Electronic endoscope system and signal processor

Abstract

Electronic endoscope system (10) with: - an RGB converter (21, 22) which converts image signals into RGB signals; - an R-signal amplifier (31R) which changes the amplitude of the R signals contained in the RGB signals to a predetermined gain value; and - a GB signal amplifier (31G, 31B) which non-linearly changes the amplitudes of the G and B signals contained in the RGB signals, characterized in that the gains of the G and B signals contained in the RGB signals are smaller than the gain of the R signals contained in the RGB signals, and in that the deviation between the gains of the G and B signals contained in the RGB signals and the gain of the R signals contained in the RGB signals is greater in the lower range of the R, G and B signals than in the upper range of the R, G and B signals.

Description

[0001] The invention relates to an electronic endoscope system and a signal processor for an electronic endoscope. In particular, the invention relates to signal processing in an electronic endoscope system.

[0002] An electronic endoscope system is known that uses narrowband illumination light to generate an image within a specific spectral band, highlighting features such as blood vessels, damaged areas, and the like. Such an endoscope system is described in JP 2006-061620 A. However, this prior art system requires a dedicated light source. This leads to increased system costs. Furthermore, this system is disadvantageous with regard to simultaneously viewing a normal endoscopic image under white light. In JP 2006-239206 A, a white-light spectral image is emulated by applying a matrix corresponding to the aforementioned narrowband to a color transformation matrix normally used in image processing.

[0003] However, the image processing described in JP 2006-239206 A is complicated. Furthermore, it is difficult to emulate a desired spectral image using a linear transformation. Features of an object under observation, such as damage, cannot be highlighted clearly enough. For example, in endoscopy, damage can be identified via a pattern of distributed blood vessels. However, the image processing described in JP 2006-239206 A cannot effectively distinguish the blood vessels from the surrounding tissue, so a comparison with an image exhibiting a normal spectrum is required for a suitable diagnosis.

[0004] Document DE 102 26 582 A1 discloses an electronic endoscope comprising a videoscope with an image sensor and a video processor to which the videoscope is detachably connected. The electronic endoscope comprises a light source that emits light to illuminate an object, a color adjustment means that performs a color adjustment process on the color image signals read from the image memory, which contain a plurality of color signal components corresponding to a plurality of color elements, and a light source detector that detects the light source type. The color adjustment means performs the color adjustment process according to the light source type so that the color is correctly reproduced in a displayed object image.

[0005] Document US 6,441,845 B1 discloses an endoscopic image pickup device comprising a camera head with an image pickup device, a videoscope to which the camera head is detachably connected, and a light source device that supplies illumination light to the videoscope. A camera control unit (CCU) is provided as a processor body that performs signal processing for the image pickup device provided in the camera head. A monitor displays a standard image signal processed by the CCU. A detection circuit in the CCU detects the luminance of an image from a digital RGB signal output from a color separation circuit, and a detection output of the detection circuit is output to a CPU. The CPU judges whether the luminance of an image is equal to or greater than a predetermined value and controls a peripheral interface (I / F) based on the luminance value of the image.The peripheral I / F outputs adjustment signals and control signals to an exposure control circuit and a CCD driver.

[0006] Document US 2006 / 0 211 915 A1 discloses an endoscope device comprising an endoscope having an imaging device that generates a color image signal of a body to be observed, a storage section that stores matrix data relating to a wavelength range in which a spectral image is formed, a spectral image generation circuit that performs matrix calculation based on the color image signals using the matrix data of the storage section and generates a spectral image of a selected wavelength range, and a wavelength selection section that selects the wavelength range of the spectral image generated by the spectral image generation circuit through a continuous state change or a stepwise state change.

[0007] Document EP 1 698 271 A1 discloses an endoscope device comprising an endoscope with an imaging device that forms a color image signal of a body to be observed, a storage section that stores matrix data for generating a spectral image based on the color image signal, a spectral image generating circuit that performs a matrix calculation based on the color image signal using the matrix data of the storage section and generates at least one spectral image signal, each of which corresponds to an arbitrarily selected wavelength range, and an amplifier circuit that amplifies the at least one spectral image signal generated by the spectral image generating circuit.

[0008] The object of the invention is to create a way of generating an image in an electronic endoscope system using white light illumination in which the blood vessels are sufficiently highlighted.

[0009] The invention solves this problem by the subject matter of the independent claims. Advantageous further developments are specified in the subclaims.

[0010] The invention, along with its advantages, is described below with reference to the figures, in which: Fig. 1 is a block diagram of an electronic endoscope system as an embodiment; Fig. 2 a block diagram of the Fig. 1 RGB gain control unit; Fig. 3 shows an example of a screen image displayed on a display device used to select the gain factor; and Fig. 4 a graph showing the gain (as a ratio) of the RGB output signal and the RGB input signal.

[0011] The invention is described below using an embodiment.

