JP2009219719A - Endoscope system - Google Patents

Abstract

Even when an appropriate light amount cannot be obtained by automatic light amount control, image quality deterioration of an endoscopic image is prevented.
An object is irradiated with light L from a light source unit 10, and an endoscope image P is acquired by an image pickup device 22. Whether or not automatic control of the light source unit 10 is properly performed by determining whether or not the average luminance value Yav or peak value Ypeak of the endoscopic image P is within the set luminance range Yrg in the light source control means 40 Is judged. If the average luminance value Yav of the endoscopic image P is out of the set luminance range Yrg even after the predetermined period has elapsed, it is determined that appropriate light amount control cannot be performed by the control of the light source unit 10. Then, the coefficient adjustment means 50 adjusts the gain coefficients a, b, and c when performing gain correction based on the average luminance value Yav or peak value Ypeak of the endoscope image P0.
[Selection] Figure 1

Description

  The present invention relates to an endoscope apparatus having a function of automatically controlling the amount of light irradiated to a subject.

Conventionally, when photographing an object in a body cavity in an endoscope apparatus, light emitted from a light source is guided to a distal end portion via a ride guide, and the subject is irradiated with light from the distal end portion. ing. Here, the intensity of light emitted from the light source is automatically adjusted by the endoscope apparatus (see, for example, Patent Document 1). For example, the brightness of an endoscopic image acquired by the image sensor is detected, and the intensity of light emitted from the light source is automatically controlled so that the detected brightness becomes a predetermined brightness.
JP 2007-300972 A

  However, even if the light source unit is controlled to emit a predetermined amount of light, there may be cases where the predetermined amount of light cannot actually be emitted due to hardware limitations of the light source. For example, even if control is performed to increase the light intensity for the light source, the required light quantity may not be obtained due to deterioration over time of the lamp in the light source or partial disconnection of the optical fiber. Alternatively, even if the light source unit is controlled to reduce the light intensity, the light amount may not be sufficiently reduced due to the mechanical performance limit of the diaphragm provided in the light source. In this way, when a desired amount of light is not emitted from the light source, there is a problem that the endoscopic image becomes dark or whiteout occurs and the image quality deteriorates.

  Therefore, an object of the present invention is to provide an endoscope apparatus that can prevent deterioration of image quality even when light of a desired light amount is not emitted from a light source unit under automatic light amount control. Is.

  An endoscope apparatus according to the present invention uses a gain coefficient for a light source unit that emits light to irradiate a subject and an endoscopic image obtained by photographing the subject that has been irradiated with light emitted from the light source unit. A gain correction unit that performs correction, a light source control unit that automatically controls the amount of light emitted from the light source unit to the subject so that the brightness of the endoscope image becomes a preset brightness, Coefficient adjustment means for adjusting the gain coefficient in the gain correction means in accordance with the brightness of the endoscopic image, and the light source control means has the brightness of the endoscope image set in advance by automatic light quantity control. The brightness of the endoscope image when the coefficient adjustment means determines that the brightness of the endoscope image is not a preset brightness in the light source control means. Depending on Those characterized thereby adjusting the emission coefficient.

  Here, the endoscope apparatus may acquire the endoscope image using these component images after acquiring each RGB image separately by the frame sequential method, or the endoscope by the simultaneous method. An image may be acquired.

  The brightness of the endoscopic image may be an average luminance value of the endoscopic image or may be a peak value of luminance in the endoscopic image. Further, the preset brightness may be a predetermined value or a predetermined range.

  In addition, you may have further the noise suppression means which suppresses noise from the endoscope image gain-corrected by the gain correction means. At this time, the noise suppression means may adjust the degree of noise suppression according to the gain coefficient adjusted by the coefficient adjustment means.

The noise suppression means may be any method as long as it performs noise suppression processing on a gain-corrected endoscopic image. For example, the endoscopic image is divided into a plurality of regions, and correction within the divided regions is performed. The pixel value after correction is sh (x, y), the pixel value before correction is g (x, y), the signal obtained by passing the pixel in the divided area through a low-pass filter is glpf (x, y), and the noise suppression strength When the gain which is a decreasing function of k is W (k), noise suppression processing may be performed on the endoscopic image by the above equation (1). In particular, when the gain W is a Wiener filter, the average pixel value in the region is gav, the variance of the pixel values in the region is σ _{(s + n)} ² , and the variance value of the noise component in the region is σ _n ^2. In addition, noise suppression processing by a Wiener filter may be performed on the endoscopic image by the above formula (2). At this time, the coefficient processing means adjusts the noise suppression strength k in Expression (2) according to the gain coefficient.

