JP4832411B2 - Noise reduction processing apparatus and noise reduction processing method - Google Patents

Description

  The present invention relates to a noise reduction processing device and a noise reduction processing method for reducing noise included in a video signal.

  As a technique for performing noise reduction processing on a video signal such as a television signal, there is a technique using both three-dimensional noise reduction and one-dimensional / two-dimensional noise reduction processing on image data obtained by digitizing the video signal. is there.

  Here, the one-dimensional noise reduction processing is generally performed using the correlation between adjacent pixels in the same line. In addition, the two-dimensional noise reduction processing is generally performed using the correlation between adjacent lines. In addition, the three-dimensional noise reduction processing is generally performed using a correlation between two successive frames.

  Here, in one-dimensional noise reduction processing or two-dimensional noise reduction processing (hereinafter also referred to as one-dimensional / two-dimensional noise reduction processing), data of adjacent pixels in the same frame is used. For this reason, when there is no identity between the data of adjacent pixels, the image quality may be deteriorated by the one-dimensional / two-dimensional noise reduction processing.

  The three-dimensional noise reduction process provides an excellent noise reduction effect when the video is still, that is, when there is an identity between the current frame image and the previous frame image one frame before. It is done. However, if the video is moving, that is, if the identity between the current frame image and the previous frame image is lost, the image quality may be reduced by 3D noise reduction processing. May deteriorate.

  A method of synthesizing and optimizing the results of the three-dimensional noise reduction processing and the one-dimensional / two-dimensional noise reduction processing in order to solve the image quality degradation problem caused by the one-dimensional / two-dimensional noise reduction processing and the three-dimensional noise reduction processing. Has been proposed (see, for example, Patent Document 1 or 2).

  The techniques disclosed in Patent Documents 1 and 2 will be described with reference to FIGS. 8 and 9 are schematic configuration diagrams of a conventional noise reduction processing apparatus. FIG. 8 shows the configuration of Patent Document 1, and FIG. 9 shows the configuration of Patent Document 2. As shown in FIG.

  First, the noise reduction device 110 disclosed in Patent Document 1 will be described with reference to FIG.

  In the noise reduction device 110 disclosed in Patent Document 1, an input video signal is digitally converted and then converted into image data as a three-dimensional noise reduction processing unit 120, a one-dimensional / two-dimensional noise reduction processing unit 150, and a motion. It is sent to the determination unit 130 in parallel. The motion determination unit 130 detects the motion by comparing the image data of the current frame with the image data of a plurality of frames before the current frame stored in the plurality of frame memories 140, 142, and 144, respectively. The first synthesis processing unit 170 synthesizes image data of a plurality of frames at a ratio according to the motion information detected by the motion determination unit 130, and the obtained synthesized frame image data is converted into a three-dimensional noise reduction processing unit. Send to 120.

  The three-dimensional noise reduction processing unit 120 performs three-dimensional noise reduction processing on the image data of the current frame using the composite frame image data, and sends the result to the second synthesis processing unit 162. The one-dimensional / two-dimensional noise reduction processing unit 150 performs one-dimensional / two-dimensional noise reduction processing on the image data of the current frame, and sends the result to the second synthesis processing unit 162. The second synthesis processing unit 162 synthesizes the result of the three-dimensional noise reduction processing and the result of the one-dimensional / two-dimensional noise reduction at a ratio according to the motion information detected by the motion determination unit 130, and the synthesis. Output the result. At this time, the second synthesis processing unit 162 sends the synthesis result to the frame memory 140.

  Next, the noise reduction device 112 disclosed in Patent Document 2 will be described with reference to FIG.

  In the noise reduction device 112 disclosed in Patent Document 2, the input video signal is digitally converted and then stored in the frame memory 140 as image data of the previous frame one frame before the current frame. After being synchronized with the image data, it is sent in parallel to the two-dimensional noise reduction processing unit 152, the three-dimensional noise reduction processing unit 120 and the motion determination unit 130. The three-dimensional noise reduction processing unit 120 uses the image data of the previous frame with the degree of noise reduction determined by the frame cyclic coefficient determination unit 172 according to the degree of motion detected by the motion determination unit 130. 3D noise reduction processing is performed on the image data.

The output of the two-dimensional noise reduction processing unit 152 and one of the outputs of the three-dimensional noise reduction processing unit 120 are combined by the signal combining unit 162 at the combining ratio determined by the combining ratio determining unit 174 and then output. This combination ratio is determined according to the degree of motion detected by the motion determination unit 130. The other output of the three-dimensional noise reduction processing unit 120 is sent to the frame memory 140 and stored therein.
JP 2006-287632 A JP 2005-150903 A

  However, in the technique disclosed in Patent Document 1 described above, image data obtained by synthesizing the result of the three-dimensional noise reduction process and the result of the one-dimensional / two-dimensional noise reduction process is sent to the frame memory. That is, a video signal whose image quality is deteriorated by the one-dimensional / two-dimensional noise reduction processing is used for motion detection or three-dimensional noise reduction. This leads to a decrease in motion detection accuracy or a deterioration in image quality during the three-dimensional noise reduction process.

  In the technique disclosed in Patent Document 2, the result of the 1D / 2D noise reduction process is not sent to the frame storage unit, but the 3D noise reduction process and the 1D / 2D noise reduction process are performed in parallel. Therefore, there are cases where the effect of noise reduction is not sufficient.

  For example, when the effect of reducing the three-dimensional noise is 0 to −6 dB and the effect of reducing the one-dimensional / two-dimensional noise is −3 dB, the effect of reducing the noise in the synthesized signal is 0 to 1 in a. (0 to −6 dB) × a + (− 3 dB) × (1−a).

  Therefore, when the inventor according to this application has intensively studied, the effect of noise reduction is achieved by performing the three-dimensional noise reduction processing and the one-dimensional / two-dimensional processing in this order in series in a moving part. It was found to be (0 to −6 dB) + (− 3 dB).

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to effectively remove noise particularly in a portion where there is a motion without causing a deterioration in image quality when reducing three-dimensional noise. Accordingly, it is an object of the present invention to provide a noise reduction processing device and a noise reduction processing method for obtaining an image with good image quality.

  In order to achieve the above-described object, according to the first aspect of the present invention, a three-dimensional noise reduction processing unit, a one-dimensional / two-dimensional noise reduction processing unit, a motion determination unit, a storage unit, and noise reduction are provided. A noise reduction processing apparatus including a signal generation unit is provided.

