JPWO2017022324A1 - Endoscopy system signal processing method and endoscope system - Google Patents

Abstract

The image signal processing method according to the present invention includes a video signal, a first signal including a contrast component signal, and a second signal including a component signal other than the component signal included in the first signal among the component signals of the video signal. A division step for dividing the input signal into components, a brightness adjustment step for performing a brightness adjustment process on the second signal among the component signals divided in the division step, the first signal divided in the division step, and the brightness And a synthesis step of synthesizing the second signal after the brightness adjustment in the height adjustment step.

Description

  The present invention relates to an image signal processing method, an image signal processing apparatus, and an image signal processing program for performing brightness adjustment processing on an input image.

  Conventionally, a technique for adjusting the brightness of an input image by performing brightness adjustment processing such as γ correction processing on the input image is known. In the γ correction process, correction is performed to brighten a dark part having a small luminance value in the input image. As such γ correction processing, a technique is disclosed in which a γ coefficient is set according to color and γ correction according to each color is performed (see, for example, Patent Document 1).

JP 2009-118898 A

  However, in the conventional γ correction processing, correction for increasing the brightness of the dark part is performed, while correction for compressing the contrast is performed for the bright part having a large luminance value. For this reason, when the conventional γ correction processing is performed on the input image, although the brightness of the input image is improved, there is a problem that an image having a deteriorated contrast as compared with the input image can be obtained.

  The present invention has been made in view of the above, and provides an image signal processing method, an image signal processing apparatus, and an image signal processing program capable of adjusting brightness while suppressing deterioration of contrast. Objective.

  In order to solve the above-described problems and achieve the object, an image signal processing method according to the present invention includes a video signal, a first signal including a contrast component signal, and the first signal among the component signals of the video signal. A division step of dividing the second signal including a component signal other than the component signal included in the first signal, and a brightness for performing a brightness adjustment process on the second signal among the component signals divided in the division step And a synthesis step of synthesizing the first signal divided in the division step and the second signal after the brightness adjustment in the brightness adjustment step. To do.

  In the image signal processing method according to the present invention, in the above invention, the video signal includes a plurality of color components, and the division step, the brightness adjustment step, and the synthesis step are independent for each color component. Signal processing is performed.

  In the image signal processing method according to the present invention as set forth in the invention described above, in the brightness adjustment step, in the brightness value of the second signal, a brightness value smaller than a threshold value is increased and a brightness value equal to or greater than the threshold value is set. A brightness adjustment process is performed on the second signal by setting the same magnification.

  The image signal processing method according to the present invention is characterized in that, in the above invention, the brightness adjustment step adaptively adjusts the brightness based on a luminance value of the second signal.

  The image signal processing method according to the present invention further includes a dimming signal generation step for generating a dimming signal based on the synthesized image signal synthesized by the synthesis step. To do.

  In the image signal processing apparatus according to the present invention, in the above invention, the video signal is a first signal including a contrast component signal, and a component signal other than the component signal included in the first signal among the component signals of the video signal. A division unit that divides the signal into a second signal including a component signal; a brightness adjustment unit that performs a brightness adjustment process on the second signal among the component signals divided by the division unit; and the division unit. And a combining unit that combines the divided first signal and the second signal after brightness adjustment by the brightness adjustment unit.

  In the image signal processing program according to the present invention, in the above invention, the video signal is a first signal including a contrast component signal, and a component signal other than the component signal included in the first signal among the component signals of the video signal. A division procedure for dividing the second signal including a component signal; a brightness adjustment procedure for performing a brightness adjustment process on the second signal among the component signals divided by the division procedure; and the division procedure. And a synthesizing procedure for synthesizing the second signal after the brightness adjustment in the brightness adjustment procedure and the second signal after the brightness adjustment in the brightness adjustment procedure.

  According to the present invention, it is possible to adjust brightness while suppressing deterioration of contrast.