For example, a noise suppression process according to Expression (1) using a Wiener filter may be performed on an endoscopic image. At this time, the noise suppression means adjusts the coefficient k of the Wiener filter according to the gain coefficient.

  Alternatively, the noise suppression unit may perform coring on the endoscopic image, and may adjust the coring width according to the gain coefficient.

  According to the endoscope apparatus of the present invention, a gain coefficient is used for a light source unit that emits light that irradiates a subject and an endoscope image that is obtained when the subject that is irradiated with light emitted from the light source unit is photographed. Gain correction means for performing gain correction, and light source control means for automatically controlling the amount of light emitted from the light source unit to the subject so that the brightness of the endoscope image becomes a preset brightness. A coefficient adjustment unit that adjusts a gain coefficient in the gain correction unit according to the brightness of the endoscopic image, and the light source control unit is a brightness in which the brightness of the endoscopic image is set in advance by automatic light amount control. When the coefficient adjustment unit determines that the brightness of the endoscopic image is not a preset brightness in the light source control unit, the function of the endoscopic image is determined. Depending on brightness By adjusting the gain coefficient, the endoscopic image becomes darker or brighter by adjusting the gain coefficient even if the light source unit cannot irradiate an appropriate amount of light due to deterioration of the light source unit over time or performance limitations. It is possible to compensate for the deterioration of the image quality such as being too much.

  In addition, it further has a noise suppression means for suppressing noise from the endoscope image whose gain has been corrected by the gain correction means, and the noise suppression means adjusts the degree of noise suppression according to the gain coefficient adjusted by the coefficient adjustment means. When it is, the degree of noise suppression can be adjusted in accordance with the appearance of the noise component due to the adjustment of the gain coefficient, so that it is possible to perform appropriate noise suppression processing on the endoscopic image it can.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a basic configuration of an endoscope apparatus 1 according to an embodiment of the present invention. The endoscope apparatus 1 includes a light source unit 10, a scope 20, and an endoscope image processing apparatus 30, and the operation is controlled by an apparatus controller 60.

  The light source unit 10 emits light for performing observation with an endoscope, and includes a xenon lamp that emits light L and the like. The light source unit 10 is optically connected to the light guide 15 of the scope 20, and the light L emitted from the light source unit 10 enters the light guide 15 and is irradiated onto the subject from the observation window 16.

  The scope 20 includes an imaging optical system 21, an image sensor 22, a CDS / AGC circuit 23, an A / D converter 24, a CCD driving unit 25, a lens driving unit 26, and the like. It is controlled by. The imaging element 22 is made of, for example, a CCD or a CMOS, and obtains an endoscope image P by photoelectrically converting the subject image formed by the imaging optical system 21. For example, a complementary color type having Mg (magenta), Ye (yellow), Cy (cyan), and G (green) color filters or a primary color type having RGB color filters is used as the image pickup element 22. . The operation of the image sensor 22 is controlled by the CCD drive unit 25. When the image pickup device 22 acquires an image (video) signal, a CDS / AGC (correlated double sampling / automatic gain control) circuit 23 samples and amplifies, and an A / D converter 24 outputs from the CDS / AGC circuit 17. The endoscope image P <b> 0 is A / D converted and output to the endoscope image processing device 30.

  The endoscopic image processing device 30 performs image processing of the endoscopic image P0 output from the scope 20, and includes an image acquisition unit 31, a gain correction unit 32, a gamma correction unit 33, a noise suppression unit 34, The light source control means 40, the coefficient adjustment means 50, etc. are provided.

  The image acquisition means 31 is made up of, for example, a DSP (digital signal processor) or the like, and acquires an endoscopic image P imaged by the imaging element 22 of the scope 20. Note that when the image pickup device 22 acquires an endoscope image P0 composed of Mg (magenta), Ye (yellow), Cy (cyan), and G (green), a function of performing color conversion to an endoscope image P0 composed of RGB. have. When the imaging element 22 acquires an endoscopic image P composed of RGB components, the color conversion process is not necessary.

