JP2008104770A - Image processor for electronic endoscope system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor for electronic endoscope system, which is capable of preventing the phenomenon of increase in video signal value corresponding to the properties of an electronic scope. <P>SOLUTION: This image processor for an electronic endoscope system includes a pulse generating section for outputting clamp pulses with a pulse width corresponding to the properties of a mounted electroscope and the black-level sampling period, a sag correction circuit which adjusts the black level by sampling the black level with respect to a luminance signal outputted from the electronic scope during a period corresponding to a pulse width of a clamp pulse output the pulse generating section, and a video signal processing section for subjecting the image data acquired by the electroscope to image processing based on the luminance signal outputted via the sag correction circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image processor of an electronic endoscope system, and more particularly to an image processor that accurately adjusts a black level.

  Conventionally, an electronic endoscope system including an electronic scope on which an image sensor is mounted has been proposed.

Patent Document 1 discloses an electronic endoscope system that performs sag correction and black level adjustment using a clamp circuit in an image processor that performs image processing on image data obtained by imaging with an electronic scope.
JP 2000-350194 A

  However, although a capacitor is used in the clamp circuit in Patent Document 1 or the like, if the capacity of the capacitor is not sufficient, depending on the characteristics of the attached electronic scope, the black level signal cannot be held constant, and the video signal ( A signal lifting phenomenon occurs in which the digital component signal) value increases with time, and in appearance (output image), a phenomenon occurs in which the black level floats upward.

  Accordingly, an object of the present invention is to provide an image processing processor of an electronic endoscope system that can suppress the phenomenon of a video signal value rising corresponding to the characteristics of an electronic scope.

  An image processing processor of an electronic endoscope system according to the present invention includes a pulse generation unit that outputs a clamp pulse having a pulse width corresponding to characteristics of an attached electronic scope and a period during which black level samples can be extracted. The sag correction circuit extracts black level samples from the luminance signal output from the electronic scope and adjusts the black level during the period corresponding to the pulse width of the clamp pulse output from the pulse generator. And a video signal processing unit that performs image processing on the image data acquired by the electronic scope based on the luminance signal output via the sag correction circuit.

  Preferably, the pulse generator outputs a clamp pulse in consideration of a delay period corresponding to the burst signal.

  Preferably, the pulse generation unit obtains identification information for identifying the attached electronic scope, and a pulse width corresponding to the attached electronic scope based on the identification information from the determination unit. And an adjusting unit to be set.

  As described above, according to the present invention, it is possible to provide an image processing processor of an electronic endoscope system that can suppress a phenomenon in which a video signal value rises in accordance with the characteristics of an electronic scope.

  Hereinafter, the configuration of the electronic endoscope system according to the present embodiment will be described with reference to the drawings. The electronic endoscope system 1 according to the present embodiment includes an electronic scope 10, an image processor 20, and a monitor 30.

  The electronic scope 10 includes an operation unit 11 that performs various operations while being held by a practitioner, an insertion unit 12 that is a flexible tube that has an imaging element 14 at a distal end and is inserted into a patient's body, and a signal processing circuit. And a connection unit 13 connected to an image processing processor (image processing apparatus) 20. The connection unit 13 is provided with a first ROM 15 in which identification information of the electronic scope 10 is stored.

  The connection unit 13 of the electronic scope 10 is connected to a front unit (not shown) of the image processor 20. The image processor 20 performs predetermined image processing on the image acquired by the electronic scope 10.

  A monitor 30 is connected to the image processor 20. The monitor 30 displays an image that has been image-processed by the image processor 20 and that is based on a predetermined analog video signal standard. The image processor 20 includes a printer device such as a video printer that prints out an image that has been subjected to image processing by the image processor 20 and that is based on a predetermined analog video signal standard, and an image that has been subjected to image processing by the image processor 20. An external storage device that records data or the like may be connected.

  A light guide (not shown) made of a large number of optical fibers for guiding illumination light is inserted into the electronic scope 10, and the light guide extends to the distal end of the insertion portion 12 of the electronic scope 10.

  The image processor 20 includes a pulse generator 21, a sag correction circuit 22, and a video signal processor 23. The image processor 20 acquires the electronic scope identification information from the first ROM 15 and uses it for image processing control described later.

  When the connection unit 13 of the electronic scope 10 is connected to the image processor 20, the light guide is optically connected to a light source of a light source unit (not shown). When the light source lighting operation is performed by the user, a lighting driving signal is output from the light source driving circuit of the light source unit to the light source, and white light is emitted from the light source. The amount of white light emitted from the light source is adjusted by a diaphragm mechanism (not shown) or the like, and enters the incident end of the light guide. The incident white light is guided to the tip of the insertion portion 12 of the electronic scope 10 by the light guide, and is irradiated to the object to be observed as illumination light through the light distribution optical system.

