JP5014277B2 - Focus auxiliary signal processing device - Google Patents

Description

  The present invention relates to a focus assist signal processing apparatus, and more particularly, to a technique that has a viewfinder as a focus assist mechanism when photographing using a television camera and displays a focus assist signal for focus adjustment on the viewfinder.

  Conventionally, various methods are known as a camera focus assist mechanism. For example, in a film camera, a range finder method using the principle of triangulation, a method using a single-lens reflex camera or the like that can actually visually confirm and confirm an optical image passing through a lens to be photographed are known. Although few TV cameras have an optical viewfinder, a small CRT or LCD monitor is attached to the camera, and the photographer himself adjusts the focus while viewing the captured image displayed on the screen. . In the case of a low-definition standard TV, the image for focus adjustment could be confirmed with the small screen viewfinder, but in the case of a high-definition TV with a high resolution, the image for focus adjustment can be obtained simply by looking at the small screen. It has become difficult to accurately confirm. For this reason, the lens system for screen enlargement is devised, processing to emphasize high frequencies such as peaking processing, and flickering so that these signals are easy to detect helps to adjust the focus on the viewfinder. I was going.

  As a conventional technique, for example, as described in Patent Document 1, a technique for performing signal processing for displaying an image matched with visual characteristics so that a focused part can be easily understood is disclosed. . Further, for example, as described in Patent Document 2, in a high-definition imaging method such as high vision, in order to improve the visibility in the viewfinder, the high-frequency component of the captured image is modulated, A technique for generating a focus assist signal by adding to or subtracting the video signal is also disclosed.

  Conventionally, as shown in FIG. 8, in order to improve the visibility of the position of the focus point, a high frequency component is extracted from the captured image and amplified (boost frequency in FIG. 8), and then the signal superimposed on the original video signal is displayed on the viewfinder. The method of displaying above is used. These high-frequency component extractions can be realized, for example, by applying a 3 × 3 tap filter to an image or using a FIR filter (Finite Impulse Response Filter). Currently, in existing video systems such as high-definition, a small display device capable of displaying an image with a resolution almost the same as a captured image has been developed as a viewfinder. Therefore, with the above method, the focus adjustment can be performed almost accurately with the viewfinder attached to the camera head.

Japanese Patent Publication No. 6-28392 Japanese Patent Publication No.7-87539

  However, in digital cinema and Super Hi-Vision that handle even high-frequency video signals, there is no sufficiently high-definition viewfinder at the moment when focusing with a higher-definition camera. Very difficult to do. This is a case where the high frequency signal component of the captured image is superimposed on the original image using the method described in Patent Document 2 and then displayed on a small display device attached to the camera head by a method such as sub-sampling. However, the high frequency signal superimposed as the auxiliary signal for focus adjustment cannot be confirmed accurately. This is because the display device itself does not have sufficient resolution, and as shown in FIG. 9, the baseband signal has a high frequency signal component folded back into the displayable frequency band of the monitor. It is.

  Further, when focus adjustment is performed with an ultra-high-definition camera, there is a possibility that an out-of-focus image may be shot unless the focus adjustment is strictly performed. Therefore, there is a need for a camera system including a display device that can perform focus adjustment with high accuracy even on a low-resolution monitor attached to the camera head.

  Therefore, in order to solve the above problems, the object of the present invention is to extract and display contour information from an ultra-high-definition original image in a form that can be easily viewed on a low-resolution monitor such as a viewfinder. An object of the present invention is to provide a focus auxiliary signal processing device capable of performing focus adjustment.