  The gain correction unit 32 performs gain correction on the endoscopic image P0 acquired by the image acquisition unit 31 and outputs a corrected endoscopic image P1. Specifically, the gain correction unit 32 calculates P1r = a · P0, P1g = b · P0, and P1b = c · P0 for each RGB component, and generates an endoscopic image P1. The gamma correction unit 33 outputs an endoscopic image P2 obtained by correcting each pixel value of the endoscopic image P1 based on the gamma curve with respect to the endoscopic image P1 gain-corrected by the gain correction unit 32. .

The noise suppression unit 34 suppresses a noise component included in the endoscopic image P2. Here, reducing the noise without reducing the signal component of the endoscopic image P2 as much as possible can be realized by reducing the high-frequency component. Specifically, after extracting the high frequency component by subtracting the signal glpf (x, y) that has passed through the low-pass filter from the signal g (x, y) of the endoscopic image P2 as in the following equation (1). This is performed by multiplying a gain W (k) of 1.0 or less, which is a decreasing function of the noise suppression strength k.
sh (x, y) = W (k) ・ (g (x, y)-glpf (x, y)) + glpf (x, y) (1)

The noise suppression unit 34 performs noise suppression processing using, for example, a Wiener filter as the gain W. That is, when each pixel value of the endoscopic image P2 is g (x, y), the noise component of the endoscopic image P2 is n (x, y), and the original image is s (x, y),
g (x, y) = s (x, y) + n (x, y)
It can be expressed as. Here, the noise suppression unit 34 divides the endoscopic image P2 into a plurality of regions (for example, 5 × 5 pixels), W is the Wiener filter in the region, and sh (x, y) is the filtered endoscopic image. ), When the pixel average value of the region that is a signal through the low-pass filter is gav (= glpf (x, y)), the endoscopic image sh (x, y) after the filter processing of the above formula (1) Is
sh (x, y) = W (k). (g (x, y) −gav) + gav (1 ′)
It becomes.

On the other hand, the Wiener filter W has a pixel value variance value σ _{(s + n)} ² and a noise component variance value σ _n ² in the endoscope image P.
W (k) = (σ _{(s + n)} ² −k · σ _n ² ) / σ _{(s + n)} ² (2)
It is represented by Note that the variance value σ _n ² of the noise component is determined by the characteristics of the image sensor 22 and is stored in advance. The noise suppression strength k determines the degree of noise suppression processing.

Here, the noise suppression unit 34 divides each RGB component of the endoscopic image P into, for example, 5 × 5 pixel regions, and calculates an average value gav and a variance value σ _{(s + n)} ² for each region. . Then, the noise suppression means 34 obtains the Wiener filter W of (2) using the calculated variance value σ _{(s + n)} ² and the stored variance value σ _n ² . Furthermore, the noise suppression means 34 acquires an endoscope image P3 in which the noise component is suppressed from the endoscope image P according to Expression (1) using the Wiener filter W and the average value gav.

  The synchronization processing unit 35 generates one endoscope image P4 using the color component images of each RGB component acquired by the frame sequential method. Note that when the endoscopic image P is acquired by a method called a so-called frame sequential method in which light of each color of RGB is irradiated at different timings, the above-described synchronization processing is necessary. When the endoscopic image P is acquired by a method called, the synchronization process is unnecessary. Moreover, although the case where the synchronization process by the synchronization processing unit 35 is performed after the noise suppression process by the noise suppression unit 34 is illustrated, the noise suppression process may be performed after the synchronization process is performed.

  The image adjusting unit 36 performs various image processing on the endoscopic image P4 that has been synchronized by the synchronization processing unit 35. For example, inverse gamma correction, gradation adjustment, and the like are performed. The display control means 37 is for displaying an endoscopic image on the display device 3 composed of a liquid crystal display device, a CRT, or the like. The display control means 37 performs, for example, mirror image processing, processing for generating and displaying a mask image from various images, processing for displaying information on the various images as character information, and a function for displaying these simultaneously with the endoscopic image. Have.

  Furthermore, the endoscope image processing apparatus 30 performs light source control means 40 that automatically controls the intensity of light emitted from the light source unit 10 described above (ALC: Auto Light Control), and automatic control by the light source control means 40. And a coefficient adjusting means 50 for compensating the image quality of the endoscopic image P0 when it is not possible to irradiate the light L with an appropriate amount of light. The light source control means 40 calculates an average brightness value Yav indicating the brightness of the endoscope image P0 from the brightness of each pixel of the endoscope image P0 acquired by the image acquisition means 31, and the calculated average brightness value Yav is It has a function of determining whether or not it is a set luminance value Yref indicating a preset brightness. Note that a histogram of the endoscopic image P0 may be calculated when calculating the average luminance value Yav. As shown in FIG. 2, when the average luminance value Yav is deviated from the set luminance value Yref, the light source controller 40 emits light from the light source unit 10 based on the deviation amount between the average luminance value Yav and the set luminance value Yref. The intensity of the light L to be controlled is controlled. Then, an endoscope image P in which the average luminance value Yav as shown in FIG. 3 becomes the set luminance value Yref is acquired.

