JP2019220925A - Imaging apparatus and video output method - Google Patents

Abstract

To restrain increase in transmission amount and calculation amount of a video, while restraining degradation of a display video, when acquiring a video having a relatively high frame rate and transmitting to a display device.SOLUTION: An imaging apparatus 10 includes: an imaging device 11 acquiring captured video data of a high frame rate exceeding the human visual time sensitivity by imaging; and a video output part 12 for generating display video data of a second gray scale of lower gradation value than that of a first gray scale normally obtained from the captured video data. The video output part 12 includes: an operation part 13 as a noise addition part for adding summation noise to the captured video data, so that summation of noise levels of respective luminance values becomes uniform over the entire luminance values of the captured video data; a noise generator 14 and an adder 15; and a quantizer 16 as a modulation section for converting the video data after added with the summation noise into the display video data of the second gray scale.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an imaging device and a video output method used for a video display system or the like suitable for displaying a video having a relatively high frame rate.

  A video display system that performs image processing and transmission on a video signal of a moving image and displays a video on a display device is designed to operate at a frame rate of 60 fps (frame per seconds) or less in consideration of human vision. Generally, it is done. In such a video display system, a certain amount of delay occurs in the entire system due to execution of each process of imaging, image processing, and transmission until the video acquired by the imaging device is displayed on the display device. become. For example, when the frame rate is 60 fps, the time per frame is about 16.6 ms, and a delay of, for example, about 100 ms may occur as a video display delay.

  Such a delay in video display with respect to the video output captured by the imaging device may adversely affect the operation of the system. For example, when controlling a robot arm and grasping an irregularly moving object while watching an image from a distance, the delay in the image can be a factor that hinders stable operation. desired. Eliminating delays in video display is also beneficial in video display systems used for endoscopic surgery and remote surgery using real-time video, remote control of disaster relief robots, and the like.

  On the other hand, a technology that suppresses the delay of video display by applying a relatively high frame rate (for example, 480 fps) to the video is also supposed. However, if the frame rate is simply increased, the transmission amount and the calculation This leads to an increase in the amount.

  As a technique for suppressing the transmission amount while maintaining a high resolution of an image, for example, regarding an image captured by a surveillance camera, attention is paid to a vicinity of a door where a person enters and exits, and a target monitoring area to be monitored is increased. It is known to display at the frame rate and transmit at a low frame rate in consideration of the effective use of network bandwidth, such as areas where plants are placed and walls, etc. I have.

JP 2008-219484 A

  In the prior art described in Patent Document 1, a high frame rate of about 30 fps is assumed. Here, when a higher frame rate (for example, 480 fps) is applied to maintain the high resolution of the video, even if the application of the high frame rate is a part of the image such as the monitoring area of interest. , The amount of transmission and the amount of calculation can be problematic.

  According to the present disclosure, when acquiring a video having a relatively high frame rate and transmitting the acquired video to a display device, it is possible to suppress an increase in a transmission amount and a calculation amount of the video while suppressing a decrease in quality of the displayed video. It is an object of the present invention to provide an imaging device and a video output method capable of performing the above.

  The present disclosure relates to an imaging device that acquires imaged video data at a high frame rate exceeding human visual time sensitivity by imaging, and a second grayscale having a grayscale value smaller than a first grayscale normally obtained from the captured video data. And a video output unit for generating and outputting the display video data of the image data, wherein the video output unit makes the sum of the noise levels of the respective luminance values uniform over the entire luminance value of the captured video data. A noise adding unit that adds an additional noise to the captured video data; and a modulator that converts the video data to which the additional noise has been added into the second-gradation display video data. Provide equipment.

  Further, the present disclosure also includes a step of acquiring captured image data of a high frame rate exceeding a human visual time sensitivity captured by an imaging device, and a sum of noise levels of each luminance value over the entire luminance value of the captured image data. Adding an additional noise to the captured video data so as to be uniform, and using the video data to which the additional noise has been added, by using a first gradation normally obtained from the captured video data. Also, the present invention provides a video output method, comprising the steps of: generating second grayscale display video data having a small grayscale value; and outputting the second grayscale display video data to a display device.

