 32
By N, [Y] = 0.3 [R] +0.59 [G] +0.11 [B].

The D / A converters 31r, 31g,
31b, analog component signals [R], [G],
[B] becomes relatively high-frequency analog signals [RH], [GH], and [BH] via high-frequency bandpass filters (hereinafter, referred to as HPFs) 33r, 33g, and 33b.
H], [GH], and [BH] are input to a high-frequency luminance calculation circuit 32H that generates a high-frequency luminance signal [YH] by calculation.

Here, [YH] is, for example, [YH] = 0.1 [RH] +0.6 [GH] +0.3 [BH] by the high-frequency luminance calculation circuit 32H.

The HPFs 33r, 33g, and 33b may have the same characteristics or may be individually set, or may be a type of endoscope such as a stomach endoscope and a colon endoscope. May be changed in accordance with the characteristics of the subject to be imaged.

[YH] is [YH] = 0.1 [RH] +0.6 [GH] +0.3 [BH], but is not limited to this. For example, [YH] = 0.5 [GH] +0.5 [BH], and the calculation formula used for the calculation of [YH] may be varied according to the characteristics of the subject.

D / A converters 31r, 31g, 31b
Analog component signals [R], [G], [B]
Are also converted into relatively low-frequency analog signals [RL], [GL], [BL] via low-frequency band-pass filters (hereinafter, referred to as LPFs) 34r, 34g, 34b, and [R
[L], [GL], and [BL] are input to a low-frequency luminance calculation circuit 32L that generates a low-frequency luminance signal [YL] by calculation.

Here, [YL] is, for example, [YL] = 0.6 [RL] +0.3 [GL] +0.1 [BL] by the low-frequency luminance calculation circuit 32L.

The LPFs 34r, 34g and 34b may have the same characteristics or may be individually set, and may be of a type of endoscope such as a stomach endoscope and a large intestine endoscope. May be changed in accordance with the characteristics of the subject to be imaged.

[YL] is set to [YL] = 0.6 [RL] +0.3 [GL] +0.1 [BL], but is not limited thereto. For example, [YL] = 0.7 [RL] +0.3 [GL], and the calculation formula used for the calculation of [YL] may be varied according to the characteristics of the subject.

Further, the LPF 34r and the HPF 33r are
The analog component signal [R] from the D / A converter 31r may be simply divided into two, and the LPF 34r
May be provided between the pass band of the HPF 33r and the pass band of the HPF 33r. LPF34g, HPF33g, LPF34
The same applies to b and the HPF 33b.

The normal luminance signal [Y] output from the normal luminance calculation circuit 32N is input to an R subtraction circuit 35r and a B subtraction circuit 35b.
The color difference signal [RY] is generated by subtracting the normal luminance signal [Y] from the output [R] of the converter 31r, and the B subtraction circuit 35r outputs the color difference signal [RY] from the output [B] of the D / A converter 31b. The color difference signal [B] obtained by subtracting the normal luminance signal [Y]
−Y] is generated.

The high-frequency luminance signal [YH] output from the high-frequency luminance operation circuit 32H and the low-frequency luminance signal [YL] output from the low-frequency luminance operation circuit 32L are modulated.
The modulation circuit 36 synthesizes [YH] and [YL] to generate a synthesized luminance signal [Y '].

The chrominance signals [RY] and [BY] and the synthesized luminance signal [Y '] are output, for example, by the NTSC encoder circuit 3.
7 and converted into an NTSC composite signal.
The image is input to the color monitor 7, and the observation site is displayed in color by the color monitor 7.

In the video processor 6, a timing generator (not shown) for generating the timing of the entire system is provided, and the circuits such as the motor driver 23, the drive circuit 25, and the multiplexer 29 are synchronized.

The operation of the thus configured endoscope apparatus will be described.

By inserting the insertion section 2 of the electronic endoscope 1 into the body cavity and irradiating the illumination light from the lamp 19 to the observation site, the solid-state imaging device 16 is, for example, as shown in FIG. Captures a unique observation image. A video signal read from the solid-state imaging device 16 is amplified by a preamplifier 27,
A / D converter 2 via sample and hold circuit 27
8 to be converted into a digital signal. This digital signal is supplied to a frame memory 30r, 30r by a multiplexer 29 for each frame of each signal of R, G, B.
g, 30b. Frame memories 30r, 30
R, G, B digital signals stored in g, 30b are
The D / A converters 31r, 31g,
The signal is converted into an analog signal by 31b.