FIG. 1 is a diagram showing a schematic configuration of an endoscope system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of the endoscope system according to the embodiment of the present invention. FIG. 3 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, and a diagram for explaining brightness adjustment processing performed by the brightness adjustment unit on the base component. is there. FIG. 4 is a flowchart showing an image signal processing method performed by the processing apparatus according to the embodiment of the present invention. FIG. 5 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, and shows the relative intensity of the input image and the base component image at each pixel position on a certain pixel line. FIG. FIG. 6 is a diagram for explaining the image signal processing method by the endoscope system according to the embodiment of the present invention, and is a diagram showing the relative intensity of the detail component at each pixel position on a certain pixel line. . FIG. 7 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, in which an input image at each pixel position on a pixel line and a base component image before brightness adjustment are illustrated. FIG. 6 is a diagram illustrating relative intensities of base component images after brightness adjustment. FIG. 8 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, in which an input image at each pixel position on a certain pixel line and conventional brightness adjustment are performed. It is a figure which shows the relative intensity | strength of an image and the image which performed the brightness adjustment of this invention, respectively.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described. In the embodiment, a medical endoscope system that captures and displays an image in a subject such as a patient will be described as an example of a system including an image signal processing device according to the present invention. Moreover, this invention is not limited by this embodiment. Furthermore, in the description of the drawings, the same portions will be described with the same reference numerals.

  FIG. 1 is a diagram showing a schematic configuration of an endoscope system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of the endoscope system according to the present embodiment.

  An endoscope system 1 shown in FIGS. 1 and 2 includes an endoscope 2 that captures an in-vivo image of a subject by inserting a tip portion into the subject, and illumination light emitted from the tip of the endoscope 2. And a processing device 3 that performs predetermined signal processing on the image signal captured by the endoscope 2 and controls the overall operation of the endoscope system 1. And a display device 4 for displaying the in-vivo image generated by the signal processing.

  The endoscope 2 includes an insertion portion 21 having an elongated shape having flexibility, an operation portion 22 that is connected to a proximal end side of the insertion portion 21 and receives input of various operation signals, and an insertion portion from the operation portion 22. And a universal cord 23 that includes various cables that extend in a direction different from the direction in which 21 extends and are connected to the processing device 3 (including the light source unit 3a).

  The insertion unit 21 receives a light and performs photoelectric conversion to generate a signal to generate a signal. The insertion unit 21 includes an image pickup element 244 in which pixels are arranged in a two-dimensional shape, and a bendable portion formed by a plurality of bending pieces. And a long flexible tube portion 26 connected to the proximal end side of the bending portion 25 and having flexibility. The insertion unit 21 uses the image sensor 244 to image a subject such as a living tissue that is inserted into the subject and is not reachable by external light.

  The tip portion 24 is configured by using a glass fiber or the like, and forms a light guide path for light emitted from the light source portion 3a, an illumination lens 242 provided at the tip of the light guide 241, and condensing optics. And an image sensor 244 that is provided at an image forming position of the optical system 243, receives light collected by the optical system 243, photoelectrically converts the light into an electrical signal, and performs predetermined signal processing.

  The optical system 243 is configured using one or a plurality of lenses, and has an optical zoom function for changing the angle of view and a focus function for changing the focus.

  The image sensor 244 photoelectrically converts light from the optical system 243 to generate an electrical signal (image signal). Specifically, in the imaging element 244, a plurality of pixels each having a photodiode that accumulates electric charge according to the amount of light, a capacitor that converts electric charge transferred from the photodiode into a voltage level, and the like are arranged in a matrix, A light receiving unit 244a in which each pixel photoelectrically converts light from the optical system 243 to generate an electric signal, and an electric signal generated by a pixel arbitrarily set as a reading target among a plurality of pixels of the light receiving unit 244a is sequentially read out And a reading unit 244b for outputting as an imaging signal. The light receiving unit 244a is provided with a color filter, and each pixel receives light in one of the wavelength bands of the color components of red (R), green (G), and blue (B). The image sensor 244 controls various operations of the distal end portion 24 in accordance with the drive signal received from the processing device 3. The image sensor 244 is realized by using, for example, a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor.

