JPH10290779A - Electronic endoscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an optimum contour emphasis processing corresponding to the luminance of images. SOLUTION: An R contour emphasis amount and emphasis frequency band setting circuit 32r extracts the luminance signals of R source signals by inputting the R source signals from an R signal processing circuit and adding them and the R source signals delayed by a delay circuit 41 by an adder 42 and varies an emphasis frequency band corresponding to the luminance level of the luminance signals by an LUT 43. That is, by enlarging adjustment data Δt so as to lower the emphasis frequency band as the luminance level becomes higher and outputting the adjustment data Δt to R enhance, the R enhance performs the contour emphasis processing corresponding to the luminance level.

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, and more particularly to an electronic endoscope apparatus having a feature in a processing section for contour enhancement.

[0002]

2. Description of the Related Art As means for forming a video signal from an endoscope, an electronic endoscope in which a solid-state imaging device is arranged at the end of the endoscope and a video signal is formed from the output of the imaging device, A detachable camera (hereinafter referred to as an external camera for an endoscope) is attached to the eyepiece of a fiberscope through which a bundle of fibers for observing from the eyepiece to the eyepiece is used to form a video signal from the output signal. There are two types of methods of an external camera for an endoscope, and the contour enhancement in both of the conventional methods is based on red, green, and blue RG from a signal obtained by imaging a subject.
A video signal such as a B color signal or a luminance signal Y is formed, and the same amount of contour enhancement is performed on each of the video signals in the same frequency band. The applicant of the present invention has filed Japanese Patent Application No. 62-271195 in which the amount of contour enhancement is independently variable for each video signal, but in this application, only one frequency band is emphasized. Was.

[0003] Of the subjects in an endoscope, those that require particularly detailed observation include various lesions, blood vessel images, and the inside of a vessel having an unusual hue due to coloring liquid. The color components contained in the subject vary widely,
Also, the color components that best represent the characteristics are different. Therefore, if the edge enhancement amounts of all color signals are made the same as in the conventional case, unnecessary color components are emphasized, and a change in the color component of interest cannot be sufficiently confirmed, so that an appropriate diagnostic effect can be obtained. There is a problem that can not be. Further, when an image of a subject is captured by an endoscope, the frequency band of the video signal is several M
Has the size of Hz. Therefore, the frequency that characterizes the site depends on the site to be observed. In view of this, for example, Japanese Patent Publication No. Hei 7-96011 proposes a video processor for an endoscope capable of appropriately observing a portion of interest of a subject by selectively setting a frequency band for contour enhancement and a contour enhancement amount. ing. The video processor for an endoscope receives a control signal from the contour emphasis control means, and the contour emphasis amount setting means changes the contour emphasis amount, and outputs the changed contour emphasis amount to the contour emphasis means, The band setting means changes the frequency band, and outputs the changed frequency band to the contour emphasizing means,
The contour emphasizing means performs contour emphasis of the video signal based on the contour emphasis amount and the frequency band.

[0004]

However, in the conventional edge enhancement processing, no consideration is given to the brightness of the image. For example, in the case of the edge enhancement processing, it is assumed that a high-luminance portion exists in the image. In addition, since the image enhancement amount is irrelevant to the luminance, the image is emphasized more than necessary, causing a problem that the screen is glaring and the image is unsuitable for observation.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide an electronic endoscope apparatus capable of performing an optimum contour emphasis process in accordance with the luminance of an image.

[0006]

According to the present invention, there is provided an electronic endoscope apparatus provided with an outline emphasis processing means for performing an outline emphasis process on a subject image picked up by a solid-state image sensor. The image processing apparatus includes: a luminance calculating unit that calculates an average luminance of the subject image; and an emphasis amount changing unit that changes an outline emphasis amount of the subject image according to the level of the average luminance.

In the electronic endoscope apparatus according to the present invention, the brightness calculating means calculates an average brightness of the subject image, and the emphasis amount changing means determines an outline emphasis amount of the subject image according to the level of the average brightness. By making the change, it is possible to perform an optimum edge enhancement process according to the luminance of the image.

[0008]

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

FIGS. 1 to 8 relate to a first embodiment of the present invention. FIG. 1 is a configuration diagram showing a configuration of an electronic endoscope apparatus, and FIG. 2 is a main part of the electronic endoscope apparatus of FIG. FIG. 3 is a block diagram showing the configuration of the R contour emphasis amount and emphasis frequency band setting circuit of FIG. 2, FIG. 4 is an explanatory diagram for explaining the operation of the LUT of FIG. 3, and FIG. FIG. 6 is a second explanatory diagram illustrating the operation of the R enhance of FIG. 2, and FIG. 7 is a third explanatory diagram illustrating the operation of the R enhance of FIG. 8 and 9 are flowcharts for explaining white balance processing in the R signal processing circuit, the G signal processing circuit, and the B signal processing circuit in FIG. 2, and FIG. 9 is a flowchart illustrating the R signal processing circuit, the G signal processing circuit, and the B signal in FIG. 13 is a flowchart illustrating a modification of the white balance processing in the processing circuit.