  The three-dimensional noise reduction processing unit receives image data, adjusts the three-dimensional noise reduction on the image data, and outputs it as a three-dimensional noise reduction signal. The storage unit stores one frame of the three-dimensional noise reduction signal. The motion determination unit determines the motion of the image data between the same pixels in the preceding and succeeding frames and outputs a motion determination signal. The one-dimensional / two-dimensional noise reduction processing unit performs one or both of the one-dimensional noise reduction processing and the two-dimensional noise reduction processing on the three-dimensional noise reduction signal and outputs the result as a one-dimensional / two-dimensional noise reduction signal. . The noise reduction signal generation unit generates a noise reduction signal including the three-dimensional noise reduction signal and the one-dimensional / two-dimensional noise reduction signal at a ratio according to the result of determination of the presence / absence of motion in the motion determination unit.

When the image data of the current frame is input to the 3D noise reduction processing unit and the motion determination unit, the image data of the immediately previous frame immediately before the current frame is sent from the storage unit to the 3D noise reduction processing unit and the motion determination unit. The motion determination unit compares the difference of the image data between the same pixels in the current frame and the immediately preceding frame with a threshold value under a plurality of conditions, and determines the state with and without motion and the transition state between them. A multi-bit motion determination signal is generated, and the motion determination signal is output as a motion determination signal of the current frame to the three-dimensional noise reduction processing unit and the noise reduction signal generation unit, and the three-dimensional noise reduction processing unit depending on the result of the motion determination signal, it performs three-dimensional noise reducing process between the same pixel of the current frame and the previous frame, and outputs the three-dimensional noise reducing signal, the motion determination No. Depending on the magnitude of the value indicated by the sets the intensity of the degree of noise reduction.

  According to the second aspect of the present invention, there is provided a noise reduction processing method having the following processes.

  First, image data of the current frame to be subjected to noise reduction processing is input. Next, it is determined whether or not there is motion of image data between the same pixels for the current frame and the frame immediately before the current frame. Next, a three-dimensional noise reduction signal is generated by performing a three-dimensional noise reduction process between the same pixels of the current frame and the immediately preceding frame according to the result of the determination of the presence or absence of motion.

Next, the three-dimensional noise reduction signal is newly stored in the storage unit as image data of the immediately preceding frame. Next, one or both of the one-dimensional noise reduction process and the two-dimensional noise reduction process are performed on the three-dimensional noise reduction signal to generate a one-dimensional / two-dimensional noise reduction signal. Next, a noise reduction signal including a three-dimensional noise reduction signal and a one-dimensional / two-dimensional noise reduction signal is generated at a ratio corresponding to the result of the presence / absence determination of the motion indicated by the motion determination signal.
When determining the presence or absence of movement, the difference between the image data between the same pixels in the current frame and the previous frame is compared with a threshold value under a plurality of conditions. When generating a multi-bit motion determination signal indicating a transition state and generating a three-dimensional noise reduction signal, the degree of noise reduction is set according to the magnitude of the value indicated by the motion determination signal .

  According to the noise reduction processing device and the noise reduction processing method of the present invention, the frame information stored in the storage unit is obtained by performing only the three-dimensional noise reduction processing, and there is a possibility that the image quality may be deteriorated. What has been subjected to the two-dimensional noise reduction processing is not stored. For this reason, it is possible to suppress a decrease in accuracy of motion detection due to a deterioration in image quality and a deterioration in image quality during the three-dimensional noise reduction process.

  Also, the 1D / 2D noise reduction process is performed on the signal that has been subjected to the 3D noise reduction process, that is, the 3D noise reduction process and the 1D / 2D noise reduction process are performed in this order in series. When there is movement, the noise reduction effect can be enhanced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments are merely schematically shown to the extent that the present invention can be understood. Moreover, numerical conditions etc. are only suitable examples. Therefore, the present invention is not limited to the following embodiments, and many changes or modifications that can achieve the effects of the present invention can be made without departing from the scope of the configuration of the present invention.

(Noise reduction processing apparatus of the first embodiment)
With reference to FIG. 1, the noise reduction processing apparatus of 1st Embodiment is demonstrated. FIG. 1 is a schematic configuration diagram for explaining a noise reduction processing apparatus according to the first embodiment.

  The noise reduction processing device 10 includes a three-dimensional noise reduction processing unit 20, a one-dimensional / two-dimensional noise reduction processing unit 50, a motion determination unit 30, a storage unit 40, and a noise reduction signal generation unit 60. Is done.

  The noise reduction processing device 10 performs noise reduction processing in response to input of image data obtained by digitally converting a video signal, and outputs the result of the noise reduction processing as a noise reduction processing signal. The noise reduction processing apparatus 10 can be configured as an integrated circuit (LSI) including the above-described components, for example.

  Here, the video signal is used for a television signal, for example, and includes at least one of a luminance signal (Y signal) representing brightness and a color difference signal (C signal) representing chromaticity. . Here, the chromaticity is a combination of hues such as red, green, and blue, and saturation indicating color depth and vividness.

  The video signal has image information of a frame corresponding to one screen in units of pixels. The video signal is digitized and input to the noise reduction processing apparatus, so that the noise reduction processing apparatus sequentially receives image data for each frame. This image data includes, for example, luminance information and chromaticity information. As is clear from the above description, the image information of the frame is a video signal in the analog display and is image data in the digital display.

  Image data (indicated by an arrow 11 in the figure, hereinafter referred to as input image data) input to the noise reduction processing apparatus 10 is divided into two in the noise reduction processing apparatus 10. One of the two parts (indicated by an arrow 13 in the figure) is sent to the three-dimensional noise reduction processing unit 20, and the other (indicated by an arrow 15 in the figure) is sent to the motion determining unit 30. Further, image data output from the storage unit 40 (indicated by an arrow 41 in the figure, hereinafter also referred to as stored image data) is divided into two and divided into two (indicated by an arrow 43 in the figure). .) Is sent to the three-dimensional noise reduction processing unit 20, and the other (indicated by an arrow 45 in the figure) is sent to the motion determination unit 30.

  As the storage unit 40, any suitable conventionally known one such as a so-called frame memory can be used. The storage unit (frame memory) 40 receives the three-dimensional noise reduction signal generated by the three-dimensional noise reduction processing unit 20. The storage unit 40 stores a three-dimensional noise reduction signal for one frame.

  Although the function of the three-dimensional noise reduction processing unit 20 will be described later, the three-dimensional noise reduction signal (indicated by an arrow 21 in the figure) generated by the three-dimensional noise reduction processing unit 20 is branched into three (arrow 23 in the figure). , 25 and 27.), in addition to the storage unit 40, it is also sent to the one-dimensional / two-dimensional noise reduction processing unit 50 and the noise reduction signal generation unit 60.