  The operation unit 22 includes a bending knob 221 that bends the bending unit 25 in the vertical direction and the left-right direction, a treatment tool insertion unit 222 that inserts a treatment tool such as a biological forceps, an electric knife, and an inspection probe into the subject, and a processing device. 3, a plurality of switches 223 that are operation input units for inputting operation instruction signals of peripheral devices such as air supply means, water supply means, and screen display control. The treatment tool inserted from the treatment tool insertion portion 222 is exposed from the opening (not shown) via the treatment tool channel (not shown) of the distal end portion 24.

  The universal cord 23 includes at least a light guide 241 and a collective cable 245 in which one or a plurality of signal lines are collected. The collective cable 245 is a signal line for transmitting an image signal, a signal line for transmitting a drive signal for driving the image sensor 244, information including unique information regarding the endoscope 2 (image sensor 244), and the like. Including a signal line for transmitting and receiving. In the present embodiment, the description will be made assuming that an electrical signal is transmitted using a signal line. However, an optical signal may be transmitted, or the endoscope 2 and the processing device 3 may be connected by wireless communication. A signal may be transmitted between them.

  Next, the configuration of the processing device 3 will be described. The processing device 3 includes an imaging signal acquisition unit 31, a division unit 32, a brightness adjustment unit 33, a synthesis unit 34, a display image generation unit 35, an input unit 36, a storage unit 37, and a control unit 38. . Note that the image signal processing apparatus according to the present invention includes at least a dividing unit 32, a brightness adjusting unit 33, and a combining unit 34.

The imaging signal acquisition unit 31 receives the imaging signal output from the imaging element 244 from the endoscope 2. The imaging signal acquisition unit 31 performs noise removal, A / D conversion, and synchronization processing (for example, performed when an imaging signal for each color component is obtained using a color filter or the like) for the acquired imaging signal. Apply signal processing. The imaging signal acquisition unit 31 generates an input image signal S _C including an input image to which RGB color components are given by the signal processing described above. The imaging signal acquisition unit 31 inputs the generated input image signal S _C to the dividing unit 32 and inputs to the storage unit 37 for storage.

Dividing unit 32 obtains an input image signal S _C from the imaging signal acquisition unit 31 is divided into a weak component and component having a strong visual correlation. The division process can be performed using, for example, the technique (Retinex theory) described in Lightness and retinex theory, EHLand, JJ McCann, Journal of the Optical Society of America, 61 (1), 1-11 (1971). . In the division processing based on the Retinex theory, the visually weakly correlated component corresponds to the illumination light component of the object and is generally called a base component. On the other hand, a visually strongly correlated component is a component corresponding to the reflectance of an object, and is generally called a detail component. The detail component is a component obtained by dividing the signal constituting the image by the base component. The detail component includes a contour component (edge) component of the object and a contrast component such as a texture component. The dividing unit 32 inputs a signal including a base component as a component signal (second signal, hereinafter referred to as “base component signal S _B ”) to the brightness adjusting unit 33 and a signal (first signal) including a detail component as a component signal. 1 signal (hereinafter referred to as “detail component signal S _D ”) is input to the synthesis unit 34. In addition, when the input image signal of each color component of RGB is input, the division unit 32 performs a division process on each color component signal. In the subsequent signal processing, each color component is processed.

  The component division processing by the dividing unit 32 is performed using, for example, the edge-aware filtering technique described in Temporally Coherent Local Tone Mapping of HDR Video, TOAydin, et al., ACM Transactions on Graphics, Vol 33, November 2014. be able to. Further, the dividing unit 32 may divide the spatial frequency into a plurality of frequency bands.

