1. Field of the Invention
The present invention relates to an endoscope apparatus and particularly relates to an endoscope apparatus which picks up an image of a living tissue and performs signal processing, and a signal processing method of the apparatus.
2. Description of the Related Art
Conventionally, endoscope apparatuses have been widely used which apply illumination light to obtain endoscope images in body cavities. In such an endoscope apparatus, an electronic endoscope is used which has image pickup means for guiding illumination light into a body cavity from a light source device with a light guide and the like and picking up an image of a subject through return light. By performing signal processing on an image pickup signal from the image pickup means by a video processor, an endoscope image is displayed on an observation monitor to enable observation of an observation part such as a diseased part.
When a normal observation of a living tissue is performed in the endoscope apparatus, white light of a visible light region is emitted by the light source device. Frame sequential light is applied to a subject through, for example, an RGB rotary filter and the like, and return light obtained from the frame sequential light is synchronized and is subjected to image processing by the video processor, so that a color image is obtained. Alternatively, a color chip is placed at a front of an image pickup surface of the image pickup means in the endoscope, and the return light obtained from white light is separated into color components to pick up an image and the image is subjected to image processing by the video processor, so that a color image is obtained.
On a living tissue, light absorption characteristics and scattering characteristics vary with the wavelength of applied light. For example, Japanese Patent Application Laid-Open Publication No. 2002-95635 proposes a narrow-band light endoscope apparatus which emits illumination light of a visible light region, irradiates a living tissue with narrow-band RGB frame sequential light having discrete spectral characteristics, and obtains tissue information at a desired depth of the living tissue.
An endoscope apparatus according to an aspect of the present invention includes:
an illuminating unit for applying illumination light to a subject;
a biological image information acquiring unit for receiving a subject image of the subject having been irradiated with the illumination light from the illuminating unit, and obtaining biological image information of the subject;
a band limiting unit which is disposed on an optical path from the illuminating unit to the biological image information acquiring unit and limits, to a predetermined bandwidth, at least one of a plurality of wavelength bands allocated according to penetration depths of light in the subject;
a biological image information converting section for converting the biological image information obtained by the biological image information acquiring unit, to first biological image signal information corresponding to irradiation with band limited light of the plurality of wavelength bands with the predetermined bandwidth and second biological image information corresponding to irradiation with the illumination light; and
a display image generating unit for generating a display image to be displayed on a display unit, based on the first biological image signal information and the second biological image signal information which have been converted by the biological image information converting section.
A signal processing method of an endoscope apparatus according to an aspect of the present invention includes:
an illuminating step of applying illumination light to a subject;
a biological image information acquiring step of receiving a subject image of the subject having been irradiated with the illumination light, and obtaining biological image information of the subject;
a band limiting step of limiting, to a predetermined bandwidth, at least one of a plurality of wavelength bands allocated according to penetration depths of light in the subject, on an optical path from the illuminating unit to the biological image information acquiring unit;
a biological image information converting step of converting the biological image information obtained in the biological image information acquiring step, to first biological image signal information corresponding to irradiation with band limited light of the plurality of wavelength bands with the predetermined bandwidth and second biological image information corresponding to irradiation with the illumination light; and
a display image generating step of generating a display image to be displayed on a display unit, based on the first biological image signal information and the second biological image signal information which have been converted in the biological image information converting step.
Embodiments of the present invention will be described below in accordance with accompanying drawings.
As shown in
The light source device 4 includes a xenon lamp 11 acting as illuminating means for emitting illumination light (white light), a heat ray cut-off filter 12 for cutting off heat rays of white light, a beam limiting device 13 for controlling an amount of white light having passed through the heat ray cut-off filter 12, a rotary filter 14 acting as band limiting means for limiting illumination light to frame sequential light, a condenser lens 16 for condensing frame sequential light, which has passed through the rotary filter 14, on an incidence plane of a light guide 15 disposed in the electronic endoscope 3, and a control circuit 17 for controlling a rotation of the rotary filter 14.