[0012] Fig. 1 is a block diagram schematically showing the general structure of an electronic endoscope system according to an embodiment.

[0013] As is known per se from the prior art, the electronic endoscope system 10 includes an observation part 11 with a flexible tube insertable into a body, a processing unit 12 to which the observation part 11 is detachably attached and which receives image signals from the observation part 11 in order to perform image processing thereon, and one or more output devices, e.g., a monitor 13 on which the images obtained from the processing unit 12 are displayed, and / or a printer 14 which records the images.

[0014] At the distal end of the flexible tube of the observation part 11 are a recording lens 15 and an imaging device 16. A timing signal generator 17, located, for example, within the observation part 11, controls the imaging device 16. The imaging device 16 captures images inside the body under white light, which is provided via a light guide 18 from a light source 19 arranged in the processing unit 12.

[0015] The analog image signals obtained from the imaging device 16, which are related to the RGB complementary colors, are converted into digital image signals in an analog input circuit 20 and then converted into RGB signals by a color interpolation circuit 21 and a matrix circuit 22. The RGB signals are then converted into YCrCb signals in an RGB / YCrCb converter 23 and fed to the processing unit 12. The YCrCb signals fed to the processing unit 12 are then subjected to contour compensation, for example, in a contour compensation circuit 24 and converted into RGB signals in a YCrCb / RGB converter 25. The RGB signals originating from the YCrCb / RGB converter 25 are amplified by an RGB gain controller 26 to predetermined gains (gain ratios) and then fed to a scale controller 27.The RGB signals amplified by the RGB gain controller 26 are subjected to size compensation based on the image size and output to the monitor 13 or the printer 14.

[0016] The RGB gain controller 26 is connected to a CPU 28. The CPU 28 controls the RGB gain controller 26 according to commands input via a button provided on a control panel 29. Furthermore, a display device 30, such as an LCD monitor, is connected to the CPU 28.

[0017] With reference to the Fig. 2 and Fig. 3, the structure and function of the RGB gain control 26 according to the embodiment are explained below. Fig. 2 is a block diagram schematically showing the structure of the RGB gain controller 26. Fig. 3 shows an example of an operating menu, namely a screen display for selecting gain settings, which is displayed on the display device 30 in order to adjust the RGB gain control 26.

[0018] The RGB gain controller 26 includes an R-signal amplifier 31R, a G-signal amplifier 31G, and a B-signal amplifier 31B, to which an R-signal RIN, a G-signal GIN, and a B-signal BIN are supplied from the YCrCb / RGB converter 25, respectively. The R-signal amplifier 31R, the G-signal amplifier 31G, and the B-signal amplifier 31B each comprise a plurality of amplifiers. Fig. For simplicity, Figure 2 shows three amplifiers GR1-GR3 for the R-signal amplifier 31R, three amplifiers GG1-GG3 for the G-signal amplifier 31G, and three amplifiers GB1-GB3 for the B-signal amplifier 31B. If an operating mode in which the gain control for highlighting the blood vessels is bypassed is selected by operating the control panel 29, the amplifiers 31R, 31G, and 31B of the RGB gain control 26 output RGB signals proportional to the input signals with the same gain.

[0019] In the present embodiment, the gain control for highlighting the blood vessels in a target organ is performed on each of the R, G, and B signals. As shown in Fig. 3, the screen S of the display device 30 lists the names of the target organs (e.g., "Organ 1", "Organ 2", ..., "Organ 6"; boxes P1-P6). Each of the boxes P1-P6, each assigned to a target organ, can be selected by the operator by operating the control panel 29. Examples of the target organs are the stomach, the intestine, the esophagus, and the lungs.

[0020] In the R-signal amplifier 31R, the G-signal amplifier 31G, and the B-signal amplifier 31B, the RGB gain levels are individually controlled so that the blood vessels on the selected target organ to be viewed are clearly highlighted. In the illustration according to Fig. 2, amplifiers GR1, GG1, and GB1 each amplify the input signals RIN, GIN, and BIN with a gain appropriate for target organ 1, and in turn output the RGB signals R1, G1, and B1. Similarly, amplifiers GR2, GG2, and GB2 amplify the input signals RIN, GIN, and BIN with gain appropriate for target organ 2, and output the RGB signals R2, G2, and B2. Similarly, amplifiers GR3, GG3, and GB3 amplify the input signals RIN, GIN, and BIN with gain appropriate for target organ 3, and output the RGB signals R3, G3, and B3.

[0021] The R signals R1-R3 output from the R signal amplifier 31R are supplied to a selector 32R, the G signals G1-G3 output from the G signal amplifier 31G are supplied to a selector 32G, and the B signals B1-B3 output from the B signal amplifier 31B are supplied to a selector 32B.