Brightness adjustment unit 33, out of the divided component signal by dividing unit 32 performs brightness adjustment processing on the base component signal S _B. Specifically, the brightness adjustment unit 33 refers to the relation table stored in the storage unit 37 and performs gain-up processing for increasing the low luminance value based on the luminance value at each pixel position. Note that the brightness adjustment unit 33 may perform gain-up processing by performing arithmetic processing on the input base component signal. The brightness adjustment unit 33 inputs the base component signal S _B ′ after the brightness adjustment processing to the synthesis unit 34.

The synthesizer 34 synthesizes the detail component signal _SD divided by the divider 32 and the base component signal S _B ′ subjected to the brightness adjustment processing by the brightness adjuster 33. The synthesizer 34 synthesizes the detail component signal S _D and the base component signal S _B ′ to generate a synthesized image signal S _S that has been subjected to gain adjustment processing only for the base component that is visually weakly correlated. To do. The synthesizer 34 inputs the generated synthesized image signal S _S to the display image generator 35.

The display image generation unit 35 performs signal processing on the combined image signal S _S generated by the combining unit 34 so as to be a signal in a form that can be displayed on the display device 4, and generates a display image signal _ST . Generate. When the input signal is divided into RGB color components, an interpolation process is performed on each color component to generate an image signal in which the RGB color component is added to each pixel position. The display image generation unit 35 outputs the generated image signal _ST to the display device 4.

  The input unit 36 is realized using a keyboard, a mouse, a switch, and a touch panel, and receives input of various signals such as an operation instruction signal that instructs the operation of the endoscope system 1. The input unit 36 may include a portable terminal such as a switch provided in the operation unit 22 or an external tablet computer.

  The storage unit 37 stores various programs for operating the endoscope system 1 and data including various parameters necessary for the operation of the endoscope system 1. Further, the storage unit 37 stores identification information of the processing device 3. Here, the identification information includes unique information (ID) of the processing device 3, model year, specification information, and the like.

  The storage unit 37 includes a brightness adjustment information storage unit 371 that stores brightness adjustment information related to the relationship of luminance values related to input and output used when the brightness adjustment unit 33 performs brightness adjustment processing. FIG. 3 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, and a diagram for explaining brightness adjustment processing performed by the brightness adjustment unit on the base component. is there. FIG. 3 shows an example in which the maximum value set for the input luminance value is normalized to 1. The brightness adjustment information storage unit 371 stores, for example, a graph indicating the relationship between the relative output brightness value and the relative output brightness value as brightness adjustment information as illustrated in FIG. The brightness adjustment unit 33 refers to the graph shown in FIG. 3, and when the luminance value is relatively small with respect to the input signal, the luminance adjustment unit 33 increases the luminance value to increase the relative luminance value. When the value is large, brightness adjustment processing is performed so that the magnification is the same. For example, in FIG. 3, the threshold value for the input luminance value is set to about 0.4, the output luminance value is increased when the input luminance value (relative value) is smaller than the threshold value, and the output luminance when the input luminance value is equal to or higher than the threshold value. Adjustment processing is performed to make the value equal to the input luminance value.

  The storage unit 37 stores various programs including an image signal processing program for executing the image signal processing method of the processing device 3. Various programs can be recorded on a computer-readable recording medium such as a hard disk, a flash memory, a CD-ROM, a DVD-ROM, or a flexible disk and widely distributed. The various programs described above can also be obtained by downloading via a communication network. The communication network here is realized by, for example, an existing public line network, a LAN (Local Area Network), a WAN (Wide Area Network) or the like, and may be wired or wireless.

  The storage unit 37 having the above configuration is realized by using a ROM (Read Only Memory) in which various programs are installed in advance, a RAM (Random Access Memory) storing a calculation parameter and data of each process, a hard disk, and the like. Is done.