  The storage unit 40 outputs the stored image data for one frame as stored image data 41. Here, the stored image data 43 and 45 input to the three-dimensional noise reduction processing unit 20 and the motion determination unit 30 are one frame of the frames belonging to the input image data 11, 13 and 15 (hereinafter referred to as the current frame). Image data of the previous frame (hereinafter referred to as the immediately preceding frame) is shown. In other words, the storage unit 40 delays the three-dimensional noise reduction processing signal by one frame and sends it to the three-dimensional noise reduction processing unit 20 and the motion determination unit 30. As a result, when the image data of the current frame is input to the three-dimensional noise reduction processing unit 20 and the motion determination unit 30, the image data of the immediately preceding frame is synchronized with the input of the image data of the current frame. 20 and the motion determination unit 30.

  The motion determination unit 30 determines the presence / absence of image data motion between the same pixels in the preceding and following frames, and outputs the result as a motion determination signal. Here, the motion determination of the current frame is performed based on the image data of the current frame indicated by the input image data 15 and the image data of the immediately preceding frame indicated by the stored image data 45. The motion determination unit 30 can have any suitable conventionally known configuration having a function of performing motion detection, that is, determining the presence or absence of motion, such as the motion detection unit of Patent Documents 1 and 2.

  The determination of the presence or absence of motion in the motion determination unit 30 is performed, for example, by taking the difference in image data between the same pixels in the current frame and the immediately preceding frame. If there is no difference between the image data in the same pixel for the current frame and the previous frame, it is determined that there is no motion. On the other hand, if there is a difference in image data in the same pixel, it is determined that there is a motion.

  Hereinafter, a specific example of this determination will be described in more detail. The motion determination unit 30 calculates a difference value between image data of one pixel (may be referred to as a target pixel) that is a target of determination of presence or absence of motion in the current frame and a corresponding target pixel in the immediately preceding frame. . The difference value is calculated, for example, for luminance information or chromaticity information digitized to 8 bits. Hereinafter, the digitized luminance information or chromaticity information for each pixel will be described as a pixel value.

  The obtained difference value is compared with a predetermined threshold value (motion determination threshold value), and if the difference value is larger than the motion determination threshold value Vth, it is determined that the target pixel has movement. On the other hand, if the difference value is equal to or less than the motion determination threshold value Vth, it is determined that there is no motion in the target pixel. The motion determination unit 30 generates and outputs a motion determination signal (indicated by an arrow 31 in the figure) indicating the result of the motion determination. In this way, the motion determination signal obtained by determining the presence or absence of motion between the current frame and the immediately preceding frame is output as the motion determination signal of the current frame.

  The motion determination signal 31 is, for example, a 1-bit digital signal. When it is determined that there is no motion, the motion determination signal 31 is at a low (L) level indicating “0”, and when it is determined that there is motion, “1”. It becomes a high (H) level signal indicating. The motion determination signal 31 is branched into two, one (indicated by an arrow 33 in the figure) is sent to the three-dimensional noise reduction processing unit 20, and the other (indicated by an arrow 35 in the figure) is a noise reduction signal. It is sent to the generation unit 60.

  The motion determination threshold value Vth may be provided as an electrical signal from the outside of the motion determination unit 30 or may be set in advance according to an electrical resistance value inside the motion determination unit 30 or the like. It is also good.

  The three-dimensional noise reduction processing unit 20 can have any suitable conventionally known configuration that has a function of performing three-dimensional noise reduction processing on input image data and outputting it as a three-dimensional noise reduction signal. .

  The three-dimensional noise reduction process is performed between the same pixels of the current frame and the immediately preceding frame according to the result of the presence / absence determination of the motion indicated by the motion determination signal of the current frame. The pixel value of the current frame after the three-dimensional noise reduction is obtained by, for example, the following calculation formula (1).

Pixel value after three-dimensional noise removal = pixel value of current frame (before three-dimensional noise removal) − (pixel value of current frame−pixel value of corresponding pixel of immediately preceding frame) × α (1)
Here, α is a coefficient indicating the degree of noise reduction, and satisfies 0 ≦ α <1. As α is smaller, the degree of noise reduction is smaller, and as α is larger, the degree of noise reduction is larger.

  The three-dimensional noise reduction processing unit 20 receives the motion determination signal 33 generated by the motion determination unit 30, and according to the result of the motion determination indicated by the motion determination signal, the degree of noise reduction in the three-dimensional noise reduction processing, that is, the coefficient α Adjust. In this case, the three-dimensional noise reduction process is a process of combining the image data of the current frame and the image data of the immediately preceding frame at a ratio determined by the coefficient α.

  For example, if it is determined that there is movement as a result of the determination of the presence or absence of motion, the degree of noise reduction is reduced, while if it is determined that there is no movement, the degree of noise reduction is increased. For example, when 0 ≦ α1 <α2 <1, if it is determined that there is motion, the coefficient α may be α1, and if it is determined that there is no motion, the coefficient α may be α2. .

  Note that the three-dimensional noise reduction processing unit 20 may set α1 = 0 when it is determined that there is a motion.

  By configuring in this way, the three-dimensional noise reduction processing unit 20 exhibits an excellent noise reduction effect by the noise reduction processing with the increased degree when there is no movement between the current frame and the immediately preceding frame. On the other hand, when there is a motion, the three-dimensional noise reduction processing unit 20 can prevent image quality degradation such as tailing in the video by reducing the degree of noise reduction processing.

  The three-dimensional noise reduction processing unit 20 generates and outputs a three-dimensional noise reduction signal 21 indicating the result of the three-dimensional noise reduction processing.

  The one-dimensional / two-dimensional noise reduction processing unit 50 performs one or both of the one-dimensional noise reduction processing and the two-dimensional noise reduction processing on the three-dimensional noise reduction signal 25 to obtain a one-dimensional / two-dimensional noise reduction signal ( In the figure, it is generated by the arrow 51) and output. The one-dimensional / two-dimensional noise reduction signal 51 is sent to the noise reduction signal generation unit 60.

  Here, the one-dimensional noise reduction processing is performed using the correlation between adjacent pixels (horizontal direction) in the same line of the current frame. The two-dimensional noise reduction process is performed using the correlation between adjacent lines (vertical direction) of the current frame. The one-dimensional noise reduction process and the two-dimensional noise reduction process may be performed using a conventionally known method. For example, the one-dimensional noise reduction process and the two-dimensional noise reduction process can be performed by a spatial filter process using a low-pass filter or a high-pass filter using adjacent data.