  Reflected light from the object to be observed enters the image sensor 14 through an objective optical system (not shown), and an optical image of the object to be observed is formed on the incident surface of the image sensor 14. The image sensor 14 photoelectrically converts the incident optical image of the observed object, and outputs an analog image signal based on the optical image.

  The analog image signal output from the image sensor 14 is subjected to preceding image signal processing such as A / D conversion and Y / C separation in the signal processing circuit 19 of the connection unit 13 and is input to the image processing processor 20. The synchronization signal is output to the pulse generation unit 21 through the image signal processing of the previous stage in the signal processing circuit 19, the luminance signal (Y signal) is output to the sag correction circuit 22, and other signals such as the Cb signal are the video signal processing unit. 23.

  The pulse generation unit 21 outputs a control signal for controlling each unit of the image processor 20 based on the synchronization signal output from the signal processing circuit 19 such as an FPGA (Field Programmable Gate Array). The synchronization signal includes a vertical synchronization signal and a horizontal synchronization signal. The period during which black level samples can be extracted corresponding to the vertical and horizontal sync signal rise and fall timings, and the delay period considering the burst signal (in the vertical blanking period, from the rise to the fall In the video period and the video period, a clamp pulse having a pulse width of a time width within a period during which black level samples can be extracted corresponding to the period from the rising edge to the start of video signal output) is sag corrected. It is output to the circuit 22.

  Specifically, the pulse generation unit 21 includes a scope determination circuit 25, a second ROM 27, and a timing adjustment circuit 29. The scope discriminating circuit 25 acquires the electronic scope identification information stored in the first ROM 15 of the electronic scope 10. The second ROM 27 includes identification information of the electronic scope, an optimum pulse width (according to the characteristics of the electronic scope) for each electronic scope (actually, the counter value of the time measurement counter), and a period for setting the pulse width. Store the associated data. Based on the electronic scope identification information and the data stored in the second ROM 27, the scope discriminating circuit 25 can use a fixed pulse width that is set in advance or can determine the optimum pulse width for the attached electronic scope. The adjustment circuit 29 determines whether to adjust (set an optimal pulse width) (set an optimal pulse width).

  The horizontal synchronization signal and the vertical synchronization signal from the electronic scope 10 are input to the timing adjustment circuit 29. When a fixed pulse width is available, a clamp pulse having a fixed pulse width is output from the timing adjustment circuit 29 to the sag correction circuit 22 based on the falling timing of the horizontal synchronization signal and the vertical synchronization signal. When it is necessary to adjust the optimal pulse width for the attached electronic scope, based on the horizontal synchronization signal, the falling timing of the vertical synchronization signal, and the pulse width information for each period corresponding to the identification information of the electronic scope, A clamp pulse having a pulse width that varies from period to period is output from the timing adjustment circuit 29 to the sag correction circuit 22.

  During the low output period of the clamp pulse corresponding to the pulse width, a black level sample of the digital component signal input to the sag correction circuit 22 is extracted, and black level adjustment (sag correction) is performed. In the present embodiment, the low output time of the clamp pulse is set for the characteristics of the electronic scope 10 connected to the image processor 20 and for each period within the field period.

  For example, in the pre-equalization pulse period and the post-equalization pulse period of the vertical blanking period of the field period, the period during which the black level sample of the digital component signal can be extracted is relatively long. Accordingly, the low output time of the clamp pulse is adjusted from the short time Tc1 to the long time Ta1 (see FIG. 2).

  Further, in the vertical synchronization pulse period of the vertical blanking period of the field period and the video period of the field period, the period during which the black level sample of the digital component signal can be extracted is relatively short. Thus, the low output time of the clamp pulse is adjusted within the short time Tc2 to Ta2.

  FIG. 2 shows an example of clamp pulses when three types of electronic scopes (scopes (1) to (3)) are attached to the image processor 20.

  When the scope (1) is attached, a relatively long extraction period (pulse width) Ta1 is set in the pre-equalization pulse period and the post-equalization pulse period, and the vertical synchronization pulse period and the video period are relatively long. A short extraction period (pulse width) Ta2 is set, and a relatively long extraction period (pulse width) Ta3 is set after the post-equalization pulse period until the video period starts.

  When the scope (2) is attached, a medium extraction period (pulse width) Tb1 is set in the pre-equalization pulse period and the post-equalization pulse period, and the vertical synchronization pulse period and the video period are relatively long. A short extraction period (pulse width) Tb2 is set, and a medium extraction period (pulse width) Tb3 is set between the post-equalization pulse period and the start of the video period.

  When the scope (3) is attached, a relatively short extraction period (pulse width) Tc1 is set in the pre-equalization pulse period and the post-equalization pulse period, and the vertical synchronization pulse period and the video period are relatively long. A short extraction period (pulse width) Tc2 is set, and a relatively short extraction period (pulse width) Tc3 is set after the post-equalization pulse period until the video period starts (ta1> Tb1> Tc1, Ta2). ≧ Tb2 ≧ Tc2, Ta3> Tb3> Tc3).