  The control unit 38 is configured using a CPU (Central Processing Unit) or the like, and performs drive control of each component including the image sensor 244 and the light source unit 3a, input / output control of information with respect to each component, and the like. The control unit 38 refers to control information data (for example, read timing) for imaging control stored in the storage unit 37, and uses the imaging signal as a drive signal via a predetermined signal line included in the collective cable 245. To 244.

  Further, the control unit 38 detects the brightness based on the image (for example, the synthesized image) based on the acquired imaging signal, sets the exposure amount, and the light emission amount (intensity) corresponding to the set exposure amount. And a dimming signal indicating the shutter opening time.

  Next, the configuration of the light source unit 3a will be described. The light source unit 3 a includes an illumination unit 301 and an illumination control unit 302. Under the control of the illumination control unit 302, the illumination unit 301 sequentially switches and emits illumination light with different exposure amounts to the subject (subject). The illumination unit 301 includes a light source 301a and a light source driver 301b.

  The light source 301a is configured using an LED light source that emits white light, one or a plurality of lenses, and the like, and emits light (illumination light) by driving the LED light source. Illumination light generated by the light source 301 a is emitted from the tip of the tip 24 toward the subject via the light guide 241. The light source 301a may be configured by using a red LED light source, a green LED light source, and a blue LED light source to emit illumination light. The light source 301a may be a laser light source or a lamp such as a xenon lamp or a halogen lamp.

  The light source driver 301b causes the light source 301a to emit illumination light by supplying a current to the light source 301a under the control of the illumination control unit 302.

  The illumination control unit 302 controls the amount of power supplied to the light source 301a and the drive timing of the light source 301a based on a control signal (dimming signal) from the control unit 38.

The display device 4 displays the display image corresponding to the image signal S _T of the processing unit 3 via the video cable (display image generation unit 35) is generated. The display device 4 is configured using a monitor such as liquid crystal or organic EL (Electro Luminescence).

In the endoscope system 1 described above, the dividing unit 32 divides the component included in the imaging signal into two component signals based on the imaging signal input to the processing device 3, and the brightness adjusting unit 33 Then, brightness adjustment processing is performed on one of the divided component signals, and the combining unit 34 combines the component signal after the brightness adjustment with the other component signal, and a display image generating unit 35. but to generate an image signal S _T which has been subjected to signal processing for display based on the combined signal, the display device 4 displays the display image based on the image signal S _T.

FIG. 4 is a flowchart showing an image signal processing method performed by the processing apparatus according to the embodiment of the present invention. The following description is based on the assumption that each unit operates under the control of the control unit 38. When the imaging signal acquisition unit 31 acquires an imaging signal from the endoscope 2 (step S101: Yes), an image to which red (R), green (G), and blue (B) color components are added by signal processing is displayed. An input image signal S _C including this is generated and input to the dividing unit 32. On the other hand, when the imaging signal is not input from the endoscope 2 (step S101: No), the imaging signal acquisition unit 31 repeats the input confirmation of the imaging signal.

Dividing unit 32, the input image signal S _C is input, divide the input image signal S _C to the detail component signal and the base component signal (step S102: dividing step). Dividing section 32 receives an input to the base component signal S _B brightness adjustment portion 33 produced by the above-mentioned division processing, and inputs the detail component signal S _D to the combining unit 34.

FIG. 5 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, and shows the relative intensity of the input image and the base component image at each pixel position on a certain pixel line. FIG. FIG. 6 is a diagram for explaining the image signal processing method by the endoscope system according to the embodiment of the present invention, and is a diagram showing the relative intensity of the detail component image at each pixel position on a certain pixel line. is there. The input image is an image corresponding to the input image signal S _C, the base component image is an image corresponding to the base component signal S _B. The pixel lines shown in FIGS. 5 and 6 are the same pixel line, and indicate the relative intensities at the positions of the 200th to 1000th pixels in the pixel line. FIG. 5 shows an example in which the maximum luminance value of the input image is normalized to 1. FIG. 6 shows an example in which the maximum luminance value of the detail component is normalized to 1.