As shown in
As shown in
The xenon lamp 11, the beam limiting device 13, and the rotary filter motor 18 are fed with power from a power supply section 10.
The video processor 7 includes a CCD drive circuit 20, an amplifier 22, a process circuit 23, an A/D converter 24, a white balance circuit (W.B) 25, a selector 100, a respective band signal conversion section 101 acting as biological image information converting means, a selector 102, a γ correction circuit 26, an expansion circuit 27, an emphasis circuit 28, a selector 29, synchronization memories 30, 31, and 32, an image processing circuit 33, D/A circuits 34, 35, and 36, a timing generator (T.G) 37, a control circuit 200, and a synthesis circuit 201 acting as display image generating means.
The CCD drive circuit 20 drives the CCD 2 provided in the electronic endoscope 3 and outputs a frame sequential image pickup signal synchronized with a rotation of the rotary filter 14. The amplifier 22 amplifies the frame sequential image pickup signal which has been obtained by picking up an image in a body cavity with the CCD 2 through an objective optical system 21 provided on an end of the electronic endoscope 3.
The process circuit 23 performs correlated dual sampling, noise removal, and the like on the frame sequential image pickup signal having passed through the amplifier 22. The A/D converter 24 converts the frame sequential image pickup signal, which has passed through the process circuit 23, to a digital frame sequential image signal.
The W.B 25 performs gain control and white balance processing on the frame sequential image signal, which has been digitized by the A/D converter 24, such that an R signal of the image signal and a B signal of the image signal have an equal brightness relative to a G signal of the image signal, for example (in other words, the W.B 25 obtains the R, G, and B signals when a subject has a white surface, for example, in a state in which a white cap is attached to the end of the electronic endoscope 3, and the W.B 25 multiplies the R signal and the B signal by a gain coefficient calculated based on a ratio of brightness relative to the G signal, so that white balance processing is performed so as to generate the R and B signals with a brightness equal to the brightness of the G signal).
The selector 100 outputs the frame sequential image signal from the W.B 25 dividedly to parts of the respective band signal conversion section 101. The respective band signal conversion section 101 converts the image signal from the selector 100, to a normal light observation image signal and a narrow-band light observation image signal. The selector 102 sequentially outputs the frame sequential image signals of the normal light observation image signal and the narrow-band light observation image signal from the respective band signal conversion section 101, to the γ correction circuit 26 and the synthesis circuit 201.
The γ correction circuit 26 performs γ correction on the frame sequential image signal from the selector 102 or the synthesis circuit 201. The expansion circuit 27 expands the frame sequential image signal having been subjected to γ correction by the γ correction circuit 26. The emphasis circuit 28 performs edge enhancement on the frame sequential image signal having been expanded by the expansion circuit 27. The selector 29 and the synchronization memories 30, 31, and 32 are provided to synchronize the frame sequential image signal from the emphasis circuit 28.
The image processing circuit 33 reads the frame sequential image signals stored in the synchronization memories 30, 31, and 32, and corrects a moving image color drift and so on. The D/A circuits 34, 35, and 36 convert the image signal from the image processing circuit 33 to analog video signals and output the signals to the observation monitor 5. The T.G 37 is fed with a sync signal, which has been synchronized with a rotation of the rotary filter 14, from the control circuit 17 of the light source device 4 and outputs various timing signals to the circuits in the video processor 7.
The electronic endoscope 2 further includes a mode switching switch 41 for feeding an output to a mode switching circuit 42 in the video processor 7. The mode switching circuit 42 of the video processor 7 outputs a control signal to a dimming control parameter switching circuit 44 and the control circuit 200. A dimming circuit 43 controls the beam limiting device 13 of the light source device 4 based on the dimming control parameter from the dimming control parameter switching circuit 44 and the image pickup signal having passed through the process circuit 23, so that a brightness is properly controlled.