  According to the present disclosure, when acquiring a video having a relatively high frame rate and transmitting the acquired video to a display device, it is possible to suppress a decrease in the quality of the displayed video and to suppress an increase in a video transmission amount and a calculation amount. .

FIG. 2 is a block diagram showing a first example of a configuration of a video display system including the imaging device according to the present embodiment. FIG. 9 is a diagram illustrating an example of noise characteristics in the imaging device according to the present embodiment. FIG. 4 is a diagram showing an operation example of adding noise to video data in the imaging device according to the present embodiment. FIG. 2 is a block diagram showing a second example of the configuration of the video display system including the imaging device according to the present embodiment. FIG. 10 is a diagram illustrating an example of a relationship between an output luminance value of a video signal and a noise level in the imaging device, and illustrating a virtual state in which noise does not occur. FIG. 5 is a diagram illustrating an example of a relationship between an output luminance value of a video signal and a noise level in the imaging apparatus, and illustrating a state of an actual imaging device in which optical shot noise occurs. FIG. 9 is a diagram illustrating an operation example of the imaging device of the comparative example. FIG. 4 is a diagram illustrating an operation example of the imaging device according to the present embodiment;

  Hereinafter, each embodiment that specifically discloses the configuration according to the present disclosure will be described in detail with reference to the drawings as appropriate. However, an unnecessary detailed description may be omitted. For example, a detailed description of well-known matters and a repeated description of substantially the same configuration may be omitted. This is to prevent the following description from being unnecessarily redundant and to facilitate understanding of those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the claimed subject matter.

  In the present embodiment, an example of the configuration of a video display system that displays video having a relatively high frame rate is shown, and an example of the configuration and operation of an imaging device that acquires and transmits video at a high frame rate in this video display system Will be described. As an image display system with a high frame rate, for example, a configuration for displaying an image with a frame rate of 480 fps will be described. As the frame rate, a value sufficiently higher than 30 fps to 60 fps used for normal video, such as 480 fps and 960 fps, is used. This embodiment shows a configuration example in which a delay is suppressed by displaying a video at a high frame rate, and an increase in a video transmission amount and a calculation amount is suppressed.

  Here, a time characteristic of a contrast sensitivity function (CSF) of the visual system will be described. Regarding the time frequency of the CSF, the time frequency at which flicker is not perceived when the contrast of the stimulus is inverted is called a critical fusion frequency (CFF). It corresponds to the time frequency. The human CFF is set to about 50 Hz, and 60 to 120 Hz is considered to be a limit at which a change in contrast can be detected even at high speed. In this specification, the upper limit value that can be perceived by humans is referred to as human visual time sensitivity (temporal resolution of visual information processing). For a high-speed video having a frame rate of, for example, 480 fps or more that exceeds the human visual time sensitivity, the human perceives the video as an afterimage over a plurality of frames.

  In consideration of such human visual characteristics, in the present embodiment, random noise is added to video data of a relatively high frame rate captured by the imaging device, and the number of bits of the luminance value is reduced. Transmission is performed with the gradation lowered. In this case, so-called dither processing is performed by adding random noise while reducing the tone value of the video data, and the video data is output. Thereby, while reducing the data amount of the video data, the grayscale component lost by the reduction of the grayscale value is restored by the afterimage of a plurality of frames by the human eyes to give a pseudo grayscale, Suppress deterioration in the quality of the displayed video.

  It is known that stochastic resonance occurs by adding random noise to a signal. In the present embodiment, by utilizing stochastic resonance, a random noise is intentionally added to video data, and a signal component less than a threshold value can be detected with a certain probability. Restores lost tone components.

  In the present embodiment, the noise level of random noise added to video data (that is, the amplitude range of added noise) is adjusted in consideration of light shot noise as an example of intrinsic noise generated in the imaging device. In this case, the amplitude range of the added noise is changed so that the sum of the noise levels becomes uniform irrespective of the luminance value with respect to the noise level of the light shot noise that varies according to the luminance value of the video data. Details of the added noise will be described later.