  As shown in FIG. 5, it can be seen that the low-frequency component is extracted from the luminance change of the input image. This corresponds to a visually weakly correlated component (object illumination light component). On the other hand, the detail component is a component obtained by excluding the base component from the luminance change of the input image as shown in FIG. This corresponds to a visually strong component (a component corresponding to the reflectance of the object).

Then, the brightness adjustment unit 33 performs brightness adjustment processing on the inputted base component signal S _B (step S103: brightness adjustment step). Specifically, the brightness adjusting unit 33 refers to the graph of the relative input luminance value and a relative output intensity values as shown in FIG. 3, adjust the brightness for the input luminance value of the base component signal S _B To do. The brightness adjustment unit 33 inputs the base component signal S _B ′ after the brightness adjustment processing to the synthesis unit 34.

  FIG. 7 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, in which an input image at each pixel position on a pixel line and a base component image before brightness adjustment are illustrated. FIG. 6 is a diagram illustrating relative intensities of base component images after brightness adjustment. The pixel line shown in FIG. 7 is the same pixel line as the pixel line shown in FIG. FIG. 7 shows an example in which the maximum luminance value of the input image is normalized to 1.

As shown in FIG. 7, the base component image corresponding to the base component signal S _B ′ after brightness adjustment has a relatively large relative intensity as a whole. In particular, a luminance value with a smaller relative intensity has a larger luminance value. Adjustment processing is performed. The brightness adjustment unit 33 performs the brightness adjustment process only on the base component signal S _B , so that the detail component in the input image signal S _C can be held.

When the detail component signal _SD is input from the divider 32 and the brightness-adjusted base component signal S _B ′ is input from the brightness adjuster 33, the synthesizer 34 receives the detail component signal _SD and the base component. The signal S _B ′ is synthesized to generate a synthesized image signal S _S (step S104: synthesis step). The synthesizer 34 inputs the generated synthesized image signal S _S to the display image generator 35.

  FIG. 8 is a diagram for explaining an image signal processing method by the endoscope system according to the embodiment of the present invention, in which an input image at each pixel position on a certain pixel line and conventional brightness adjustment are performed. It is a figure which shows the relative intensity | strength of an image and the image which performed the brightness adjustment of this invention, respectively. The pixel lines shown in FIG. 8 are the same pixel lines as the pixel lines shown in FIGS. FIG. 8 shows an example in which the maximum luminance value of the image after brightness adjustment is normalized to 1.

As shown in FIG. 8, a conventional brightness adjustment, that is, an image that has been subjected to conventional γ correction, and a composite image signal S _S that has been subjected to the brightness adjustment of the present invention, that is, the brightness adjustment for only the base component. for both images corresponding combined image, the relative intensities are higher for the input image corresponding to the input image signal S _C.

Here, the composite image corresponding to the composite image signal S _S subjected to the brightness adjustment of the present invention has contrast information, that is, a luminance change included in the input image, as compared with the image subjected to the conventional brightness adjustment. You can see that it is not lost. In contrast to the contrast difference, in the conventional brightness adjustment process (γ correction process), correction is performed such that the contrast is compressed for a bright part having a large luminance value. It is generated by dividing the base component and the detail component and adjusting the brightness only for the base component.

When the synthesized image signal S _S is input from the synthesizing unit 34, the display image generating unit 35 performs signal processing so that the synthesized image signal S _S becomes a signal that can be displayed on the display device 4. to generate an image signal S _T for display (step S105). The display image generation unit 35 outputs the generated image signal _ST to the display device 4. Display device 4 displays an image corresponding to the image signal S _T inputted.

After generation of the image signal S _T by the display image generating unit 35, the control unit 38, an instruction signal according to the dimming control to the effect of generating a dimming signal to determine whether it is entered (step S106). For example, the control unit 38 determines whether or not the input unit 36 has received an operation input of an instruction signal for generating a dimming signal. If the control unit 38 determines that an instruction signal for generating a dimming signal has not been input (step S106: No), the image signal processing is terminated.