As shown in FIG. 1, an electronic endoscope device 1 according to the present embodiment includes an electronic endoscope 2 and a camera control unit (hereinafter, referred to as a control device) connected to the electronic endoscope 2. CCU) 3 and a CRT monitor 4 for displaying an endoscope image obtained by the electronic endoscope 2.

The electronic endoscope 2 has an elongated insertion portion 5, and a large-diameter operation portion 6 is connected to a rear portion of the insertion portion 5. A universal cord 8 provided with a connector 7 at the rear end extends from a side portion of the operation unit 6, and the connector 7 is connected to the CCU 3. Also,
A distal end portion 9, a bending portion 10, and a flexible portion 11 are sequentially connected to the insertion portion 5 from the distal end side. The bending section 10 can be bent vertically and horizontally by a bending operation knob 12 provided on the operation section 6.

As shown in FIG. 2, the electronic endoscope 2 has an objective lens 20 for image formation accommodated at the distal end side of the elongated insertion portion 5, and is driven by a drive circuit 21 on a focal plane of the objective lens 20. A solid-state imaging device 22 having a color mosaic filter is provided on the incident side where the light is incident.

The imaging signal photoelectrically converted by the solid-state imaging device 22 is amplified by a preamplifier 23, a video signal is extracted by a sample-and-hold circuit (abbreviated as S / H circuit) 24, and is further corrected by a gamma correction circuit 25. After that, it is converted into a digital signal by the A / D converter 26. The video signal that has passed through the A / D converter 26 is input by an RGB matrix circuit 27, and the RGB matrix circuit 27 outputs R, G, and B primary color signals.

R from the RGB matrix circuit 27,
The three primary color signals of G and B are processed by an R signal processing circuit 28r, a G signal processing circuit 28g, and a B signal processing circuit 28b, and then contoured by an R enhance 29r, a G enhance 29g, and a B enhance 29b as described later. Enhancement processing is performed, and the signals are converted into analog signals by D / A converters 30r, 30g, and 30b, respectively, to become R, G, and B color signals.
Output to the RT monitor 4.

The enhancement frequency bands of the R enhance 29r, the G enhance 29g, and the B enhance 29b correspond to an R contour enhancement amount and an enhancement frequency band setting circuit 32r, G, respectively.
The R, G, and B are independently set by the contour emphasis amount and frequency band setting circuit 32g and the B outline emphasis amount and emphasis frequency setting circuit 32b, and the contour emphasis amounts are set to be the same for R, G, and B. I have.

R contour enhancement amount and enhancement frequency band setting circuit 3
2r, the G contour enhancement amount and frequency band setting circuit 32g, and the B contour enhancement amount and enhancement frequency setting circuit 32b have the same circuit configuration.
In the example of r, as shown in FIG. 3, the R original signal from the R signal processing circuit 28r is input, and the R original signal delayed by the delay circuit 41 is added by the adder 42, so that R The luminance signal of the original signal is extracted and the look-up table (hereinafter referred to as LUT) 43 varies the emphasis frequency band according to the luminance level of the luminance signal as shown in FIG. That is, the adjustment data Δt is increased in order to lower the emphasis frequency band as the luminance level increases, and this adjustment data Δt is output to the R enhance 29r, so that R
The enhancer 29r performs a contour emphasis process according to the luminance level.

That is, in the R enhance 29r, FIG.
The input signal as shown in (a) is delayed by the adjustment data Δt as shown in FIGS.
The signal shown in (c) of FIG. 2C which has been delayed by a factor of 2 in place of (b) of FIG.
Is obtained, and this signal is inverted by 図 to calculate an output signal shown in FIG. And this one
When the / 2 inverted signal and the output signal of FIG.
An outline emphasis component shown in FIG. The signal level of this contour emphasis component is set by the R contour emphasis amount and emphasis frequency band setting circuit 32r, and is added to the output signal of FIG. can get.

That is, the adjustment data {
t is calculated by the LUT 43, and the R enhance 29r performs contour enhancement using the adjustment data Δt, that is,
FIG. 6B shows an image signal having a luminance level larger than that of the image signal shown in FIG. 6A, as shown in FIG. 7A, and larger than the adjustment data Δt shown in FIG. 6B. 7
An outline emphasis component is obtained by the adjustment data Δt ′ as shown in FIG. 6B, and the output signal having the outline emphasis as shown in FIG. 6C is applied to the output signal as shown in FIG.
An output signal whose edge is enhanced as shown in FIG. The G enhance 29g and the B enhance 29b operate similarly.