Referring to
As shown in
Further, in the respective band signal conversion section 101, the G signal which is the color signal from the selector 100 is a wide-band G image signal suitable for a normal observation. The G signal is passed through the respective band signal conversion section 101 and is outputted to the selector 102 as a normal light observation G signal (hereinafter, will be referred to as WLI-G), and the G signal is outputted to the synchronization memory 110 through a band-pass filter (BPF) 111. Since the G signal is passed through the BPF 111 having the amplitude characteristics of
Moreover, in the respective band signal conversion section 101, the B signal which is the color signal from the selector 100 is outputted to the synchronization memory 110, is subjected to a predetermined brightness adjustment performed in a brightness adjustment circuit 113 through a low-pass filter (LPF) 112, and is outputted to the selector 102 as a normal light observation B signal (hereinafter, will be referred to as WLI-B). The B signal which is the color signal from the selector 100 is a narrow-band B image signal suitable for a narrow-band light observation. Since the B signal is passed through the LPF 112, a low-contrast image is generated which is equivalent to an image obtained by irradiation with illumination light having spectral characteristics with a wider band than illumination light having passed through the B filter portion 14b. Further, the B image signal is an image signal obtained by irradiation with narrow-band light on a blue short-wavelength side. Light is considerably absorbed by blood and so on and thus darkness increases. Therefore, the brightness adjustment circuit 113 is provided in the post-stage of the LPF 112 to adjust a brightness to a desired brightness and output the B signal as WLI-B to the selector 102.
The color signals inputted to the synchronization memory 101 are subjected to predetermined color conversion by a color conversion circuit 114 as expressed in formula (1) and are outputted to the selector 102 through a frame sequential circuit 115 as a frame sequential narrow-band light observation R signal (hereinafter, will be referred to as NBI-R), a frame sequential narrow-band light observation G signal (hereinafter, will be referred to as NBI-G) and a frame sequential narrow-band light observation B signal (hereinafter, will be referred to as NBI-B).
where m1, m2, and m3 represent color conversion coefficients (real numbers) and r, g, and b represent color signals of R, G, and B which are inputted to the color conversion circuit 114.
The selector 102 outputs the frame sequential color signals of WLI-R, WLI-G, and WLI-B which compose the normal light observation image and the frame sequential color signals of NBI-R, NBI-G, and NBI-B which compose the narrow-band light image to the γ correction circuit 26 or the synthesis circuit 201 based on the control signal from the control circuit 200.
The image processing circuit 33 makes a moving image color drift correction to the color signals inputted from the synchronization memories 30, 31, and 32 and generates image signals to be outputted to the D/A circuits 34, 35, and 36. In other words, when the frame sequential color signals of WLI-R, WLI-G, and WLI-B are inputted, the image processing circuit 33 generates the normal light observation image. When the frame sequential color signals of NBI-R, NBI-G, and NBI-B are inputted, the image processing circuit 33 generates the narrow-band light image. When the image processing circuit 33 is fed with frame sequential color signals of a synthetic image signal which will be described later, the image processing circuit 33 generates a synthetic image signal having been subjected to a moving image color drift correction.
Further, as shown in
In other words, in the present embodiment, the selector 102 is switched based on the control signal from the control circuit 200 to input two image signals of the same color signal (in the case of the R signal, WLI-R and NBI-R) to the synthesis circuit from memories (not shown) included in the selector 102, in a display mode for simultaneously displaying the normal light observation image and the narrow-band light observation image on the observation monitor 5.
The synthesis circuit 201 reduces the two inputted image signals and then synthesizes the image signals, so that a synthetic image signal is generated. The synthesis circuit 201 outputs the generated signal to the γ correction circuit 26 (the G and B signals are similarly synthesized, and WLI-R and NBI-R, WLI-G and NBI-G, and WLI-B and NBI-B are controlled based on the control signal from the control circuit 200, which will be described later, such that the signals are sequentially inputted to the synthesis circuit 201, the synthetic image signal being outputted from the synthesis circuit 201 to the γ correction circuit 26 in a frame sequential manner).