  Here, the 1D / 2D noise reduction signal is simply described as a 1D / 2D noise reduction signal. However, the 1D / 2D noise reduction signal is obtained by performing 3D noise reduction processing and 1D / 2D noise reduction processing on input image data. This is done in series in this order.

  The noise reduction signal generation unit 60 receives the motion determination signal 35 generated by the motion determination unit 30, and at a ratio according to the determination result of the presence or absence of motion indicated by the motion determination signal 35, the noise reduction signal 1 and 1 A noise reduction signal including a two-dimensional / two-dimensional noise reduction signal is generated.

  In the noise reduction processing apparatus 10 of the first embodiment, the noise reduction signal generation unit 60 sets the ratio of the one-dimensional / two-dimensional noise reduction signal to 1 when the motion determination unit 30 determines that there is motion, and The ratio of the three-dimensional noise reduction signal is set to zero. That is, the noise reduction signal generation unit 60 selects the one-dimensional / two-dimensional noise reduction signal as a noise reduction signal, and uses the noise reduction signal as an output signal (indicated by an arrow 61 in the figure). Output from.

  On the other hand, when it is determined that there is no movement, the ratio of the three-dimensional noise reduction signal is set to 1, and the ratio of the one-dimensional / 2-dimensional noise reduction signal is set to zero. That is, the noise reduction signal generation unit 60 selects the three-dimensional noise reduction signal as the noise reduction signal, and causes the noise reduction processing device 10 to output the noise reduction signal as the output signal 61.

  As described above, the noise reduction signal generation unit 60 selects and outputs one of the one-dimensional / two-dimensional noise reduction signal and the three-dimensional noise reduction signal. Therefore, the noise reduction signal generation unit 60 can be configured to have a signal switching function such as a selector.

(Noise reduction processing method of the first embodiment)
A noise reduction processing method according to the first embodiment will be described with reference to FIGS. FIG. 2 is a diagram illustrating a processing flow for explaining the noise reduction processing method according to the first embodiment. FIG. 3 is a timing chart schematically showing each signal in the noise reduction processing method of the first embodiment. 3A to 3E, the horizontal axis indicates the time axis. 3 (A) and 3 (B), the vertical axis represents the signal intensity in arbitrary units.

  Note that the noise reduction processing method of the first embodiment can be implemented using the noise reduction processing device described with reference to FIG. 1, and therefore, here, the noise reduction processing method will also be described with reference to FIG. To do.

  First, in step (hereinafter, step is indicated by S) 10, image data (input image data) of the current frame is input to the noise reduction processing apparatus. In S <b> 10, input image data 11 is input to the noise reduction processing device 10. The input image data 11 has image data of a frame corresponding to one screen in units of pixels, and the noise reduction processing device 10 sequentially receives image data for each frame. Here, the image data of the current frame is image data of one frame among frames sequentially received by the noise reduction processing apparatus 10 and indicates image data of a frame subjected to noise reduction processing.

  Next, in S20, the presence / absence of motion is determined using the image data of the current frame and the image data of the previous frame. Here, the image data of the immediately preceding frame is data one frame before the current frame, and is stored in the storage unit (frame memory) 40. The frame image data stored in the storage unit 40 is image data obtained as a result of a three-dimensional noise reduction process described later.

  In the determination process of the presence / absence of motion, first, the motion determination unit 30 calculates the difference ΔV of the image data between the same pixels of the current frame and the previous frame for each pixel. Here, the same pixel means a pixel in which the two-dimensional coordinates in the horizontal direction and the vertical direction of one frame are the same as the two-dimensional coordinates of another frame.

  The difference ΔV is compared with a predetermined motion determination threshold value Vth. If the difference ΔV is larger than the motion determination threshold value Vth, it is determined that the pixel has a motion. On the other hand, if the difference ΔV is equal to or less than the motion determination threshold value Vth, it is determined that there is no motion in the pixel (FIG. 3A). The motion determination unit 30 generates and outputs a motion determination signal 31 indicating the result of the motion determination. The motion determination signal 31 is, for example, a 1-bit digital signal. When it is determined that there is no motion, the motion determination signal 31 is at a low (L) level indicating “0”, and when it is determined that there is motion, “1”. Is a high (H) level signal (FIG. 3B).

  Next, in S30, a three-dimensional noise reduction signal 21 is generated by performing a three-dimensional noise reduction process between the same pixels of the current frame and the immediately preceding frame. The three-dimensional noise reduction processing is performed by the three-dimensional noise reduction processing unit 20.

  In this three-dimensional noise reduction process, the degree of three-dimensional noise reduction is adjusted according to the result of the presence / absence determination of motion indicated by the motion determination signal 33. When it is determined that there is movement, the degree of noise reduction is weakened. On the other hand, when it is determined that there is no movement, the degree of noise reduction is increased.

  The pixel value after the three-dimensional noise reduction processing is calculated using, for example, the above calculation formula (1). When 0 ≦ α1 <α2 <1, when it is determined that there is motion, the coefficient α may be α1, and when it is determined that there is no motion, the coefficient α may be α2.

  If it is determined that there is a motion as a result of the motion determination, α1 = 0 may be set.

  As a result of this three-dimensional noise reduction processing, the three-dimensional noise reduction signal 21 that is the output of the three-dimensional noise reduction processing unit 20 becomes a signal with a weak degree of three-dimensional noise removal when there is movement, and when there is no movement. The signal has a strong degree of three-dimensional noise removal (FIG. 3C).

  Next, in S40, the three-dimensional noise reduction signal 21 (23) generated by the three-dimensional noise reduction processing unit 20 is sent to the storage unit 40, and is stored in the storage unit 40 as image data of the immediately preceding frame.

  Next, in S50, the one-dimensional / two-dimensional noise reduction signal 51 is generated by performing one-dimensional / two-dimensional noise reduction processing on the three-dimensional noise reduction signal 25. Here, the 1D / 2D noise reduction processing is performed by the 1D / 2D noise reduction processing unit 50. The one-dimensional / two-dimensional noise reduction processing means one or both of one-dimensional noise reduction processing and two-dimensional noise reduction processing.