In order to solve the above-mentioned problems, the invention of claim 1 inputs a video signal of a high-definition image in a digital cinema or Super Hi-Vision of a subject photographed by an imaging device , processes the video signal, and adjusts the focus. In a focus auxiliary signal processing device that generates a signal for assisting image display and displays an image of the subject on a display device, a signal of a pass band and a gain adjusted by a photographer who performs shooting using the imaging device is input. A high-pass filter that extracts a high-frequency signal component that exceeds a frequency band capable of image display on the display device from the video signal of the high-definition image based on the adjustment signal; and the high-definition from the image video signal, a low pass filter for extracting a low-frequency signal component of the image displayable frequency band in the display device, the high frequency A noise removing unit that removes isolated points from the high-frequency signal component extracted by the overfilter, and a thickening unit that performs thickening processing on the high-frequency signal component from which the isolated points are removed by the noise removing unit, Sub-sample processing is performed on the high-frequency signal component that has been subjected to thickening processing by the thickening section, and converted to a signal component that can be displayed on the display device, and converted by the subsample section. And a synthesizing unit that synthesizes the low-frequency signal component extracted by the low-pass filter and outputs the synthesized signal component to the display device, and adjusts the focus according to the passband and gain adjustment by the photographer. The high-pass filter, the noise removing unit, the thickening unit, and the like so that the aliasing component corresponding to the high-frequency signal component for assisting the adjustment appears on the display of the display device. The sub-sample unit, and generating an image displayable signal components in the display device.

According to a second aspect of the present invention, a video signal of a subject photographed by the imaging device is input, a signal for assisting focus adjustment is generated by processing the video signal, and the image of the subject is displayed on the display device. In the focus auxiliary signal processing device to be displayed, a high-pass filter that extracts from the video signal a high-frequency signal component that exceeds a frequency band capable of image display on the display device, and an image on the display device from the video signal. A low-pass filter that extracts a low-frequency signal component of a displayable frequency band, and a sub-sampling process that changes a sampling phase for each frame for the high-frequency signal component extracted by the high-pass filter, Subsampler for converting into signal component that can display image in display device, and signal component converted by subsampler The synthesizes the low-frequency signal component extracted by the low-pass filter, characterized by comprising a combining unit for outputting to the display device.

The invention according to claim 3 is the focus auxiliary signal processing device according to claim 1, wherein the sub-sampling unit changes the sampling phase for each frame when sub-sampling the high-frequency signal component. And

  As described above, according to the present invention, accurate focus adjustment is performed by extracting and displaying contour information from an ultra-high-definition original image in a form that is easily visible on a low-resolution monitor such as a viewfinder. be able to.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
[Focus auxiliary signal processing system]
First, the configuration of the focus auxiliary signal processing system and the processing of each component will be described. FIG. 1 is a block diagram showing a configuration of a focus auxiliary signal processing system according to an embodiment of the present invention. The focus auxiliary signal processing system includes an imaging device 1, a focus auxiliary signal processing device 2, and a display device 3.

  The imaging device 1 captures an original image and outputs the original image as a video signal to the focus auxiliary signal processing device 2. Examples of the imaging device 1 include a television camera. In this embodiment, a case where a high-definition television camera is used will be described as an example.

  The focus auxiliary signal processing device 2 inputs a video signal from the imaging device 1, processes the input video signal, and outputs it to the display device 3. Specifically, the contour information is extracted from the ultra-high definition original image in a form that is easily visible to the display device 3.

  The display device 3 displays the video signal output from the focus auxiliary signal processing device 2. Examples of the display device include a low-resolution monitor. In the present embodiment, a case where a viewfinder is used will be described as an example. Then, the photographer performs focus adjustment using the video displayed on the display device 3.

  In the embodiment of the present invention, the resolution of the display device 3 (viewfinder) is assumed to be 1/4 with respect to the resolution of the imaging device 1 (high-definition television camera).

[Focus auxiliary signal processor]
Next, the configuration of the focus signal processing device 2 shown in FIG. 1 and the processing of each component will be described. FIG. 2 is a block diagram showing a configuration of the focus auxiliary signal processing apparatus according to the embodiment of the present invention. The focus auxiliary signal processing apparatus includes a high-pass filter 21, a low-pass filter 22, a noise removal unit 23, a thick line unit 24, a subsample unit 25, a synthesis unit 26, and a delay line 27.