  FIG. 1 is a block diagram illustrating a first example of a configuration of a video display system including the imaging device according to the present embodiment. The video display system 1 includes an imaging device 10 that captures an arbitrary object, and a high-speed display device (display device) 30 to which video data (video signal) output from the imaging device 10 is input in real time.

  The imaging device 10 includes an imaging device 11 and a video output unit 12. The imaging device 10 may be configured by, for example, a one-chip semiconductor device in which the imaging device 11 and the video output unit 12 are integrally configured, or the imaging device 11 and the video output unit 12 may be separately provided. For example, a configuration including a semiconductor device having a plurality of chips may be employed.

  The imaging device 11 is configured to include a solid-state imaging device such as a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. The imaging device 11 captures an image of a subject formed by an imaging lens (not shown), and acquires an imaging signal having a high frame rate of, for example, 480 fps or more, which exceeds human visual time sensitivity. Then, the imaging device 11 generates video data of the first gradation having a first bit number (for example, 8 bits) (hereinafter, also referred to as captured video data). The frame rate of the captured video data is, for example, about 1000 fps. The video data of the first gradation has a luminance value of the first gradation (for example, 8 bits). Therefore, the imaging device 11 generates and outputs a total of 24 bits of video data, for example, 8 bits for each of R, G, and B for the captured image obtained by photoelectrically converting the subject image. At this time, the imaging device 11 outputs the first gradation image data with a predetermined gain according to a gain setting value input by user setting or the like.

  The video output unit 12 encodes the video data of the first gradation and generates video data of the second gradation (hereinafter referred to as display video data) having a second bit number (for example, 4 bits) smaller than the first bit number. ) Is generated and output. That is, the video output unit 12 generates and outputs the display video data of the second gradation having a gradation value smaller than the first gradation normally obtained from the captured video data. The video output unit 12 includes a calculation unit 13, a noise generator 14, an adder 15, and a quantizer 16. Here, the operation unit 13, the noise generator 14, and the adder 15 have a function as an example of a noise adding unit, and the quantizer 16 has a function as an example of a modulation unit.

  The calculation unit 13 calculates the amplitude range of the added noise according to the brightness value based on the brightness value of the video data output from the imaging device 11. At this time, the calculation unit 13 calculates the amplitude range of the added noise according to the luminance value according to the gain setting value input by user setting or the like. The calculation unit 13 may calculate the amplitude range to which the correction value based on the temperature is added, using the temperature measurement value of the imaging device output from the imaging device 11. The noise generator 14 includes, for example, an oscillator that generates a triangular wave, or a random number generator that generates a random number, and generates an additive noise having a random value that fluctuates in the amplitude range calculated by the arithmetic unit 13. I do. The adder 15 adds the first-gradation video data of the current frame sequentially output from the imaging device 11 and the added noise output from the noise generator 14, and converts the noise-added video data into a quantizer. 16 is output.

  The quantizer 16 quantizes the video data obtained by adding noise to the video data of the first gray scale to video data of the second gray scale and sequentially outputs the data. The quantizer 16 can generate data (quantized data) in which the output of the imaging device 11 is reduced in gradation. Therefore, the imaging device 10 outputs, as the high frame rate video data obtained by the imaging, the display video data of the second gradation in which the data amount is smaller than the captured video data of the first gradation at the time of imaging.

  The high-speed display device 30 is configured to include a display device having a known configuration such as a liquid crystal display, an organic EL (ElectroLuminescence) display, and a plasma display. The high-speed display device 30 receives video data (display video data) transmitted from the imaging device 10 and can display a high-speed video having a high frame rate (for example, 480 fps or more) exceeding human visual time sensitivity. At this time, the delay from display of the display video data to transmission and display from the imaging device 10 to the high-speed display device 30 can be reduced to about 1 ms when the frame rate of the display video data is 1000 fps, for example.