In a mode for displaying only one of the normal light observation image and the narrow-band light observation image, the selector 102 is not switched to output the image signals to the synthesis circuit 201 based on the control signal from the control circuit 200 but is switched to output the R signal, the G signal, and B signal of the normal light observation image or the narrow-band light observation image to the γ correction circuit 26 in a frame sequential manner.
The control circuit 200 identifies the mode based on a mode switching signal from the mode switching circuit 42 and switches the selector 102. After that, the control circuit 200 controls the R, G, and B signals in the selector 102 based on the timing signal from the T.G 37 such that the signals are sequentially outputted to the synthesis circuit 201 or the γ correction circuit 26 (when the signals are outputted to the synthesis circuit 201, WLI-R and NBI-R are simultaneously outputted, WLI-G and NBI-G are outputted at a next time, and then WLI-B and NBI-B are outputted at a subsequent time, which is repeatedly performed, and when the signals are outputted to the γ correction circuit 26, for example, in a mode for displaying the normal light observation image, WLI-R→WLI-G→WLI-B is repeated.).
The selector 102 includes the memories (not shown) in which WLI-R, WLI-G, WLI-B, NBI-R, NBI-G, and NBI-B inputted from the respective band signal converter 101 are stored based on the control signal from the control circuit 200 only in the mode for simultaneously displaying the normal light observation image and the narrow-band light image.
In the above explanation, the synthesis circuit 201 reduces and synthesizes the two image signals so as to laterally place the image signals. The synthesis circuit 201 may synthesize the image signals by detecting only subject image signals in the image signals (image signal portions based on a subject image, the image signals corresponding to the normal light observation image other than a margin in
In the present embodiment, as shown in
In other words, in the case of the mode for displaying only one of the normal light observation image and the narrow-band light observation image, the γ correction circuit 26 is fed with the control signal (the display mode for displaying only one of the normal light observation image and the narrow-band light observation image has been identified) from the control circuit 200.
As shown in
On the other hand, in the mode for simultaneously displaying the normal light observation image and the narrow-band light observation image, the γ correction circuit 26 is fed with a sync signal outputted from the synthesis circuit 201 and is fed with the control signal (the simultaneous display mode has been identified) from the control circuit 200.
The γ correction circuit 26 identifies, as shown in
As described above, in the present embodiment, the respective band signal conversion section 101 generates WLI-R, WLI-G, and WLI-B for generating the normal light observation image and NBI-R, NBI-G, and NBI-B for generating the narrow-band light image, based on the RGB signals obtained by irradiation with frame sequential light of a set of the rotary filter 14. In other words, by irradiation with frame sequential light through the rotary filter 14 made up of the set of the R filter portion 14r, the G filter portion 14g, and the B filter portion 14b, the normal light observation image and the narrow-band light image can be generated in real time. Thus it is possible to simplify the configuration of the apparatus and simultaneously observe the normal light observation image and the narrow-band light image.
The synthesis circuit 201 synthesizes the normal light observation image and the narrow-band light image, so that the normal light observation image and the narrow-band light image can be simultaneously observed.
The second embodiment is substantially the same as the first embodiment and thus only different points will be described below. The same configurations as in the first embodiment will be indicated by the same reference numerals and the explanation thereof is omitted.
In the first embodiment, the normal light observation image and the narrow-band light image are generated by frame sequential image pickup observation through the rotary filter 14. In the present embodiment, as shown in
In a video processor 7 of the present embodiment, as shown in
The respective signal conversion section 101 is configured substantially as in the first embodiment. As shown in
The color conversion circuit 114 performs predetermined color conversion on the inputted image signals and outputs the signals to the selector 102 as NBI-R, NBI-G, and NBI-B.
After that, the selector 102 outputs WLI-R, WLI-G, WLI-B, and NBI-R, NBI-G, and NBI-B to a γ correction circuit 26 or a synthesis circuit 201 based on a control signal from a control circuit 200. The synthesis circuit 201 synthesizes the inputted image signals.
In other words, in the present embodiment, the selector 102 is switched to input the six image signals (WLI-R, WLI-G, WLI-B, NBI-R, NBI-G, and NBI-B) to the synthesis circuit 201 from memories (not shown) included in the selector 102, in a display mode for simultaneously displaying the normal light observation image and the narrow-band light observation image on an observation monitor 5.