  The high-pass filter 21 receives a video signal from the imaging device 1, extracts a high-frequency signal component that occurs when the image is in focus and exceeds the frequency band that can be displayed on the display device 3, and outputs the high-frequency signal component to the noise removing unit 23. To do. For example, as shown in FIG. 3, the high-pass filter 21 extracts a signal component having a spatial frequency fc or higher as a high-frequency signal component. Note that the imaging device 1 and the display device 3 can input and output a two-dimensional image, but for the sake of simplicity, the one-dimensional frequency component in the horizontal direction or the vertical direction will be described. In FIG. 3, the frequency (1/2 of the spatial sampling frequency in the pixel matrix monitor) that can be displayed on the display device 3 (here, a low-resolution monitor) is fn0, and the image is taken by the imaging device 1 (here, a high-definition camera). Let fn3 be the frequency band of the video component. The same applies to FIGS. 4 and 5.

  In the focus auxiliary signal processing system according to the embodiment of the present invention, as shown in FIG. 3, for example, a system in which fn3 has a frequency band four times that of fn0 is targeted, but the present invention is not limited to this. Any system that satisfies fn3> fn0 may be used.

  In addition, the passband of the high-pass filter 21 and the amplitude (gain) of the high-frequency signal component obtained at this time are the most in-focus positions by the photographer by the lens focus adjustment function on the display device 3. It is adjusted to make it easier to understand. The pass band and gain adjustment signal are input to the high pass filter 21. The high pass filter 21 extracts a high pass signal component from the video signal based on the pass band and the gain adjustment signal.

  The low-pass filter 22 receives a video signal from the imaging device 1, extracts a low-frequency signal component that does not generate a folding signal in the display device 3, and outputs the low-frequency signal component to the synthesis unit 26. For example, as shown in FIG. 4, the low-pass filter 22 extracts a signal component having a spatial frequency fa or less as a low-frequency signal component.

  The noise removing unit 23 receives a high-frequency signal component from the high-pass filter 21 and removes isolated points from the high-frequency signal component. The noise removing unit 23 can perform, for example, using a median filter when removing isolated points. Then, the noise removal unit 23 outputs the high-frequency signal component from which the isolated points are removed to the thickening unit 24.

  The thickening unit 24 receives the high-frequency signal component from which the isolated points are removed from the noise removing unit 23, performs the thickening process, and outputs the high-frequency signal component subjected to the thickening process to the sub-sampling unit 25. . Specifically, in the sub-sample unit 25, when the sub-sample process for selecting one for every four pixels is performed, the thickening process at least four times is performed. The thickening unit 24 can perform the thickening using, for example, morphological processing.

  The sub-sampling unit 25 receives the high-frequency signal component that has been subjected to the thickening process from the thickening unit 24, and converts the high-frequency signal component signal into a signal component that can be displayed on the display device 3. The processing is performed, and the low-frequency signal component subjected to the sub-sample processing is output to the synthesis unit 26. Here, “subsample” means thinning out the number of samples. For example, the sub-sampling unit 25 can convert a high-frequency signal component into a low-frequency signal component by selecting one for every four pixels.

  As another sub-sampling process, the sub-sampling unit 25 uses the sample phase adjustment signal to sample the high-frequency video signal instead of outputting the low-frequency signal component subjected to the sub-sampling process as described above. The phase is changed for each frame, a low frequency false signal that changes with time is generated, and the low frequency false signal is output to the synthesis unit 26. In this case, it is possible to pass through without performing the thickening process by the thickening unit 24 described above. Specifically, when the sub-sampling unit 25 performs sub-sampling for every four pixels as shown in FIG. 6, the sub-sample unit 25 calculates a pixel value for each pixel position, and as shown in FIG. By assigning a frame for each position, the sampling phase is changed for each frame. That is, at each pixel position, a set of pixel values represented by 1 is a first frame, a set of pixel values represented by 2 is a second frame, and a set of pixel values represented by 3 is a third frame. A set of pixel values represented by 4 is set as a fourth frame, and pixel values for each frame are sequentially output from the first frame to the fourth frame as a low-frequency false signal.