  The one-dimensional / two-dimensional noise reduction signal 51 is obtained by further subjecting the three-dimensional noise reduction signal 25 to a one-dimensional / two-dimensional noise reduction process. Accordingly, the one-dimensional / two-dimensional noise reduction signal 51 is obtained by performing one-dimensional / two-dimensional noise reduction on a signal having a weak degree of three-dimensional noise reduction when there is a motion. On the other hand, when there is no movement, a signal with a strong degree of three-dimensional noise reduction is obtained by reducing one-dimensional / two-dimensional noise (FIG. 3D).

  Next, in S <b> 60, the noise reduction signal generation unit 60 determines the presence / absence of motion from the result of motion determination indicated by the motion determination signal 35. Thereafter, in S70 or S75, the noise reduction signal generation unit 60 performs the three-dimensional noise reduction signal 27 and the one-dimensional / two-dimensional noise reduction signal 51 at a ratio corresponding to the result of the presence / absence determination of the motion indicated by the motion determination signal 35. Is generated and output.

  As a result of the determination of the presence or absence of motion in S60, if there is motion (yes), the ratio of the 1D / 2D noise reduction signal is set to 1 and the ratio of the 3D noise reduction signal is set to 0 in S70. That is, the noise reduction signal generation unit 60 selects and outputs the one-dimensional / two-dimensional noise reduction signal as the noise reduction signal. Here, the one-dimensional / two-dimensional noise reduction signal 51 is obtained by further performing one-dimensional / two-dimensional noise reduction processing on the three-dimensional noise reduction signal 25. Therefore, when there is a motion, the one-dimensional / two-dimensional noise reduction is performed on a signal whose degree of three-dimensional noise reduction is weak.

  On the other hand, if there is no motion as a result of the determination of the presence or absence of motion in S60 (no), the ratio of the three-dimensional noise reduction signal 25 is set to 1 and the ratio of the one-dimensional / two-dimensional noise reduction signal 51 is set to 0 in S75. To do. That is, the noise reduction signal generation unit 60 selects and outputs the three-dimensional noise reduction signal 25 as a noise reduction signal.

  The noise reduction signal generated in the process of S70 or S75 is output as the output signal 61 (FIG. 3E).

  The above processing is sequentially performed for all the pixels in the current frame. If the processing for all the pixels in the current frame has not been completed (No in S80), the processing is continued for the other pixels in the current frame. On the other hand, when the processing for all the pixels in the current frame is completed (Yes in S80), the processing in the current frame is terminated, and then the same processing is performed for the next frame immediately after the current frame. Done.

  According to the noise reduction processing apparatus and the noise reduction processing method of the first embodiment, the frame information stored in the storage unit is obtained by performing only the three-dimensional noise reduction processing, and the one-dimensional / two-dimensional noise reduction processing. I did not remember what I did. For this reason, image data whose image quality is deteriorated by the one-dimensional / two-dimensional noise reduction processing is not stored. Accordingly, it is possible to suppress the accuracy of motion detection and image quality degradation in the three-dimensional noise reduction processing.

  Further, since the one-dimensional / two-dimensional noise reduction processing is performed on the signal that has been subjected to the three-dimensional noise reduction processing, that is, the three-dimensional noise reduction processing and the one-dimensional / 2-dimensional noise reduction processing are performed in series in this order. In some cases, the noise reduction effect can be enhanced.

(Noise reduction processing apparatus of the second embodiment)
With reference to FIG. 4, the noise reduction processing apparatus of 2nd Embodiment is demonstrated. FIG. 4 is a schematic configuration diagram for explaining the noise reduction processing device of the second embodiment.

  The noise reduction processing device 12 of the second embodiment is different from the noise reduction processing device 10 of the first embodiment in the functions of the motion determination unit 32, the three-dimensional noise reduction processing unit 22, and the noise reduction signal generation unit 62. Since the functions of the constituent elements and the connection relationship between the constituent elements are the same as those of the noise reduction processing apparatus 10 of the first embodiment, redundant description will be omitted.

  In the noise reduction processing device 12 of the second embodiment, the motion determination unit 32 compares the difference between the current frame and the image data between the same pixels in the previous frame with the motion determination threshold value Vth under a plurality of conditions, A multi-bit motion determination signal (indicated by an arrow 31a in the figure) indicating a state with and without, and a transition state therebetween is generated.

  As the plurality of conditions, for example, the motion determination unit 32 may have a plurality of first to n (n is an integer of 2 or more) motion determination thresholds Vth (1) to Vth (n). it can. Here, the first to nth motion determination threshold values Vth (1) to Vth (n) are set to become larger in this order, that is, Vth (1) <Vth (2) <. ). In this case, the motion determination signal 31a indicates 0 when the difference ΔV is equal to or smaller than the first motion determination threshold value Vth (1). The motion determination signal 31a indicates 1 when the difference ΔV is larger than the first motion determination threshold value Vth (1) and is equal to or less than the second motion determination threshold value Vth (2). Similarly, in the motion determination signal 31a, the difference ΔV is larger than the kth (k is an integer between 1 and n−1) motion determination threshold Vth (k), and the k + 1th motion determination threshold Vth. In the case of (k + 1) or less, k is indicated. The motion determination signal 31a indicates n when the difference ΔV is larger than the nth motion determination threshold value Vth (n).

  As a result, the motion determination signal 31a indicates a state where there is no motion by “0”, a state where there is a motion by “n”, and a state between a state where there is a motion and a state where there is no motion, that is, the presence or absence of motion. A transition state in which is ambiguous is indicated by “k”. This motion determination signal 31a is branched into two, one (indicated by an arrow 33a in the figure) is sent to the three-dimensional noise reduction processing unit 22, and the other (indicated by an arrow 35a in the figure) is generated as a noise reduction signal. Sent to the unit 62.

  As the three-dimensional noise reduction processing unit 22, a conventionally well-known configuration in which the pixel value after the three-dimensional noise reduction is given by the above calculation formula (1) can be used as in the first embodiment.

  Here, the coefficient α indicating the degree of three-dimensional noise reduction in the three-dimensional noise reduction processing unit 22 is set to a plurality of values according to the maximum value of the motion determination signal 33a. For example, when the maximum value of the motion determination signal 33a is n, the coefficient α may be 0 ≦ αn <... <Αk <... <Α1 <α0 <1. In this case, when the motion determination signal 33a indicates “0”, that is, when there is no motion, the coefficient α takes the maximum value α0, and at this time, the degree of three-dimensional noise reduction is the strongest. On the other hand, when the motion determination signal 33a indicates “n”, that is, when there is motion, the coefficient α takes the minimum value αn, and at this time, the degree of three-dimensional noise reduction is the weakest. In the transition state where the presence or absence of motion is ambiguous, the coefficient α is selected according to the value indicated by the motion determination signal 33a. In this case, the degree of three-dimensional noise reduction is intermediate.