The synthesis circuit 201 reduces the two image signals of the same color (WLI-R and NBI-R, WLI-G and NBI-G, and WLI-B and NBI-B) and then synthesizes the image signals, so that a synthetic image signal (RGB image signal) is generated. The synthetic image signal is outputted to the γ correction circuit 26.
In a mode for displaying only one of the normal light observation image and the narrow-band light observation image, the selector 102 is not switched to output the image signals to the synthesis circuit 201 based on the control signal from the control circuit 200 but is switched to output the R signal, the G signal, and B signal of the normal light observation image or the narrow-band light observation image to the γ correction circuit 26.
The control circuit 200 identifies the mode based on a mode switching signal from a mode switching circuit 42 and switches the selector 102. After that, the control circuit 200 controls the R, G, and B signals in the selector 102 based on a timing signal from a T.G 37 such that the signals are outputted to the synthesis circuit 201 or the γ correction circuit 26 (when the signals are outputted to the synthesis circuit 201, WLI-R, WLI-G, WLI-B, NBI-R, NBI-G, and NBI-B are simultaneously outputted, and when the signals are outputted to the γ correction circuit 26, for example, in a mode for displaying the normal light observation image, WLI-R, WLI-G, and WLI-B are controlled to be simultaneously outputted from the selector 102).
In the above explanation, the synthesis circuit 201 reduces and synthesizes the two image signals of the same color signal so as to laterally place the image signals. The synthesis circuit 201 may synthesize the image signals by detecting only subject image signals in the image signals (image signal portions based on a subject image, the image signals corresponding to the normal light observation image other than a margin in
The γ correction circuit 26 identifies, as in the first embodiment, the WLI image signal and the NBI image signal based on the control signal and uses gamma-1 characteristics for the WLI image signal and gamma-2 characteristics for the NBI image signal. For the identification of the image signals, image region information is used. For example, in display of
In the case of the mode for displaying only one of the normal light observation image and the narrow-band light observation image, the γ correction circuit 26 makes a γ correction to the normal light observation image according to the gamma-1 characteristics based on the control signal from the control signal, and makes a γ correction to the narrow-band light observation image according to the gamma-2 characteristics (in this case, the γ correction circuit 26 does not identify the image signal based on the control signal).
The video processor 7 of the present embodiment includes, as in the first embodiment, the γ correction circuit 26 for making a γ correction to the image signals having passed through the selector 102, an expansion circuit 27 for expanding the image signals having been subjected to the γ correction, and an emphasis circuit 28 for performing edge enhancement on the expanded image signals. The image signals from the emphasis circuit 28 are converted to analog video signals by D/A circuits 34, 35, and 36 and are outputted to the observation monitor 5.
In the present embodiment, as shown in
Thus the present embodiment can achieve the same effect as in the first embodiment.
The third embodiment is substantially the same as the second embodiment and thus only different points will be described below. The same configurations as in the second embodiment will be indicated by the same reference numerals and the explanation thereof is omitted.
In the present embodiment, as shown in
In a video processor 7 of the present embodiment, as shown in
The transmission property of the heat ray cut-off filter 12 serving as band limiting means is narrow-band characteristics as shown in
Thus the present embodiment can achieve the same effect as in the second embodiment.
The transmission property of the heat ray cut-off filter 12 is not limited to the property of
The present invention is not limited to the foregoing embodiments and various changes and modifications can be made without changing the subject matter of the present invention.
Number | Date | Country | Kind |
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2006-223576 | Aug 2006 | JP | national |
This application is a continuation application of PCT/JP2007/058671 filed on Apr. 20, 2007 and claims benefit of Japanese Application No. 2006-223576 filed in Japan on Aug. 18, 2006, the contents of which are incorporated herein by this reference.
Number | Date | Country | |
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Parent | PCT/JP2007/058671 | Apr 2007 | US |
Child | 12372202 | US |