  The synthesizing unit 26 receives the low-frequency signal or the low-frequency pseudo signal (high-frequency signal component) subjected to the sub-sample processing from the sub-sampling unit 25, and converts the low-frequency signal component from the low-pass filter 22 via the delay line 27. input. The synthesizing unit 26 adjusts the delay time of the low-frequency signal component from the low-pass filter 22 using the delay line 27, and the high-frequency signal component from the sub-sample unit 25 and the low-frequency signal from the low-pass filter 22 are adjusted. Phase adjustment with the signal component is performed, and the spatial positions of the high-frequency signal component and the low-frequency signal component corresponding to the edge of the subject are matched. Then, as shown in FIG. 5, the synthesizing unit 26 superimposes the high-frequency signal component from the sub-sample unit 25 and the low-frequency signal component from the low-pass filter 22 in a displayable video band. To do. Then, the synthesis unit 26 outputs a synthesized signal of the high frequency signal component and the low frequency signal component to the display device 3.

  The photographer adjusts the focus to the focus position where the highest frequency signal component appears, while checking the display device 3 on which such an image is displayed, thereby adjusting the camera focus.

  As described above, according to the focus auxiliary signal generation device 1 according to the embodiment of the present invention, a high-definition video signal is divided into a high-frequency component and a low-frequency component, and a high-frequency signal component necessary for focus adjustment is obtained. Can be extracted and synthesized by superimposing with the low-frequency signal component and displayed on a low-resolution monitor. For this reason, while observing the video signal shot with a high-definition camera on a low-resolution monitor, the video signal corresponding to the high-frequency signal component necessary for focus adjustment can also be detected, and the camera can be adjusted on the low-resolution monitor. Is possible.

  Further, in the focus auxiliary signal processing device 2 according to the embodiment of the present invention, the high-pass filter 21 determines the high-frequency signal component based on the input pass-band of the high-pass filter and the amplitude of the obtained high-frequency signal component. Extraction can be performed. For this reason, the photographer can arbitrarily change the high-frequency signal component to be extracted.

  Further, in the focus auxiliary signal processing device 2 according to the embodiment of the present invention, the sub-sampling unit 25 can perform sub-sampling processing because the high-frequency signal component is converted into a signal component that can be displayed on the display device 3. For this reason, the aliasing component generated by sub-sampling the high frequency signal component can be displayed superimposed on the low frequency signal component.

  Further, in the focus auxiliary signal processing device 2 according to the embodiment of the present invention, the noise removing unit 23 can remove isolated points from the high-frequency signal component extracted by the high-pass filter 21. If the high-frequency signal component is sub-sampled as it is, the high-frequency signal component may be lost, but the high-frequency signal component can be held by the processing of the noise removing unit 23.

  Further, in the focus auxiliary signal processing device 2 according to the embodiment of the present invention, the thickening unit 24 can input the high-frequency signal component from which the isolated point is removed from the noise removing unit 23 and perform the thickening process. For this reason, the amount of aliasing components of the high frequency signal component appearing in the low frequency signal component after the sub-sampling can be increased.

  In the focus auxiliary signal processing apparatus 2 according to the embodiment of the present invention, the sub-sampling unit 25 can change the sampling phase for each frame when the high-frequency video signal is sub-sampled. By performing such processing, it becomes easier to detect the presence or absence of a high-frequency signal component in the video displayed on the display device 3.

  The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the technical idea thereof. For example, in the above-described embodiment, for the sake of simplicity, the description has been given as the one-dimensional signal processing performed on the frequency component in the horizontal direction, but naturally the same effect can be obtained also in the horizontal-vertical two-dimensional signal processing.