As described above, according to the present embodiment, even if the image in which the high luminance area exists is emphasized, the image can be displayed optimally without glare.

The white balance is set in the R signal processing circuit 28r, the G signal processing circuit 28g, and the B signal processing circuit 28b. Conventionally, the white balance is set because the brightness and color tone of the subject are inappropriate. If you can't, you've set it to be closest to white, but in this case,
In spite of the fact that the white balance has not been set, an image as set is displayed, so that there is a problem that the color tone of a subject such as an organ or blood is displayed differently during actual use.

Therefore, in the present embodiment, as shown in FIG. 8, the R signal processing circuit 28r, the G signal processing circuit 28g, and the B signal processing circuit 28b start the white balance operation in step S1, and in step S2. It is determined whether or not the color has converged to the white color within the specified range. If not converged, the process proceeds to step S3. If converged, the process proceeds to step S4. In step S4, the white balance operation is completed and the white balance setting is completed. In step S3, since the color does not converge to the white color within the specified range, before the setting (that is,
The setting is returned to the white balance state (at the time of last use), and the process proceeds to step S4.

Therefore, when the white balance within the specified range does not converge, the white balance state is set before the setting (that is, at the time of the previous use). Therefore, at least the previous set value can be set. It is possible to solve the problem that the color tone of a subject such as an organ or blood is displayed differently.

In FIG. 8, the processing of step S6 shown in FIG. 9 may be added after step S3.
That is, in step S6, by repeating steps S1 to S6 a predetermined number of times (n times), the white balance may be set in the vicinity of the previously set value, and a more accurate white balance state may be set.

FIGS. 10 to 12 relate to a second embodiment of the present invention. FIG. 10 is a configuration diagram showing a configuration of an R contour enhancement amount and enhancement frequency band setting circuit, and FIG.
12 is an explanatory diagram for explaining the operation of the LUT, and FIG. 12 is an explanatory diagram for explaining the operation of the R enhancement by the second LUT 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 first embodiment, contour emphasis is performed by changing the emphasis frequency band according to the luminance level.
In the present embodiment, in addition to this, the amount of contour enhancement is varied according to the luminance level to enable more optimal enhancement processing.

That is, in the present embodiment, as in the first embodiment, an R contour emphasis amount and emphasis frequency band setting circuit 32r, a G contour emphasis amount and frequency band setting circuit 32g,
The B contour emphasis amount and emphasis frequency setting circuit 32b has the same circuit configuration. If the R outline emphasis amount and emphasis frequency band setting circuit 32r is described as an example, as shown in FIG. The original signal is input and the delay circuit 41
The luminance signal of the R original signal is extracted by adding the R original signal delayed by the adder 42 by the adder 42, and the emphasis frequency band is extracted by the LUT 43 according to the luminance level of the luminance signal as shown in FIG. Make it variable. That is, in order to lower the emphasis frequency band as the luminance level increases, the adjustment data
t, and adjust the adjustment data Δt to R enhance 29
r, the R enhance 29r performs the contour emphasis processing according to the luminance level. The luminance signal of the R original signal is also input to the second LUT 51, and this LUT
11, as shown in FIG. 11, the enhancement amplification amount is reduced as the luminance level is increased in order to reduce the enhancement amount as the luminance level is increased, and the enhancement amplification amount is output to the R enhance 29r together with the adjustment data Δt. .

Then, the R enhancement 29r is obtained by the adjustment data Δt corresponding to the luminance level from the LUT 43 and the enhancement amplification amount corresponding to the luminance level from the LUT 51.
Performs contour enhancement, that is, for an image signal as shown in FIG. 12A having a luminance level larger than that of the image signal with the luminance shown in FIG. 6A, as shown in FIG. The adjustment data $ t 'larger than the adjustment data $ t (Fig. 7
(B) is multiplied by the enhancement amplification amount to obtain an outline emphasis component as shown in FIG.
With respect to the output signal whose edge is enhanced as shown in FIG. 11C, an output signal whose edge is enhanced as shown in FIG.

Therefore, in this embodiment, in addition to the first embodiment in which the emphasis frequency band is made variable in accordance with the luminance level, the emphasis amount is also made variable in accordance with the luminance level, whereby the high luminance area Even if contour enhancement is performed on an existing image, a more optimal observation image can be displayed without causing any glare in the image.

[Supplementary Note] (Supplementary note 1) In an electronic endoscope apparatus provided with an outline emphasis processing means for performing an outline emphasis process on a subject image picked up by a solid-state imaging device, an average luminance of the subject image is calculated. Brightness calculating means (for example, the delay circuit 41 of FIG. 3)
And an adder 42), and frequency variable means (for example, LUT 43 in FIG. 3) for changing the contour emphasis frequency of the subject image in accordance with the level of the average luminance. .