  Note that the three-dimensional noise reduction processing unit 22 may set αn = 0 when it is determined that there is a motion.

  As described above, the three-dimensional noise reduction processing unit 22 sets the level of noise reduction according to the magnitude of the value indicated by the motion determination signal 33a.

  The three-dimensional noise reduction signal (indicated by 21a in the figure) generated by the three-dimensional noise reduction processing unit 22 is branched into three parts (indicated by 23a, 25a, and 27a in the figure), and the storage units 40, 1 and 1 respectively. It is sent to the two-dimensional / two-dimensional noise reduction processing unit 50 and the noise reduction signal generation unit 62.

  The noise reduction signal generation unit 62 can be configured using a circuit having a signal synthesis function. The noise reduction signal generation unit 62 combines the one-dimensional / two-dimensional noise reduction signal 53 and the three-dimensional noise reduction signal 27a to generate a noise reduction signal. The synthesis ratio γ at the time of synthesis is set according to the magnitude of the value indicated by the motion determination signal 35a, and the noise reduction signal is given by the following calculation formula (2).

Noise reduction signal = γ × 1D / 2D noise reduction signal + (1-γ) × 3D noise reduction signal (2)
Here, when the maximum value indicated by the motion determination signal is n, the synthesis ratio γ is given by, for example, m / n. m is a value indicated by the motion determination signal 35a, and is an integer from 0 to n.

  The noise reduction signal generated by the noise reduction signal generation unit 62 is output as an output signal (indicated by an arrow 63 in the figure).

  The one-dimensional / two-dimensional noise reduction signal 53 is obtained by further reducing the one-dimensional / two-dimensional noise reduction processing on the three-dimensional noise reduction processing signal 25a, and the three-dimensional noise depending on the value indicated by the motion determination signal 33a. The degree of reduction has changed.

(Noise reduction processing method of the second embodiment)
A noise reduction processing method according to the second embodiment will be described with reference to FIGS. FIG. 5 is a diagram illustrating a processing flow for explaining the noise reduction processing method according to the second embodiment. FIG. 6 is a timing chart schematically showing each signal in the noise reduction processing method of the second embodiment. 6A to 6C, the horizontal axis indicates the time axis. 6 (A) and 6 (B), the vertical axis represents the signal intensity in arbitrary units.

  Note that the noise reduction processing method of the second embodiment can be implemented using the noise reduction processing device described with reference to FIG. 4, and therefore, here, the noise reduction processing method will also be described with reference to FIG. 4. To do.

  In addition, the noise reduction processing method of the second embodiment includes the step S22 of performing motion determination, the step S32 of generating a three-dimensional noise reduction signal, and the steps S62 and S72 of generating a noise reduction signal according to the method of the first embodiment. Since other processes are the same as those in the first embodiment, a duplicate description may be omitted.

  In S10, the current frame image data is input to the noise reduction processing apparatus 12, and in S22, motion determination is performed using the current frame image data and the previous frame image data.

  In the motion determination in S22, the motion determination unit 32 compares the difference between the image data of the current frame and the image data of the immediately preceding frame with the motion determination threshold value Vth under a plurality of conditions, and whether there is a motion state or no motion state. And a multi-bit motion determination signal indicating the transition state between them. As the plurality of conditions, for example, the motion determination unit 32 may be configured to have first to nth motion determination threshold values Vth (1) to Vth (n) that take large values in this order.

  Here, n is assumed to be 3. That is, the first to third motion determination threshold values Vth (1) to Vth (3) are set so that 0 <Vth (1) <Vth (2) <Vth (3) (FIG. 6A). ).

  In this case, when the difference ΔV is equal to or smaller than the first motion determination threshold value Vth (1), it is determined that there is no motion, and the motion determination signal 31a indicates “0”. On the other hand, when the difference ΔV is larger than the third motion determination threshold value Vth (3), it is determined that there is motion, and the motion determination signal 31a indicates “3”.

  On the other hand, when the difference ΔV is larger than the first motion determination threshold value Vth (1) and not more than the third motion determination threshold value Vth (3), it is determined as a transition state. At this time, when the difference ΔV is larger than the first motion determination threshold value Vth (1) and equal to or less than the second motion determination threshold value Vth (2), the motion determination signal 31a indicates “1”. Similarly, when the difference ΔV is larger than the second motion determination threshold value Vth (2) and equal to or smaller than the second motion determination threshold value Vth (3), the motion determination signal 31a indicates “2”.

  As a result, the motion determination signal 31a is a 2-bit signal that takes a value of 0 to 3 (FIG. 6B).

  Next, in S32, a three-dimensional noise reduction process using the current frame image data and the previous frame image data is performed to generate a three-dimensional noise reduction signal 21a. In this three-dimensional noise reduction process, the strength of the degree of three-dimensional noise reduction is adjusted according to the result of the motion determination indicated by the motion determination signal 33a (31a).

  The pixel value after the three-dimensional noise reduction process is calculated using the above-described calculation formula (1). Here, the coefficient α indicating the degree of three-dimensional noise reduction in the three-dimensional noise reduction processing unit can take a plurality of values according to the maximum value of the motion determination signal.

  For example, when the maximum value of the motion determination signal is n, the coefficient α may be 0 ≦ α3 <α2 <α1 <α0 <1. In this case, when the motion determination signal indicates “0”, that is, when there is no motion, the coefficient α takes the maximum value α0, and at this time, the degree of three-dimensional noise reduction is the strongest. On the other hand, when the motion determination signal indicates “3”, that is, when there is motion, the coefficient α takes the minimum value α3, and at this time, the degree of three-dimensional noise reduction is the weakest. In the transition state where the presence or absence of motion is ambiguous, the coefficient α1 or α2 is selected depending on whether the value indicated by the motion determination signal is “1” or “2”. In this case, three-dimensional noise reduction is performed. The degree of is intermediate.

  As a result of the motion determination, when it is determined that there is a motion, α3 = 0 may be set.

  Thereafter, the processes in S40 and S50 are the same as in the first embodiment.

  Next, in S62, the noise reduction signal generation unit 62 sets the synthesis ratio γ. The synthesis ratio γ is given by, for example, m / n (= γ). Here, n is the maximum value indicated by the motion determination signal 35a. Further, m is a value indicated by the motion determination signal 35a, and is an integer from 0 to n.