In the body cavity, there are many R components, and the component signals [R], [G], and [G] of the analog signals converted into analog signals by the D / A converters 31r, 31g and 31b.
[B] is as shown in FIG. That is, the component signal [R] has a high signal level but a small amount of high frequency components. Conversely, the component signals [G] and [B] have a low signal level but a large number of high frequency components as compared with [R]. Therefore,
As shown in FIG. 2C, the ratio of [G] and / or [B] is reduced in the low frequency region of the spatial frequency with respect to the normal luminance signal [Y], as shown in FIG. To increase
Further, in the high frequency region of the spatial frequency, when the ratio of [G] and / or [B] is reduced, the high frequency component of [R] is small and the resolution is deteriorated. A composite luminance signal [Y '] in which the ratio is increased and the ratio of [R] is decreased.

Therefore, [R], [G] and [B] are converted to LP
[RL], [GL], [BL] are extracted through F32L,
[RH], [GH], [BH] via HPF32H.
Is extracted. Next, in the low-frequency luminance calculation circuit 32L,
[YL] is generated using [RL], [GL], and [BL],
In the high-frequency luminance calculation circuit 32H, [RH], [GH],
[YH] is generated using [BH]. The modulation circuit 36
Low frequency luminance operation circuit 32L and high frequency luminance operation circuit 32H
A composite luminance signal [Y '] is obtained from [YL] and [YH] generated in step (1).

On the other hand, [Y] is calculated from [R], [G], and [B] by the normal luminance calculation circuit 32N, and the color difference signal [R−] is calculated from the [Y] and [R] by the R subtraction circuit 35r.
Y], and similarly, a color difference signal [B−Y] is generated from [Y] and [B] by the B subtraction circuit 35b.

The obtained combined luminance signal [Y ′] and color difference signals [RY] and [BY] are converted into an NTSC encoder circuit 3.
7 to convert the signal into an NTSC composite signal. The NTSC composite signal is input to the color monitor 7,
The observation site is displayed in color.

As described above, the endoscope apparatus of the present embodiment has a higher S / N than the conventional example in which the gain of the component signal [R] is simply increased, and for example, [YH] = If 0.5 [GH] +0.5 [BH] [YL] = 0.7 [RL] +0.3 [GL], the brightness of each of the RGB colors of the subject image formed on the solid-state imaging device 16 (Because the high-frequency component does not affect the brightness as a whole, the brightness of the low-frequency component for each of the RGB colors or the sum of the low-frequency components) indicates that the level of each color signal is, for example, [R]: [G] : [B] = 5A: A: A (A; proportionality constant), the normal luminance signal [Y] is [Y] = 2.2A, whereas the composite luminance signal [Y '] is [ Y '] ~
[YL] = 3.8A (The symbols "-" are "almost equal.")
Represents ), So that the brightness is 1.7 times higher and the brightness can be improved. In addition, the color difference signal [R-
Since [Y] and [BY] are generated from the normal luminance signal [Y], the brightness can be improved and the normal color reproduction can be realized as described above.

Further, in the feature that the high frequency component of the spatial frequency in the image is large for the G component image and the B component image but is small for the R component image, the high frequency component of the synthesized luminance signal [Y '] has the R component. Is smaller than the normal luminance signal [Y] or is not included at all, so that the contrast of a fine structure can be improved.

In this embodiment, the description has been made using the image pickup means of the frame sequential method. However, the present invention is not limited to this. For example, an image pickup means of a single-plate color method having a color mosaic filter may be used. Although the output to the color monitor 7 is a composite signal, the present invention is not limited to this. For example, an RGB output may be used.

[0043]

As described above, according to the present invention, the endoscope apparatus of the present invention performs signal processing corresponding to the characteristics of an endoscope image, thereby achieving a simple circuit configuration and brightness. There is an effect that improvement in resolution and resolution can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an endoscope apparatus according to one embodiment.

FIG. 2 is an explanatory diagram illustrating characteristics of a video signal of an observation image according to one embodiment.

FIG. 3 is a side view showing the entire endoscope apparatus according to one embodiment.

[Description of Signs] 1 ... Electronic endoscope 6 ... Video processor 7 ... Color monitor 30r-30b ... Frame memory 33r-33b ... HPF 34r-34b ... LPF 32N ... Normal luminance operation circuit 32H ... High frequency luminance operation circuit 32L ... Low Frequency / luminance calculation circuit 36: Modulation circuit 37: NTSC encoder circuit

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 1/00-1/32 G02B 23/24 G06T 1/00-1/40 G06T 3/00-5/50 G06T 9 / 00-9/40 H04N 7/18

Claims (1)

(57) [Claims] An image pickup means for picking up an image of a subject, and a plurality of color signals based on an image pickup signal output from the image pickup means
And a color signal generating means for generating the first color signal and a plurality of color signals at a specified first ratio.
A first luminance signal generating means for generating a luminance signal; and a color difference between the plurality of color signals and the first luminance signal.
A color difference signal generating means for generating a signal; and a second ratio different from the first ratio for the plurality of color signals.
A second luminance signal that mixes together to generate a second luminance signal
A video signal based on the generating means and the second luminance signal and the color difference signal
Electronic endoscope apparatus characterized by comprising a video signal generating means for generating a.