  When the control unit 38 determines that an instruction signal for generating a dimming signal is input (step S106: Yes), the control unit 38 determines whether the brightness is based on an image (for example, an image after synthesis) based on the acquired imaging signal. The exposure amount is detected and the exposure amount is set, and the light emission amount (including the intensity and time) corresponding to the set exposure amount or the dimming signal indicating the shutter opening time is generated (step S107). The control unit 38 inputs the generated dimming signal to the endoscope 2 or the light source unit 3a, and ends the image signal processing.

According to the embodiment of the present invention described above, the dividing unit 32 acquires the input image signal S _C from the imaging signal acquisition unit 31, and the component other than the detail component signal S _D and the component signal of the detail component signal. is divided into a base component signal S _B containing signal, the brightness adjustment unit 33, the base component signal S performs brightness adjustment processing to the _B, the combining unit 34, the detail component signal dividing section 32 divides S _{Since D} and the base component signal S _B ′ subjected to the brightness adjustment processing by the brightness adjustment unit 33 are synthesized, while suppressing the deterioration of the contrast of the bright part as in the conventional γ correction, The brightness can be adjusted.

In the above-described embodiment, the imaging signal acquisition unit 31 has been described as generating the input image signal S _C including an image to which the RGB color components are added. However, the luminance (Y ) and the component may be one for generating an input image signal S _C with YCbCr color space including the color difference components, three components of hue (hue), saturation (saturation chroma), lightness (Value lightness brightness) The input image signal S _C having components divided into color and luminance may be generated using an HSV color space consisting of the above, an L ^* a ^* b ^* color space using a three-dimensional space, or the like.

Further, in the embodiment described above, the brightness adjusting unit 33, with reference to the graph of the relative input luminance value and a relative output intensity values as shown in FIG. 3, with respect to the input luminance value of the base component signal S _B Although described as adjusting the brightness of the luminance value below the threshold, the threshold for the input luminance value can be arbitrarily set, and a conventional γ correction process based on a γ curve may be applied.

Further, in the embodiment described above, the brightness adjusting unit 33, with reference to the graph of the relative input luminance value and a relative output intensity values as shown in FIG. 3, with respect to the input luminance value of the base component signal S _B Although it has been described that the brightness of the brightness value below the threshold is adjusted, the brightness may be adaptively adjusted according to the brightness value of the surrounding pixels. For example, a coefficient (gain coefficient) determined according to a luminance value (an average value, a mode value, etc.) of a predetermined pixel area may be multiplied by the luminance value of the pixel area. When the brightness adjustment is adaptively performed, the adjustment amount (gain map) changes for each obtained image, and the gain coefficient varies depending on the pixel position even with the same luminance value. As an index for such adaptive adjustment, for example, iCAM06: A refined image appearance model for HDR image rendering, Jiangtao Kuang, et al., J. Vis. Commun. Image R, 18 (2007) 406− A method using a white image described in 414 is known.

  In the above-described embodiment, the brightness adjustment unit 33 may change the brightness level according to the operation input received by the input unit 36, or emphasize the contrast component included in the detail component signal. You may make it perform the outline emphasis process to perform.

  In the above-described embodiment, the light source unit 3a has been described as being a simultaneous illumination / imaging method in which white light is emitted from the light source unit 3a and the light receiving unit 244a receives light of each color component of RGB. However, a surface-sequential illumination / imaging method in which light in the wavelength band of RGB color components is separately emitted sequentially and the light receiving unit 244a receives light of each color component, respectively.

  In the above-described embodiment, the light source unit 3a has been described as being configured separately from the endoscope 2. However, for example, a light source device such as a semiconductor light source is provided at the distal end of the endoscope 2. The structure provided in the endoscope 2 may be sufficient. Furthermore, the function of the processing device 3 may be given to the endoscope 2.