  FIG. 2 is a diagram illustrating an example of a noise characteristic in the imaging device according to the present embodiment. Here, the amplitude range of the added noise in the present embodiment will be described with reference to FIG. In the imaging device 11 of the imaging apparatus 10, optical shot noise is generated as intrinsic noise, and the output imaging signal includes a component of the optical shot noise Ns. Since the light shot noise Ns is proportional to the square root of the number of photons, the noise level increases as the luminance value increases due to the luminance value of the imaging signal. Further, in the imaging device 11, a thermal noise Nt corresponding to the ambient temperature is generated. The thermal noise Nt has a substantially constant noise level regardless of the luminance value of the imaging signal.

  In the present embodiment, when random noise is intentionally added in order to recover a gradation component lost due to the reduction in the number of bits of the luminance value, the fluctuation of the light shot noise Ns due to the luminance value is taken into account, and the added noise is considered. Is set. That is, the amplitude range Na of the added noise sets an amplitude range that fluctuates according to the luminance value such that the noise level decreases as the luminance value increases. For example, when the luminance value is represented by 8 bits (0 to 255) and the 8-bit luminance value is quantized into 4 bits, random numbers having a uniform distribution in an amplitude range of 0 to 15 are added as addition noise. At this time, the amplitude range of the added noise (the range in which random numbers are generated) is changed according to the luminance value. More specifically, the addition noise generated in a wide amplitude range is added in a low luminance region, and the addition noise generated in a narrow amplitude range is added in a high luminance region. Thereby, the sum of the noise levels of the respective brightness values in the imaging device 10 is made uniform over the entire brightness value, that is, the sum of the noise levels is made uniform regardless of the brightness value, and the added noise is excessively added. Don't overdo it.

  When the frame rate of the video data is low, the addition of noise only increases flicker and noise. On the other hand, in the case of a high frame rate that exceeds the human visual time sensitivity, multiple frames appear to overlap as afterimages, so by putting the average value and fluctuation value of the added noise within a specified time with an appropriate amount, For human eyes, it is possible to visually increase the gradation in a pseudo manner without feeling flicker.

The amplitude range Na of the added noise can be represented, for example, by the following equation (1).
Na = Q2-sqrt (y) × Cg + Nt (1)
Here, Q2 is a quantization range to the second gradation, and is 16, for example, when the second bit number is 4 bits. y is a luminance value of the captured video data output from the imaging device 11, and takes a value from 0 to 255 when the first bit number is 8 bits, for example. sqrt (y) indicates the square root of the luminance value y. Therefore, sqrt (y) × Cg corresponds to the standard deviation of a value proportional to the component of the light shot noise Ns. Cg is a gain correction value, and a predetermined constant corresponding to a gain setting value of the imaging device 10 may be used. Since the number of photons corresponding to the luminance value of the output of the imaging device 11 changes according to the gain setting value, correction is performed according to the gain setting value using the gain correction value Cg. Nt is a value of thermal noise estimated in the imaging device 11. Note that a predetermined coefficient may be further added as a correction value.

  Since the sum N of the noise levels including the intrinsic noise and the added noise in the imaging device 10 is N ≒ Ns + Na + Nt, the amplitude range Na of the added noise that fluctuates according to the luminance value is set as in the above equation (1). Thus, the sum N of the noise levels can be made uniform regardless of the luminance value. The sum of the noise levels can be determined, for example, by extracting the relationship between luminance and noise by statistical analysis of video data output from the imaging device 10 and determining whether the sum is uniform regardless of the luminance value.

  FIG. 3 is a diagram illustrating an operation example of adding noise to video data in the imaging device according to the present embodiment. FIG. 3 exemplifies a case where the amplitude range of the added noise is a fixed value for the sake of simplicity. The illustrated example is an example in which the luminance value of the video data is set to each gradation value of 0 to 240, the amplitude range of the added noise is set to 16, and the added noise is set to a fluctuation value that randomly changes between 0 and 15. The adder 15 adds the luminance value of the video data output from the imaging device 11 and the addition noise output from the noise generator 14, and sequentially integrates the integrated value as the noise-added video data. 16 is output. The quantizer 16 converts the video data to which noise has been added into video data of the second gradation and sequentially outputs the data.