(Supplementary note 2) The frequency varying means decreases the contour emphasis frequency when the luminance level of each pixel of the subject image is higher than the average luminance. Item 2. The electronic endoscope device according to item 1.

(Additional Item 3) The image processing apparatus according to the additional item 1, further comprising an emphasis amount changing unit (for example, LUT 51 in FIG. 10) that changes an outline emphasis amount of the subject image in accordance with the level of the average luminance. Electronic endoscope device.

(Additional Item 4) When the luminance level of each pixel of the subject image is higher than the average luminance, the frequency variable means lowers the outline emphasis frequency and / or the emphasis. The electronic endoscope apparatus according to claim 3, wherein the amount varying means reduces the contour enhancement amount.

(Supplementary Note 5) In an electronic endoscope apparatus provided with an outline emphasis processing means for performing outline emphasis processing on a subject image picked up by a solid-state image pickup device, a brightness calculation for calculating an average brightness of the subject image is performed. Means (eg, FIG. 10)
And an adder 42), and emphasis amount changing means (for example, LUT 51 in FIG. 10) for changing the outline emphasis amount of the subject image according to the level of the average luminance. Electronic endoscope device.

(Additional Item 6) The emphasis amount varying means reduces the outline emphasis amount when the luminance level of each pixel of the subject image is higher than the average luminance. An electronic endoscope apparatus according to additional item 5.

(Supplementary note 7) In an electronic endoscope apparatus provided with white balance processing means for performing white balance processing on a subject image picked up by a solid-state image sensor, the white balance processing means has a predetermined white balance. An electronic endoscope apparatus comprising: returning to a white balance state before white balance processing if the convergence does not reach white within the specified value, and terminating the processing.

[0037]

As described above, according to the electronic endoscope apparatus of the present invention, the luminance calculating means calculates the average luminance of the subject image, and the emphasis amount varying means calculates the average luminance of the subject image according to the level of the average luminance. Since the amount of contour enhancement is changed, there is an effect that optimal contour enhancement processing according to the luminance of the image can be performed.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing a configuration of a main part of the electronic endoscope apparatus of FIG. 1;

FIG. 3 is a configuration diagram showing a configuration of an R contour enhancement amount and enhancement frequency band setting circuit of FIG. 2;

FIG. 4 is an explanatory diagram illustrating the operation of the LUT in FIG. 3;

FIG. 5 is a first explanatory view illustrating the operation of R enhance of FIG. 2;

FIG. 6 is a second explanatory diagram illustrating the operation of the R enhance of FIG. 2;

FIG. 7 is a third explanatory view illustrating the operation of the R enhance of FIG. 2;

8 is an R signal processing circuit, a G signal processing circuit, and a B signal processing circuit shown in FIG.
Flowchart for explaining white balance processing in a signal processing circuit

FIG. 9 illustrates an R signal processing circuit, a G signal processing circuit, and a B signal processing circuit illustrated in FIG. 2;
Flowchart for explaining a modification of white balance processing in a signal processing circuit

FIG. 10 is a configuration diagram showing a configuration of an R contour enhancement amount and enhancement frequency band setting circuit according to a second embodiment of the present invention;

FIG. 11 is an explanatory diagram illustrating the operation of the second LUT in FIG. 10;

FIG. 12 is an explanatory diagram for explaining the function of R enhancement by the second LUT of FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic endoscope apparatus 2 ... Electronic endoscope 3 ... CCU 4 ... CRT monitor 5 ... Insertion part 6 ... Operation part 7 ... Connector 8 ... Universal code 9 ... Tip end part 10 ... Bending part 11 ... Flexible part DESCRIPTION OF SYMBOLS 12 ... Bending operation knob 20 ... Objective lens 21 ... Drive circuit 22 ... Solid-state imaging device 23 ... Preamplifier 24 ... S / H circuit 25 ... Gamma correction circuit 26 ... A / D converter 27 ... Matrix circuit 28r ... R signal processing circuit 28g ... G signal processing circuit 28b ... B signal processing circuit 29r ... R enhance 29g ... G enhance 29b ... B enhance 30r, 30g, 30b ... D / A converter 32r ... R contour emphasis amount and emphasis frequency band setting circuit 32g ... G contour Emphasis amount and emphasis frequency band setting circuit 32b B contour emphasis amount and emphasis frequency band setting circuit 41 Delay circuit 42 Adder 43 LUT

Claims (1)

[Claims] 1. An electronic endoscope apparatus comprising an outline emphasis processing unit for performing an outline emphasis process on a subject image picked up by a solid-state imaging device, comprising: a brightness calculation unit that calculates an average brightness of the subject image; An electronic endoscope apparatus comprising: an emphasis amount changing unit that changes an outline emphasis amount of the subject image according to the level of the average luminance.