  In the embodiment, the resolution of the low-resolution monitor used as the viewfinder is set to 1/4 with respect to the output signal of the camera. How much low-resolution monitor can be used for the viewfinder is related to how much the position on the screen needs to be able to confirm the focus position, and does not affect the essential principle of the present invention.

It is a block diagram which shows the structure of the focus auxiliary | assistant signal processing system by embodiment of this invention. It is a block diagram which shows the structure of the focus auxiliary | assistant signal processing apparatus by embodiment of this invention. It is a figure for demonstrating the extraction process of the high-pass signal component of the high-pass filter by embodiment of this invention. It is a figure for demonstrating the extraction process of the low-pass signal component of the low-pass filter by embodiment of this invention. It is a figure for demonstrating the synthetic | combination process of the high frequency signal component of a synthetic | combination part by embodiment of this invention, and a low frequency signal component It is a figure for demonstrating the pixel value calculation process for every position of the pixel of the subsample part by embodiment of this invention. It is a figure for demonstrating the frame allocation process for every position of the pixel of the subsample part by embodiment of this invention. It is a figure for demonstrating the production | generation process of the conventional focus auxiliary signal (the 1). It is a figure for demonstrating the production | generation process of the conventional focus auxiliary signal (the 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Focus auxiliary | assistant signal processing apparatus 3 Display apparatus 21 High-pass filter 22 Low-pass filter 23 Noise removal part 24 Thickening part 25 Subsampling part 26 Synthesis | combination part 27 Delay line

Claims (3)

Input a video signal of a high-definition image in a digital cinema or Super Hi-Vision of a subject photographed by an imaging device , process the video signal to generate a signal for assisting focus adjustment, and image the subject In the focus auxiliary signal processing device that displays the image on the display device,
Input a passband and gain signal adjusted by a photographer who performs shooting using the imaging device, and display an image on the display device from the video signal of the high-definition image based on the adjustment signal A high-pass filter that extracts high-frequency signal components that exceed a certain frequency band,
A low-pass filter that extracts, from the video signal of the high-definition image, a low-frequency signal component in a frequency band in which an image can be displayed on the display device;
A noise removing unit for removing isolated points from the high-frequency signal component extracted by the high-pass filter;
A thickening unit that performs a thickening process on the high-frequency signal component from which isolated points have been removed by the noise removing unit;
A sub-sampling unit that performs sub-sampling processing on the high-frequency signal component that has been subjected to thickening processing by the thickening unit, and converts the signal into a signal component that can be displayed on the display device;
A synthesis unit that synthesizes the signal component converted by the sub-sample unit and the low-frequency signal component extracted by the low-pass filter and outputs the synthesized signal component to the display device;
In accordance with the adjustment of the passband and gain by the photographer, the high-pass filter, the noise removing unit, and the aliasing component corresponding to the high-frequency signal component for assisting the focus adjustment appear on the display of the display device. A focus auxiliary signal processing device characterized in that a signal component capable of image display in the display device is generated by a thickening portion and a subsample portion . In a focus auxiliary signal processing device that inputs a video signal of a subject photographed by an imaging device, generates a signal for assisting focus adjustment by processing the video signal, and displays the image of the subject on a display device.
  A high-pass filter that extracts from the video signal a high-frequency signal component that exceeds a frequency band in which an image can be displayed on the display device;
  A low-pass filter that extracts, from the video signal, a low-frequency signal component of a frequency band in which an image can be displayed on the display device;
  A sub-sampling unit that performs sub-sampling processing that changes a sampling phase for each frame on the high-frequency signal component extracted by the high-pass filter, and converts the signal into a signal component that can be displayed on the display device;
  A combining unit that combines the signal component converted by the sub-sample unit and the low-frequency signal component extracted by the low-pass filter, and outputs the combined signal to the display device;
A focus auxiliary signal processing apparatus comprising: The focus auxiliary signal processing device according to claim 1,
The sub-sampling unit changes the sampling phase for each frame when the high-frequency signal component is sub-sampled .

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