  In the process of generating the noise reduction signal in S72, the one-dimensional / two-dimensional noise reduction signal and the three-dimensional noise reduction signal are synthesized with a synthesis ratio γ set according to the magnitude of the value m indicated by the motion determination signal S35a. Generated as a noise reduction signal. At this time, the noise reduction signal is given by, for example, the above calculation formula (2) (FIG. 6C). The noise reduction signal generated in the noise reduction signal generation unit 62 is output from the noise reduction processing device 12 as the output signal 63.

  When n is 3, if the value indicated by the motion determination signal is “0”, the synthesis ratio γ (= m / n) is 0, which is indicated by I in the three-dimensional noise reduction signal (FIG. 6C). ) Is synthesized at a ratio of 1, 1D / 2D noise reduction signals. That is, the noise reduction signal (output signal 63) contributes 0% to the one-dimensional / two-dimensional noise reduction signal.

  If the value indicated by the motion determination signal is “1”, the synthesis ratio γ is 1/3, the 3D noise reduction signal is 2/3, and the 1D / 2D noise reduction signal is synthesized at a ratio of 1/3. Is done. That is, the contribution of the one-dimensional / two-dimensional noise reduction signal (indicated by II in FIG. 6C) in the noise reduction signal is 33%.

  If the value indicated by the motion determination signal is “2”, the synthesis ratio γ is 2/3, the 3D noise reduction signal is 1/3, and the 1D / 2D noise reduction signal is 2/3. Is done. That is, the noise reduction signal contributes 67% of the one-dimensional / two-dimensional noise reduction signal.

  If the value indicated by the motion determination signal is “3”, the synthesis ratio γ is 1, and the 3D noise reduction signal is synthesized with a ratio of 0 and the 1D / 2D noise reduction signal with a ratio of 1. That is, the contribution of the one-dimensional / two-dimensional noise reduction signal is 100% in the noise reduction signal.

  According to the noise reduction device and the noise reduction method of the second embodiment, in addition to the effects of the first embodiment, discontinuity due to a sudden change in data in a transition state near the boundary between a portion with motion and a portion without motion. Therefore, good image quality can be obtained.

  Here, the configuration example has been described in which the motion determination unit has a plurality of motion determination thresholds and generates a multi-bit motion determination signal in the motion detection process, but the present invention is not limited to this example.

  For example, the motion determination unit may have one motion determination threshold value Vth and other threshold determination conditions as a plurality of conditions.

  The motion determination in this case will be described with reference to FIG. FIG. 7 is a schematic diagram for explaining another example of motion determination according to the second embodiment.

  First, a comparison is made for each pixel with the motion determination threshold value Vth of the difference between the image data of the current frame and the image data of the immediately preceding frame. As a result of the comparison, 0 is indicated when the difference between the pixels for motion determination (hereinafter also simply referred to as target pixels) is equal to or less than the motion determination threshold value Vth. On the other hand, if the difference between the corresponding pixels is larger than the motion determination threshold value Vth, the motion determination of the difference between the image data of the current frame and the image data of the immediately preceding frame for the pixels around the pixel subjected to motion determination. A comparison is made with the threshold value Vth, and according to the number of pixels whose difference is larger than the motion determination threshold value Vth, if the number is large, the value indicated by the motion determination signal is increased. The value indicated by the signal can be reduced.

  Here, as an example, a case will be described in which one pixel on each of the left and right adjacent in the horizontal direction is used as a pixel around a target pixel for motion determination. In the following description, pixels adjacent to the left side of the target pixels 90a, 90b, 90c and 90d are referred to as left pixels 92a, 92b, 92c and 92d, and pixels adjacent to the right side are right pixels 94a, 94b, 94c and 94d. Called. In the following description, the target pixels 90a, 90b, 90c and 90d are represented by reference numeral 90, the left pixels 92a, 92b, 92c and 92d are represented by reference numeral 92, and the right pixels 94a, 94b are represented. 94c and 94d may be represented by reference numeral 94.

When the difference V _O in the target pixel 90a is equal to or less than the motion determination threshold value Vth (Vo ≦ Vth), it is determined that there is no motion, and the motion determination signal 31a indicates “0”. In this case, the difference _{V L} in the left pixel 92a, the difference _{V R} is not considered in the right pixel 94a (FIG. 7 (A)).

When the difference V _O in the target pixel 90 is larger than the motion determination threshold value Vth (Vo> Vth), the difference between the left pixel 92 and the right pixel 94 is compared with the motion determination threshold value Vth.

Left pixel 92b and any difference value _{V L} and _{V R} is the right pixel 94b when: the motion judgment threshold Vth _{(V L} ≦ Vth and _{V R} ≦ Vth), among the two pixels around, the difference is Since there are no pixels larger than the motion determination threshold value Vth, it is determined that the possibility of motion is low (low possibility). At this time, the motion determination signal 31a indicates “1” (FIG. 7B).

When the difference values V _L and V _R in the left pixel 92d and the right pixel 92d are both greater than the motion determination threshold Vth (V _L > Vth and V _R > Vth), the difference between the two surrounding pixels is Since there are two pixels larger than the motion determination threshold value Vth, it is determined that the possibility of motion is high (high possibility). At this time, the motion determination signal 31a indicates “3” (FIG. 7D).

Furthermore, one of the difference values V _L and V _R in the left pixel 92c and the right pixel 94c is larger than the motion judgment threshold Vth, the other is less than the motion judgment threshold value Vth, the two pixels around Among them, since there is one pixel whose difference is larger than the motion determination threshold value Vth, it is determined that the possibility is low and high possibility (middle possibility), and the motion determination signal 31a indicates “2”. (FIG. 7C). In FIG. 7 (C), the greater than the difference _{V L} motion judgment threshold Vth of the left pixel 92c _(V L> Vth), if the difference _{V R} in the right pixel 94c is less than the motion judgment threshold value Vth ( V _R ≦ Vth).

  Here, although an example using three pixels of the target pixel 90, the left pixel 92, and the right pixel 94 has been described, the present invention is not limited to this. The motion determination may be performed according to the number of pixels exceeding the motion determination threshold value Vth using two or more pixels each present in the left-right direction of the target pixel. Further, one or two or more pixels that exist in the vertical direction with respect to the vertical direction of the target pixel may be used. Further, both the horizontal direction and the vertical direction may be combined with respect to the target pixel.