  Furthermore, the light source control means 40 has a function of determining whether or not the brightness of the endoscopic image P0 has reached a preset brightness by the above-described automatic control of the light amount. Specifically, although the light source control means 40 performs automatic light amount control for a predetermined period or longer, the average luminance value Yav detected from the endoscopic image P deviates from the set luminance value Yref. At this time, it is determined that the light source unit 10 does not adjust the light amount of the light L appropriately.

  In addition, although the case where the average luminance value Yav is used as the brightness of the endoscopic image P0 is illustrated, the luminance peak value Ypeak in the endoscopic image P0 may be used. Even in this case, it is determined whether or not the luminance peak value Ypeak is deviated from the set maximum luminance value Ymax. Further, although the case where the set brightness value Yref is used as the preset brightness is illustrated, it may be set like a predetermined brightness value range Yrg in which the value has a width.

  The coefficient adjusting unit 50 in FIG. 1 adjusts the gain coefficients a, b, and c in the gain correcting unit 32 when the light source control unit 40 determines that the adjustment of the light amount of the light L is not appropriate. Specifically, the coefficient adjusting unit 50 calculates gain coefficients a, b, and c such that the average luminance value Yav becomes the set luminance value Yref. The gain correction unit 32 performs gain correction using the adjusted gain coefficients a, b, and c. When the light amount control is performed so that the average luminance value Yav of the endoscopic image P0 is a value within the set luminance range Yrg, the coefficient adjusting unit 50 sets preset gain coefficients a, b, and c that are set in advance. Output and gain correction is performed.

  As described above, even when the amount of the light L applied to the subject is inappropriate and the image quality of the endoscopic image P is deteriorated, the deterioration of the image quality can be prevented by the gain correction. it can. For example, even if the light L of an appropriate amount of light L cannot be irradiated from the scope 20 due to partial disconnection of the light guide 15 or deterioration of the light source unit 10 with time, the gain coefficient is even when the entire endoscope image P0 becomes dark. Correction that brightens the endoscope image P0 is performed by performing adjustment to increase a, b, and c. On the contrary, there is a case where the light quantity stop in the light source unit 10 needs to reduce the light quantity to 1/1000, but the light quantity diaphragm range is 1 to 1/100 and the light quantity cannot be sufficiently reduced. is there. At this time, the coefficient adjusting unit 50 performs correction to reduce the gain coefficients a, b, and c. Thus, an endoscopic image that facilitates image diagnosis can be provided by adjusting the gain coefficients a, b, and c according to the state of the light source unit 10.

  Furthermore, the coefficient adjusting unit 50 has a function of adjusting the noise suppression strength k in the noise suppressing unit 34 according to the calculated gain coefficients a, b, and c. Specifically, the coefficient adjusting unit 50 stores the relationship of the noise suppression strength k to the gain coefficient as shown in FIG. 4A, and the coefficient adjusting unit 50 sets the calculated gain coefficients a, b, and c to the values. Accordingly, the noise suppression strength k is determined. As shown in FIG. 4B, the Wiener filter W decreases as the noise suppression strength k increases, meaning that noise suppression is not performed when k = 0 (the above formula (1), (See (2)). Then, the degree of noise suppression in the noise suppression unit 34 changes. For example, when the gain coefficients a, b, and c are large, noise components are also emphasized. Therefore, the noise suppression strength k is increased to increase the degree of noise suppression. To do. On the other hand, when the gain coefficients a, b, and c are small, the noise suppression strength k is decreased in order to reduce the reduction in sharpness due to suppression of noise components. Thereby, the noise suppression process matched with the characteristic of the endoscopic image can be performed.

  Hereinafter, an operation example of the endoscope apparatus will be described with reference to FIGS. 1 to 4. First, when imaging is started by the endoscope apparatus 1, light L is emitted from the light source unit 10, and the light L is emitted from the scope 20 to the subject via the light guide 15. The endoscope image P is acquired by the imaging element 22 in a state where the subject is irradiated with the light L, and is acquired by the image acquisition unit 31 of the endoscope image processing apparatus 30.