  The black level adjustment is performed based on the black level sample extracted during the low output period of the clamp pulse using a capacitor having a relatively small capacity in the sag correction circuit. When the low output period of the clamp pulse is set to a fixed value, the fixed value is set to a short value corresponding to the short period during which black level samples can be extracted, such as a video period. In this case, depending on the characteristics of the electronic scope 10 connected to the image processor 20, sag correction is performed, but a signal whose digital component signal value increases over time due to discharge from a capacitor having a small capacity or the like. A lifting phenomenon occurs, and in appearance (output image), a phenomenon occurs in which the black level rises to the right (a phenomenon in which the luminance on the right side of the image increases and becomes whitish).

  However, in the present embodiment, the capacitance of the capacitor in the sag correction circuit 22 is adjusted to adjust the Low output period of the clamp pulse in accordance with the characteristics of the electronic scope 10 and the length of the period during which the black level sample can be extracted. As a result, it is possible to avoid the phenomenon that the digital component signal is lifted (a phenomenon in which the black level rises to the right).

  After adjusting the black level, the luminance signal is output from the sub-correction circuit 22 to the video signal processing unit 23 and is subjected to subsequent image signal processing (amplification processing, gamma correction, contour enhancement, etc. for the digital image signal) together with other video signals. The image data is stored as image data in an image memory (not shown) provided in the signal processing unit 25. The image data in the image memory is read out in a timely manner, subjected to video signal processing conforming to the specifications of a predetermined video signal, and output to the monitor 30. As a result, the observed object image is displayed on the main monitor 30.

  Next, the flow for adjusting the length of the low output period of the clamp pulse will be described with reference to the flowchart of FIG. When the power source of the image processor 20 is turned on, a high output of clamp Hals is output from the pulse generator 21 to the sag correction circuit 22 in step S11. In step S12, it is determined whether or not the electronic scope 10 is attached to the image processor 20. If not attached, the process returns to step S11. If attached, the process proceeds to step S13.

  In step S <b> 13, a high output of the clamp hulls is performed from the pulse generator 21 to the sag correction circuit 22. In step S14, it is determined whether or not the horizontal synchronizing signal has fallen. If not, the process returns to step S13. If there is, the process proceeds to step S15.

  In step S15, delay control (control not to switch the clamp pulse to low output for a certain period of time) is performed until burst signal output is started. Thereafter, in step S16, the pulse generator 21 performs sag control. A low output of the clamp pulse is performed to the correction circuit 22. In step S17, it is determined whether or not the characteristics of the attached electronic scope 10 need to adjust the low output period of the clamp pulse. If necessary, the process proceeds to step S18, and if not necessary, the process proceeds to step S19.

  In step S18, the counter value for measuring the low output time of the clamp pulse is set for each characteristic of the attached electronic scope 10 and for each period (video signal period, etc.) within the field period. In step S19, a counter value for measuring the low output time of the clamp pulse is set to a fixed value regardless of the characteristics and period of the electronic scope 10.

  In step S20, measurement of the clamp pulse Low output time is started. In step S21, it is determined whether or not the low output time of the clamp pulse has reached the counter value. If it has not reached, step S21 is repeated. A high output of the clamp hulls is performed to the correction circuit 22.

  In step S23, the counter value used in steps S20 to S23 is reset. In step S24, it is determined whether or not the vertical synchronizing signal has fallen. If not, the process returns to step S20. If there is, the process proceeds to step 25. In step S25, all of the set counter values are reset, and the process proceeds to step S13 (lines are switched).

It is a block diagram of the electronic endoscope system in this embodiment. It is a timing chart which shows a digital component signal and a clamp signal. It is a flowchart which shows the flow in which the length of the Low output period of a clamp pulse is adjusted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic endoscope system 10 Electronic scope 11 Operation part 12 Insertion part 13 Connection part 14 Imaging element 15 1st ROM
19 signal processing circuit 20 image processor 21 pulse generation unit 22 sag correction circuit 23 video signal processing unit 25 scope determination circuit 27 second ROM
29 Timing adjustment circuit 30 Monitor

Claims (3)

A pulse generator that outputs a clamp pulse having a pulse width corresponding to the characteristics of the attached electronic scope and the period during which black level samples can be extracted;
During the period corresponding to the pulse width of the clamp pulse output from the pulse generator, the black level sample is extracted from the luminance signal output from the electronic scope, and the black level is adjusted. A sag correction circuit to perform,
An image processing unit for an electronic endoscope system, comprising: a video signal processing unit that performs image processing on image data acquired by the electronic scope based on a luminance signal output through the sag correction circuit. Processor.   The image processing processor according to claim 1, wherein the pulse generation unit outputs the clamp pulse in consideration of a delay period corresponding to a burst signal. The pulse generation unit, a determination unit for acquiring identification information for identifying the attached electronic scope,
The image processing processor according to claim 1, further comprising: an adjustment unit that sets the pulse width corresponding to the electronic scope to be mounted based on identification information from the determination unit.

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