  Moreover, although the light source part 3a was demonstrated as what was integrated with the processing apparatus 3 in embodiment mentioned above, the light source part 3a and the processing apparatus 3 are separate bodies, for example, it illuminates the exterior of the processing apparatus 3. The part 301 and the illumination control part 302 may be provided.

  In the above-described embodiment, the image signal processing apparatus according to the present invention includes the dividing unit 32 of the endoscope system 1 using the flexible endoscope 2 whose observation target is a living tissue or the like in the subject. Although described as functioning as the brightness adjustment unit 33 and the synthesis unit 34, a rigid endoscope, an industrial endoscope for observing material characteristics, a capsule endoscope, a fiberscope, an optical view The present invention can also be applied to an endoscope system using a camera head connected to an eyepiece of an optical endoscope such as a tube. The image signal processing apparatus according to the present invention can be applied to both inside and outside the body, and performs division, brightness adjustment, and composition processing on a video signal including an imaging signal and an image signal generated outside. is there.

  In the above-described embodiment, the endoscope system has been described as an example. However, the present invention can also be applied to, for example, outputting an image to an EVF (Electronic View Finder) provided in a digital still camera or the like.

  As described above, the image signal processing method, the image signal processing apparatus, and the image signal processing program according to the present invention are useful for adjusting the brightness while suppressing the deterioration of the contrast.

DESCRIPTION OF SYMBOLS 1 Endoscope system 2 Endoscope 3 Processing apparatus 3a Light source part 4 Display apparatus 21 Insertion part 22 Operation part 23 Universal code 24 Tip part 25 Bending part 26 Flexible pipe part 31 Imaging signal acquisition part 32 Dividing part 33 Brightness adjustment Unit 34 composition unit 35 display image generation unit 36 input unit 37 storage unit 38 control unit 301 illumination unit 302 illumination control unit 371 brightness adjustment information storage unit

Claims (7)

A dividing step of dividing the video signal into a first signal including a contrast component signal and a second signal including a component signal other than the component signal included in the first signal among the component signals of the video signal;
A brightness adjustment step of performing a brightness adjustment process on the second signal among the component signals divided in the division step;
A synthesis step of synthesizing the first signal divided in the division step and the second signal after the brightness adjustment in the brightness adjustment step;
An image signal processing method comprising: The video signal includes a plurality of color components,
The image signal processing method according to claim 1, wherein the division step, the brightness adjustment step, and the synthesis step perform independent signal processing on each color component. In the brightness adjustment step, the brightness value of the second signal is increased with respect to the brightness value of the second signal by increasing the brightness value smaller than the threshold value and making the brightness value equal to or greater than the threshold value equal. The image signal processing method according to claim 1, wherein a depth adjustment process is performed. The image signal processing method according to claim 1, wherein the brightness adjustment step adaptively adjusts the brightness based on a luminance value of the second signal. A dimming signal generating step for generating a dimming signal based on the synthesized image signal synthesized by the synthesizing step,
The image signal processing method according to claim 1, further comprising: A dividing unit that divides the video signal into a first signal including a contrast component signal and a second signal including a component signal other than the component signal included in the first signal among the component signals of the video signal;
Among the component signals divided by the dividing unit, a brightness adjusting unit that performs a brightness adjusting process on the second signal;
A combining unit that combines the first signal divided by the dividing unit and the second signal after brightness adjustment by the brightness adjustment unit;
An image signal processing apparatus comprising: A division procedure for dividing the video signal into a first signal including a contrast component signal and a second signal including a component signal other than the component signal included in the first signal among the component signals of the video signal;
A brightness adjustment procedure for performing a brightness adjustment process on the second signal among the component signals divided in the division procedure;
A synthesis procedure for synthesizing the first signal divided by the division procedure and the second signal after the brightness adjustment by the brightness adjustment procedure;
An image signal processing program for causing a computer to execute the above.

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