  At this time, the light source control means 40 determines whether the average luminance value Yav or peak value Ypeak of the endoscopic image P is within the set luminance range Yrg, so that automatic control of the light source unit 10 is appropriately performed. It is determined whether or not. If the average luminance value Yav of the endoscopic image P is out of the set luminance range Yrg even after the predetermined period has elapsed, it is determined that appropriate light amount control cannot be performed by the control of the light source unit 10.

  Then, the coefficient adjustment means 50 adjusts the gain coefficients a, b, and c based on the average luminance value Yav or peak value Ypeak of the endoscope image P0. Then, gain correction is performed using the gain coefficients a, b, and c adjusted by the gain correction means 32. Further, the coefficient adjusting unit 50 adjusts the noise suppression strength k based on the values of the gain coefficients a, b, and c, and the noise suppressing process is performed by the noise suppressing unit 34.

  As described above, even when the light source unit 10 cannot irradiate the subject with an appropriate amount of light L due to deterioration of the light source unit 10 over time, function limitation, or the like, the gain coefficient a, b, c is adjusted to perform internal viewing. It is possible to compensate for image quality deterioration such that the mirror image P becomes dark or too bright. Furthermore, by adjusting the degree of noise suppression processing in accordance with the adjustment of the gain coefficients a, b, and c, it is possible to prevent image quality deterioration due to, for example, enhancement of noise components.

  FIG. 5 is a block diagram showing another embodiment of the noise suppressing means in the endoscope apparatus of the present invention. The endoscope apparatus 100 will be described with reference to FIG. In the endoscopic device 100 of FIG. 5, parts having the same configuration as the endoscopic device 1 of FIG. 1 are denoted by the same reference numerals and description thereof is omitted. The endoscope apparatus 100 of FIG. 5 is different from the endoscope apparatus 1 of FIG. 1 in that it has a contour emphasizing unit 134 that performs contour emphasis processing on the endoscopic image P.

  The contour emphasizing unit 134 performs processing for enhancing the contour of the subject in the endoscopic image P, and has an input-output characteristic as shown in FIG. 6, for example. In particular, when the pixel value of the endoscopic image P input to the contour emphasizing means 134 is of the coring width | TH |, zero is output as the pixel value, and for pixel values other than the coring width | TH | The pixel value is output in accordance with the characteristics shown in FIG. That is, the pixel value within the coring width | TH | constituting the granular noise component becomes zero and functions as noise suppression means.

  Here, the coring width | TH | is adjusted by the coefficient adjusting means 50. That is, as shown in FIG. 7, the coefficient adjusting means 50 stores the relationship of the coring width TH with respect to the gain coefficients a, b, and c. Based on the adjusted values of the gain coefficients a, b, and c. Adjust the coring width TH. In FIG. 7, the coefficient adjusting means 50 sets the coring width TH = 0 for the gain coefficients a, b, c ≦ 1.0, and the coring width TH for 1.0 ≦ a, b, c ≦ Gref. Linearly increases, and the coring width TH is adjusted to be constant when Gref ≦ a, b, and c.

  Thus, even when the coring process in the contour enhancement process is functioned as a noise suppression unit, the degree of noise suppression can be adjusted according to the gain coefficients a, b, and c, and an appropriate noise suppression process can be performed. Can be applied.

  According to the above-described embodiment, the gain coefficients a, b, and c with respect to the endoscope image P0 when the light source unit 10 that emits the light L and the subject irradiated with the light emitted from the light source unit 10 are photographed. And the gain correction means 32 for performing gain correction using the, and the light quantity of the light L emitted from the light source unit 10 to the subject automatically so that the brightness of the endoscope image P0 becomes a preset brightness. A light source control means 40 for controlling, and a coefficient adjustment means 50 for adjusting the gain coefficients a, b, and c in the gain correction means in accordance with the brightness of the endoscope image P0. It has a function of determining whether or not the brightness of the endoscope image P0 has become a preset brightness, and the coefficient adjusting means 50 determines whether the brightness of the endoscope image is preset in the light source control means 40. Set When it is determined that the brightness is not bright, by adjusting the gain coefficient according to the brightness of the endoscopic image P0, it is not possible to irradiate an appropriate amount of light from the light source unit 10 due to deterioration of the light source unit 10 over time, functional restrictions, etc. Even so, it is possible to compensate for image quality degradation such that the endoscopic image P becomes darker or brighter by adjusting the gain coefficients a, b, and c.