  FIG. 4 is a block diagram illustrating a second example of the configuration of the video display system including the imaging device according to the present embodiment. The video display system 1A includes an imaging device 20 that captures an arbitrary object, and a high-speed display device 30 to which video data output from the imaging device 20 is input in real time. The second example is another configuration example having an imaging device 20 configured by an analog circuit instead of the imaging device 10 of the first example. Here, components different from those in the first example will be described, and description of the same components will be appropriately omitted.

  The imaging device 20 includes an imaging device 21 and a video output unit 22 having an analog configuration. The imaging device 20 may be configured by, for example, a one-chip semiconductor device in which the imaging device 21 and the video output unit 22 are integrally configured, or the imaging device 21 and the video output unit 22 may be separately provided. For example, a configuration including a semiconductor device having a plurality of chips may be employed.

  The imaging device 21 acquires an imaging signal of a high frame rate and outputs it as a video signal (imaged video data) of an analog signal. The video output unit 22 modulates a video signal output from the imaging device 21, and modulates a second gray level (for example, 8 bits) smaller than a first gray level (for example, 8 bits) normally obtained from captured video data at the time of imaging. For example, 4 bit) video data (display video data) is generated and output. The video output unit 22 includes a noise generator 23, a variable amplifier (AMP) 24, an addition amplifier circuit 25, and an AD converter (ADC) 26. Here, the noise generator 23, the variable amplifier 24, and the addition amplification circuit 25 have a function as an example of a noise addition unit, and the AD converter 26 has a function as an example of a modulation unit.

  The noise generator 23 includes, for example, an oscillator that generates a triangular wave, an analog noise generation circuit, or the like, and generates and outputs random addition noise of a predetermined level. The variable amplifier 24 receives the luminance value of the video signal output from the imaging device 21 as a control input, uses the added noise generated by the noise generator 23 as a signal input, and reduces the added noise by a gain changed according to the luminance value. Amplify and output. As a result, the output of the variable amplifier 24 outputs an addition noise having an amplitude corresponding to the luminance value. The addition amplification circuit 25 receives the video signal (imaged video data) output from the imaging device 21 and the added noise output from the variable amplifier 24, adds (superimposes) the two, amplifies and outputs them. The AD converter 26 converts the analog video signal to which the noise is added, output from the addition amplification circuit 25, into digital data of a second gradation having a second bit number (for example, 4 bits), and sequentially as display video data. Output. Thereby, the imaging device 10 outputs, as high frame rate video data obtained by imaging, display video data of the second gradation in which the data amount is reduced by lowering the gradation with respect to the output of the imaging device 21. .

  Next, an operation example of the imaging device according to the present embodiment will be described. Here, an example of the gradation and noise level of the output display video data with respect to the luminance value of the captured video data is shown.

  FIG. 5 is a diagram illustrating an example of a relationship between an output luminance value of a video signal in the imaging device and a noise level, and is a diagram illustrating a virtual state in which noise does not occur. The upper part of FIG. 5 shows the statistical average value of the output of the display video data with respect to the luminance value of the captured video data, and represents the gray scale visible to human eyes. The lower part of FIG. 5 shows the statistical average value of the output of the noise level with respect to the luminance value of the captured video data. When the noise level is 0 over the entire range of the luminance value of the captured video data, the video data of the first gray scale (for example, 8 bits) is encoded into the video data of the second gray scale (for example, 4 bits), and the output display is performed. The gradation of the video data becomes coarse. In this case, human eyes perceive as a stepwise gradation change.