It is a schematic block diagram of the noise reduction processing apparatus of 1st Embodiment. It is a figure which shows the processing flow of the noise reduction processing method of 1st Embodiment. It is a timing chart which shows typically each signal in a 1st embodiment. It is a schematic block diagram of the noise reduction processing apparatus of 2nd Embodiment. It is a figure which shows the processing flow of the noise reduction processing method of 2nd Embodiment. It is a timing chart which shows typically each signal in a 2nd embodiment. It is a schematic diagram for demonstrating the other example of the motion determination of 2nd Embodiment. It is a schematic block diagram (the 1) of the conventional noise reduction processing apparatus. It is a schematic block diagram (the 2) of the conventional noise reduction processing apparatus.

Explanation of symbols

10, 12 Noise reduction processing device
20, 22 3D noise reduction processing unit 30, 32 Motion determination unit 40 Storage unit 50 1D / 2D noise reduction processing unit 60, 62 Noise reduction signal generation unit

Claims (8)

A three-dimensional noise reduction processing unit that receives image data, performs a three-dimensional noise reduction process on the image data, and outputs a three-dimensional noise reduction signal;
A storage unit for storing the three-dimensional noise reduction signal for one frame;
A motion determination unit that determines the presence or absence of motion of image data between the same pixels in the preceding and following frames and outputs a motion determination signal;
A one-dimensional / two-dimensional noise reduction processing unit that performs one or both of one-dimensional noise reduction processing and two-dimensional noise reduction processing on the three-dimensional noise reduction signal and outputs the result as a one-dimensional / 2-dimensional noise reduction signal. When,
A noise reduction signal generation unit that generates a noise reduction signal including the three-dimensional noise reduction signal and the one-dimensional / two-dimensional noise reduction signal at a ratio according to a result of determination of presence / absence of motion in the motion determination unit; With
When image data of the current frame is input to the three-dimensional noise reduction processing unit and the motion determination unit,
Image data of the immediately previous frame immediately before the current frame is sent from the storage unit to the three-dimensional noise reduction processing unit and the motion determination unit,
The motion determination unit compares the difference in image data between the same pixels of the current frame and the immediately preceding frame with a threshold value under a plurality of conditions, a state with motion and a state without motion, and a transition state between are shown, and generates a motion determination signal of a plurality of bits, the motion determination signal is output to said three-dimensional noise reducing device and said noise reduction signal generating unit as a motion determination signal of the current frame,
The three-dimensional noise reduction processing unit performs a three-dimensional noise reduction process between the same pixels of the current frame and the immediately preceding frame according to a result of the motion determination signal of the current frame, and generates a three-dimensional noise reduction signal. A noise reduction processing device characterized in that, in addition to the output, the level of noise reduction is set according to the magnitude of the value indicated by the motion determination signal . The motion determination unit has first to n (n is an integer of 2 or more) threshold values that are larger in this order,
The motion determination signal indicates 0 when the difference is equal to or less than a first threshold, the difference is greater than a threshold of the kth (k is an integer not less than 1 and not more than n−1), and k + 1 of it indicates k if smaller than the threshold value, and the difference noise reduction processing device according to claim 1 is greater than the threshold value of the n that said to exhibit n. The motion determination unit has a threshold value of 1, and performs a comparison between the threshold value and the difference in image data between the same pixels in the current frame and the previous frame for each pixel,
The motion determination signal is
When the difference in the target pixel to be compared is equal to or less than the threshold value, 0 is indicated,
When the difference in the target pixel is larger than the threshold value, the difference between the threshold value and the difference in image data between the same pixels in the current frame and the immediately preceding frame for a plurality of pixels around the target pixel According to the number of pixels in which the difference is greater than the threshold value, the value indicated by the motion determination signal is increased if the number is large, while the value indicated by the motion determination signal is increased if the number is small. The noise reduction processing apparatus according to claim 1 , wherein the noise reduction processing apparatus is reduced. The 3-dimensional noise reducing device, when it is determined that there is motion, the noise reduction processing device according to any one of claims 1 to 3, characterized in that does not perform a three-dimensional noise reducing process. The process of inputting image data of the current frame subject to noise reduction processing,
Determining whether or not there is motion of image data between the same pixels for the current frame and a frame immediately before the current frame;
A process of generating a three-dimensional noise reduction signal by performing a three-dimensional noise reduction process between the same pixels of the current frame and the immediately preceding frame according to the determination result of the presence or absence of movement;
Storing the three-dimensional noise reduction signal in the storage unit as image data of the immediately preceding frame;
Performing one or both of a one-dimensional noise reduction process and a two-dimensional noise reduction process on the three-dimensional noise reduction signal to generate a one-dimensional / two-dimensional noise reduction signal;
A step of generating and outputting a noise reduction signal including the three-dimensional noise reduction signal and the one-dimensional / two-dimensional noise reduction signal at a ratio according to the result of the determination of the presence or absence of the movement ,
In the process of determining the presence or absence of movement, the difference between the image data between the same pixels of the current frame and the immediately preceding frame is compared with a threshold value under a plurality of conditions, and the state with and without movement A multi-bit motion determination signal indicating the transition state of
The noise reduction processing method characterized in that, in the process of generating the three-dimensional noise reduction signal, the degree of noise reduction is set according to the magnitude of the value indicated by the motion determination signal . In the process of determining the presence / absence of the movement, when the difference is less than or equal to the first threshold value, the difference is 0 or less with respect to the first to nth threshold values (n is an integer of 2 or more) that increase in this order. When the difference is larger than a threshold value of kth (k is an integer not less than 1 and not more than n−1) and smaller than the k + 1th threshold value, k is indicated, and the difference is nth 6. The noise reduction processing method according to claim 5 , wherein the motion determination signal indicating n is generated when larger than a threshold value. In the process of determining the presence or absence of the movement, the difference between the image data between the same pixels of the current frame and the previous frame is compared with a threshold value of 1 for each pixel,
When the difference in the target pixel to be compared is less than or equal to the threshold value, the value indicated by the motion determination signal is set to 0,
When the difference in the target pixel is larger than the threshold value, the difference between the threshold value and the difference in image data between the same pixels in the current frame and the immediately preceding frame for a plurality of pixels around the target pixel According to the number of pixels in which the difference is greater than the threshold value, the value indicated by the motion determination signal is increased if the number is large, while the value indicated by the motion determination signal is increased if the number is small. 6. The noise reduction processing method according to claim 5 , wherein the noise reduction processing method is reduced. In the process of generating the three-dimensional noise reducing signal, a result of the determination, when it is determined that there is motion, to any one of claims 5-7, characterized in that it does not perform the processing of noise reduction The noise reduction processing method as described.

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