  The gain correction unit 32 further includes noise suppression units 34 and 134 that suppress noise from the endoscope image P that has been gain-corrected, and the noise suppression units 34 and 134 are gain coefficients a adjusted by the coefficient adjustment unit 50. When adjusting the degree of noise suppression according to b, c, adjust the degree of noise suppression in accordance with the appearance of noise components due to the adjustment of gain coefficients a, b, c. Therefore, an appropriate noise suppression process can be performed on the endoscopic image P.

  The embodiment of the present invention is not limited to the above embodiment. In the above embodiment, the case where the noise suppression process is performed before the synchronization process is illustrated, but the noise suppression process may be performed both before and after the synchronization process. In this case, noise processing by a Wiener filter and noise suppression processing by coring processing may be performed before and after the synchronization processing.

The block diagram which shows preferable embodiment of the endoscope apparatus of this invention The figure which shows the histogram before the gain correction | amendment with respect to the endoscope image P0 of FIG. The figure which shows the histogram after gain correction with respect to the endoscope image P0 of FIG. 1 is a graph showing the relationship between the gain coefficient and the noise suppression strength in the coefficient adjusting means of FIG. FIG. 1 is a graph showing the relationship between the noise suppression strength and the size of the Wiener filter in the coefficient adjustment unit of FIG. The block diagram which shows another embodiment of the endoscope apparatus of this invention The graph which shows the input-output characteristic in the outline emphasis means of FIG. 5 is a graph showing the relationship between the gain coefficient and the noise suppression strength in the coefficient adjusting means of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Endoscope apparatus 10 Light source unit 30 Endoscope image processing apparatus 31 Image acquisition means 32 Gain correction means 34 Noise suppression means 35 Synchronization processing means 40 Light source control means 50 Coefficient adjustment means 134 Contour emphasis means (noise suppression means) )
a, b, c Gain coefficient k Noise suppression intensity L Light P Endoscopic image TH Coring width

Claims (5)

A light source unit that emits light to irradiate the subject;
Gain correction means for performing gain correction using a gain coefficient for the endoscopic image when the subject irradiated with the light emitted from the light source unit is photographed;
Light source control means for automatically controlling the amount of the light emitted from the light source unit to the subject so that the brightness of the endoscopic image becomes a preset brightness;
Coefficient adjustment means for adjusting the gain coefficient in the gain correction means according to the brightness of the endoscopic image,
The light source control means has a function of determining whether or not the brightness of the endoscopic image has become a preset brightness by the automatic control of the light amount,
When the coefficient adjustment unit determines that the brightness of the endoscopic image is not a preset brightness in the light source control unit, the gain coefficient is adjusted according to the brightness of the endoscopic image. An endoscope apparatus characterized by being a thing.   A noise suppression unit that suppresses noise from the endoscope image that has been gain-corrected by the gain correction unit is further included, and the noise suppression unit is a degree of noise suppression according to the gain coefficient adjusted by the coefficient adjustment unit. An endoscopic device characterized by adjusting the angle. The noise suppression means divides the endoscopic image into a plurality of regions, sh (x, y) is a pixel value after correction in the divided region, and g (x, y) is a pixel value before correction. When the signal obtained by passing the pixels in the divided region through a low-pass filter is glpf (x, y) and the gain that is a decreasing function of the noise suppression strength k is W (k), the following equation (1) The endoscope apparatus according to claim 2, wherein a noise suppression process is performed on the endoscopic image.
sh (x, y) = W (k) ・ (g (x, y)-glpf (x, y)) + glpf (x, y) (1) The gain W is a Wiener filter represented by the following formula (2) when the variance of pixel values in the region is σ _{(s + n)} ² and the variance of noise components in the region is σ _n ² , 4. The endoscope apparatus according to claim 3, wherein the coefficient processing means adjusts the noise suppression strength k of the Wiener filter of Expression (2) according to the gain coefficient.
W = (σ _{(s + n)} ² −k · σ _n ² ) / σ _{(s + n)} ² (2)   The noise suppression unit includes a contour enhancement unit that performs a contour enhancement process and a coring process on the endoscope image, and the coefficient adjusting unit adjusts a coring width according to the gain coefficient. The endoscope apparatus according to claim 2.

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