  FIG. 6 is a diagram illustrating an example of a relationship between an output luminance value of a video signal and a noise level in the imaging device, and is a diagram illustrating a state of an actual imaging device in which optical shot noise occurs. The upper part of FIG. 6 shows the statistical average value of the output of the display video data with respect to the luminance value of the captured video data, and the lower part of FIG. 6 shows the statistical average value of the output of the noise level with respect to the luminance value of the captured video data. Is shown. Here, for the sake of simplicity, it is assumed that the situation is very noisy, and a simulation result in which 10,000 noises of the normal distribution are generated for each of the luminance values of 0 to 255 is shown. In this case, the component of the light shot noise Ns is added to the captured video data as inherent noise that occurs naturally in the imaging device. Therefore, when the image data is encoded from the first gradation to the second gradation video data, a pseudo gradation is added to human vision by noise addition, and the gradation component lost due to the reduction in the number of bits is recovered. . Since the light shot noise Ns has a higher noise level as the luminance value of the captured video data increases, a smoother gradation change can be obtained in a higher luminance region as a human eye.

  FIG. 7 is a diagram illustrating an example of a relationship between an output luminance value of a video signal and a noise value as an operation example in the imaging apparatus of the comparative example. FIG. 7 illustrates a state where addition noise is added in a uniform range at each luminance value. FIG. The upper part of FIG. 7 shows the statistical average value of the output of the display video data with respect to the luminance value of the captured video data, and the lower part of FIG. 7 shows the statistical average value of the output of the noise level with respect to the luminance value of the captured video data. Is shown. Here, for the sake of simplicity, it is assumed that the situation is very noisy, and a simulation result in which 10,000 noises of the normal distribution are generated for each of the luminance values of 0 to 255 is shown. The comparative example is an example in which the addition noise Na is added in a uniform range from low luminance to high luminance. In this comparative example, the sum N of the noise levels increases as the luminance value increases in conjunction with the light shot noise Ns because the added noise Na is constant. In this case, the added noise is excessively added in the high luminance area, and the standard deviation of the noise level increases, so that the output fluctuates greatly and the output level may not be within the predetermined range. This causes distortion in the output video and causes flicker. Further, there may be a problem that a gradation cannot be obtained at both ends of the low-luminance region and the high-luminance region. As described above, there is a case where the dynamic range cannot be stably secured from low luminance to high luminance, and there is a possibility that the quality of the displayed image is deteriorated.

  FIG. 8 is a diagram illustrating an example of a relationship between an output luminance value of a video signal and a noise value as an operation example of the imaging apparatus according to the present embodiment, in which a range is varied according to the luminance value and additional noise is added. FIG. The upper part of FIG. 8 shows the statistical average value of the output of the display video data with respect to the luminance value of the captured video data, and the lower part of FIG. 8 shows the statistical average value of the output of the noise level with respect to the luminance value of the captured video data. Is shown. Here, for the sake of simplicity, it is assumed that the situation is very noisy. For each of the luminance values of 0 to 255, 10000 normal distribution noises are generated, and the variance is generated so that the variance is proportional to the luminance value. The results are shown. Actually, when the imaging target is bright, the S / N changes by lowering the gain setting value of the imaging device, and the noise level can be reduced. Therefore, the amplitude range of the added noise is set according to the luminance value, and the amplitude range is corrected according to the gain setting value.

  In the present embodiment, the addition noise Na is reduced with respect to the increase in the light shot noise Ns according to the luminance value and added to the captured video data so that the sum N of the noise levels becomes uniform at each luminance value. . Thus, an increase in the output deviation of the video data can be suppressed. In this way, by adding the noise Na so as to reduce the noise level in accordance with the increase in the luminance value, appropriate noise can always be added irrespective of the luminance value, and the dynamic noise can be stably controlled from low luminance to high luminance. Secure range. As a result, in human vision, a smooth gradation change can be obtained over the entire luminance value, the gradation component lost due to the reduction of the gradation value can be recovered, and the deterioration of the display image quality can be suppressed.