[0022] The selectors 32R-32B are controlled by selection signals SELR, SELG, and SELB, respectively. Thus, the selectors 32R-32B select a set of RGB signals that correspond to the image displayed on the screen. Fig. 3 is selected, and output the RGB output signals ROUT, GOUT, and BOUT. For example, if organ 1 is selected, the signals R1, G1, and B1 are selected by selectors 32R, 32G, and 32B and output as signals ROUT, GOUT, and BOUT. The ROUT, GOUT, and BOUT signals are output to scale controller 27.

[0023] In the following, with reference to Fig. 4, the gain levels adjusted by the R-signal amplifier 31R, the G-signal amplifier 31G, and the B-signal amplifier 31B are explained in detail.

[0024] Fig. 4 is a graph showing the relationship between the input signals RIN, GIN and BIN and the output signals Rn, Gn and Bn (n=1, 2, 3 for the example of Fig. 2) output by the R-signal amplifier 31R, the G-signal amplifier 31G, and the B-signal amplifier 31B. The abscissa indicates the values ​​of the input signals, and the ordinate indicates the values ​​of the output signals. In the present embodiment, the amplification levels are controlled so that the blood vessels in the selected observation target, i.e., the organ, are emphasized. For this emphasis, the output gain of the R-signal for all targets is set proportional to the input gain, as shown in Fig. 4. Thus, the gain of the R signal is constant over the entire dynamic range, as shown in Fig. 4 is indicated by the straight line L. However, the gains are set individually for each observation target, so different gain values ​​can be set for different observation targets. Regarding the G signals and the B signals, the gain values ​​vary in the dynamic range according to the Fig. 4. In the lower range of the input signals, the gains for the G signal and the B signal are set to comparatively small values ​​compared to the gain value for the R signal. The gains of the G signal and the B signal gradually increase with increasing input signal value and reach a value equal to the gain of the R signal at the maximum value of the dynamic range. In the example according to Fig. In Figure 4, the gains for the G signal and the B signal are represented by the same curve C. However, they can also be set to different curves.

[0025] The gain G(x) for each input signal x (y=G(x)*x, where y represents the output signal) is preset in a memory device provided as a look-up table in each of the memories 31R, 31G, and 31B. In each of these amplifiers, the gains are controlled by referring to the gain values ​​stored in the memory devices.

[0026] In the present embodiment, the nonlinear conversion of the RGB signals is performed after the RGB conversion performed in the processing unit. However, the nonlinear conversion can also be performed at any other suitable time between the analog input process and the image display. In the present embodiment, the observation target, i.e., the organ, is selected on the screen of the display device provided on the processing unit. However, this selection can also be made on a screen of a computer system or the monitor used in the endoscope system.

[0027] As described above, in the present embodiment, an endoscopic image in which the blood vessels are emphasized is generated by a simple structure by appropriately adjusting the gains of the RGB signals, for example, by adjusting the gain for the R signal linearly while adjusting the gains for the G and B signals nonlinearly. Furthermore, since the luminance and hue remain virtually unchanged throughout the image by the blood vessel emphasis or the spectral image emulation according to the present invention, it is not strange for the operator to compare the image in which the blood vessels are emphasized, that is, the emulated spectral image, with the normal endoscopic image (without nonlinear gain control).

Claims

[1] Electronic endoscope system (10) with: - an RGB converter (21, 22) which converts image signals into RGB signals; - an R-signal amplifier (31R) which changes the amplitude of the R signals contained in the RGB signals to a predetermined gain value; and - a GB signal amplifier (31G, 31B) which non-linearly changes the amplitudes of the G and B signals contained in the RGB signals, characterized by that the gains of the G and B signals contained in the RGB signals are smaller than the gains of the R signals contained in the RGB signals, and that the deviation between the gains of the G and B signals contained in the RGB signals and the gain of the R signals contained in the RGB signals is larger in the lower range of the R, G and B signals than in the upper range of the R, G and B signals. [2] The electronic endoscope system (10) according to claim 1, wherein the gains of the R signal amplifier (31R) and the GB signal amplifier (31G, 31B) are recorded in the form of values ​​specifically designed for different observation targets, and the gains are selectable depending on the selected observation target. [3] The electronic endoscope system (10) according to claim 2, further comprising a selector (P1 - P6) for selecting the observation target. [4] Signal processor for an electronic endoscope, comprising: - an RGB converter (21, 22) which converts image signals into RGB signals; - an R-signal amplifier (31R) which changes the amplitude of the R signals contained in the RGB signals to a predetermined gain value; and - a GB signal amplifier (31G, 31B) which non-linearly changes the amplitudes of the G and B signals contained in the RGB signals, characterized bythat the gains of the G and B signals contained in the RGB signals are smaller than the gains of the R signals contained in the RGB signals, and that the deviation between the gains of the G and B signals contained in the RGB signals and the gain of the R signals contained in the RGB signals is larger in the lower range of the R, G and B signals than in the upper range of the R, G and B signals.

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