  As described above, the imaging devices 10 and 20 according to the present embodiment are normally obtained from the imaging devices 11 and 21 that obtain high-frame-rate imaging video data exceeding human visual time sensitivity by imaging, and the imaging video data. Video output units 12 and 22 for generating and outputting display video data of a second gradation having a gradation value smaller than the first gradation. The video output units 12 and 22 include a noise adding unit (arithmetic unit) that adds addition noise to the captured video data so that the sum of the noise levels of the respective brightness values becomes uniform over the entire brightness value of the captured video data. Unit 13, the noise generator 14, the adder 15, or the noise generator 23, the variable amplifier 24, the addition amplification circuit 25) and the video data to which the addition noise has been added is converted into display video data of the second gradation. A modulator (quantizer 16 or AD converter 26). In the present embodiment, when acquiring captured image data at a high frame rate and transmitting the acquired image data to a display device, an additional noise is added to the captured image data, and the added noise is added to the image data. The display image data of the second gradation having a small gradation value is generated and output. By such signal processing, the data amount of the video data is reduced to suppress the delay, and the grayscale component lost by the reduction of the grayscale value is recovered by the human eyes by the afterimage of a plurality of frames. . At this time, by making the sum of the noise levels of the respective luminance values uniform over the entire luminance value of the captured video data, it is possible to prevent the addition noise from being added excessively and to prevent the occurrence of flickering of the video. Quality can be suppressed. This makes it possible to suppress an increase in the amount of video transmission and the amount of calculation while suppressing a decrease in the quality of the displayed video.

  In the imaging device 10, the video output unit 12 is configured to output a second bit smaller than the first bit number based on the first-graded captured video data having the first bit number output from the imaging device 11. It generates and outputs the second gradation display video data having a number. As a result, it is possible to reduce the data amount by reducing the number of bits of the luminance value of the video data, and to suppress the delay.

  Further, in the imaging device 10, the video output unit 12 includes, as a noise addition unit, a calculation unit 13 that calculates an amplitude range of added noise according to a luminance value of the captured image data of the first gradation, and a calculated amplitude range. A noise generator 14 that outputs the random noise of the above as added noise, and an adder 15 that adds the picked-up video data and the added noise. Further, the video output unit 12 quantizes the video data obtained by adding the added noise to the captured video data of the first gray scale to the video data of the second gray scale and sequentially outputs the video data as display video data as a modulation unit. And a quantizer 16. With this configuration, noise is intentionally added to the captured video signal by the configuration that executes digital signal processing, the grayscale component lost due to the reduction of the grayscale value is restored, and the data amount of the video data is reduced. Thus, the delay can be suppressed.

  Further, in the imaging device 20, the video output unit 22 serves as a noise adding unit, and generates random noise generated by the noise generator 23 or the like in the device according to the luminance value of the captured video data output from the imaging device 21. It includes a variable amplifier 24 that amplifies to an amplitude and outputs the added noise, and an addition amplifier circuit 25 that superimposes and outputs the imaged video data output from the imaging device 21 and the added noise. The video output unit 22 serves as a modulation unit, which converts an analog video signal to which noise is added, output from the addition amplification circuit 25, into digital data of the second gradation, and sequentially outputs the digital video data as display video data. 26. With this configuration, noise is intentionally added to the captured video signal by the configuration that executes analog signal processing, the grayscale component lost due to the reduction of the grayscale value is restored, and the data amount of the video data is reduced. Thus, the delay can be suppressed.

  In addition, the imaging devices 10 and 20 acquire video data of a frame rate of 480 fps or more as captured video data of a high frame rate. As described above, when performing high-speed video display using video data of a high frame rate of 480 fps or more, it is possible to suppress an increase in the amount of video transmission and the amount of calculation while suppressing a decrease in the quality of the displayed video. It becomes possible.

  In addition, in the imaging devices 10 and 20, the noise adding units of the video output units 12 and 22 reduce and add the added noise as the luminance value of the captured video data increases, and add the inherent noise generated in the imaging devices 11 and 21. And the sum of the noise levels including the added noise is uniform over the entire luminance value of the captured video data. This makes it possible to make the sum of the noise levels of the respective luminance values uniform over the entire luminance value of the captured video data, and to prevent excessive addition of noise particularly in a high luminance region, Quality deterioration such as flickering can be suppressed.

  The video output method according to the present embodiment includes a step of acquiring captured video data having a high frame rate exceeding human visual time sensitivity captured by the imaging devices 11 and 21; and a method of obtaining each brightness over the entire brightness value of the captured video data. Adding addition noise to the captured video data so that the sum of the noise levels of the values becomes uniform, and using the video data after the addition noise is added to the first video data normally obtained from the captured video data. The method includes a step of generating display image data of the second gradation having a gradation value smaller than the gradation and a step of outputting the display image data of the second gradation to the high-speed display device 30. As a result, when acquiring a video having a relatively high frame rate and transmitting it to the display device, it is possible to suppress an increase in the amount of video transmission and the amount of calculation while suppressing a decrease in the quality of the displayed video. become.

  Although various embodiments have been described with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can conceive various changes or modifications within the scope of the claims, and these naturally belong to the technical scope of the present invention. I understand. Further, each component in the above embodiment may be arbitrarily combined without departing from the spirit of the invention.

  According to the present disclosure, when acquiring a video having a relatively high frame rate and transmitting the acquired video to a display device, it is possible to suppress an increase in a transmission amount and a calculation amount of the video while suppressing a decrease in quality of the displayed video. It is useful as a possible imaging device and a video output method.

DESCRIPTION OF SYMBOLS 1, 1A Video display system 10, 20 Imaging device 11, 21 Imaging device 12, 22 Video output unit 13 Operation unit 14 Noise generator 15 Adder 16 Quantizer 23 Noise generator 24 Variable amplifier 25 Addition amplification circuit 26 AD converter 30 High-speed display device

Claims (7)

An imaging device that acquires high-frame-rate captured video data that exceeds human visual time sensitivity by imaging,
And a video output unit that generates and outputs display video data of a second gradation having a gradation value smaller than the first gradation normally obtained from the captured video data,
The video output unit,
A noise adding unit that adds addition noise to the captured video data so that the sum of noise levels of the respective brightness values is uniform over the entire brightness value of the captured video data;
A modulating unit that converts the video data after the addition noise is added to the display video data of the second gradation.
Imaging device. The imaging device according to claim 1,
The video output unit,
The second gradation display video having a second bit number smaller than the first bit number based on the first gradation image video data having the first bit number output from the imaging device. Generate and output data,
Imaging device. The imaging device according to claim 2,
The noise adding unit calculates an amplitude range of the added noise according to a luminance value of the captured image data of the first gradation, and outputs a random noise of the calculated amplitude range as the added noise. A noise generator, and an adder that adds the captured video data and the added noise,
The quantization unit quantizes video data obtained by adding the addition noise to the first grayscale imaged video data to the second grayscale video data and sequentially outputs the video data as the display video data. Including vessels,
Imaging device. The imaging device according to claim 1,
A variable amplifier that amplifies random noise generated in the apparatus to an amplitude corresponding to a luminance value of captured video data output from the imaging device, and outputs the amplified noise as the added noise; Including an addition amplification circuit that outputs the captured image data and the addition noise that are output from the superimposition,
The modulation unit includes an AD converter that converts an analog video signal to which noise is added, output from the addition amplification circuit, to digital data of the second gradation and sequentially outputs the digital video data as the display video data.
Imaging device. The imaging device according to claim 1, wherein:
Acquiring video data having a frame rate of 480 fps or more as the image data of the high frame rate;
Imaging device. The imaging device according to claim 1, wherein:
The noise adding unit reduces and adds the additive noise as the luminance value increases according to a luminance value of the captured video data, and includes a noise including an intrinsic noise generated in the imaging device and the additive noise. The sum of the levels is uniform over the entire luminance value of the captured video data,
Imaging device. Acquiring high-frame-rate captured video data exceeding the human visual time sensitivity captured by the imaging device;
Adding an additional noise to the captured video data so that the sum of the noise levels of the respective brightness values becomes uniform over the entire brightness value of the captured video data;
Using the video data to which the added noise has been added, generating display video data of a second gradation having a gradation value smaller than a first gradation normally obtained from the captured video data;
Outputting the display image data of the second gradation to a display device;
An image output method having the following.