JP7149514B2 - Imaging device and video output method - Google Patents

Description

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

The video display system, which performs image processing and transmission on the video signal of moving images and displays the video on the display device, is designed to operate at a frame rate of 60 fps (frame per second) or less in consideration of human vision. It is common to be In such a video display system, a certain amount of delay occurs in the entire system due to the 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 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 can adversely affect the operation of the system. For example, when controlling a robot arm to grab an object that moves irregularly while watching an image from a distance, the image display delay can be a factor that hinders stable operation. desired. Elimination of delay in image display is also beneficial in image display systems used for endoscopic surgery and remote surgery using real-time images, remote operation of disaster relief robots, and the like.

On the other hand, by applying a relatively high frame rate (for example, 480 fps) to the video, it is also possible to suppress the delay of video display, but if the frame rate is simply increased, the amount of transmission and calculation This will lead to an increase in volume.

As a technology for suppressing the transmission volume while maintaining the high resolution of the video, for example, regarding the video captured by the surveillance camera, we focus on the vicinity of the door where people enter and exit, and we want to monitor this attention monitoring area at a high level. It is known to display at a frame rate and transmit the background of the attention monitoring area such as the place where the plant is placed or the wall at a low frame rate in consideration of the effective use of the network bandwidth. there is

JP 2008-219484 A

In the conventional technology 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 in order to maintain the high resolution of the video, even if the application of the high frame rate is part of the image such as the attention monitoring area, , the increased transmission and computational complexity can be a problem.

The present disclosure can suppress an increase in the amount of video transmission and the amount of calculation while suppressing deterioration in the quality of the displayed video when acquiring video with a relatively high frame rate and transmitting it to the display device. It is an object of the present invention to provide an imaging device and a video output method capable of capturing images.

The present disclosure includes an imaging device that acquires imaged video data by imaging , and display image data of a second gradation whose gradation value is smaller than the first gradation obtained from the imaged video data. and a video output unit for outputting, the video output unit outputs to the captured video data such that the sum of noise levels of each luminance value is uniform over the entire luminance value of the captured video data. and a modulation unit for converting video data to which the additive noise has been added into display video data of the second gradation.

Further, the present disclosure includes a step of acquiring imaged video data by an imaging device, and performing the imaged image data so that the sum of noise levels of each luminance value is uniform over the entire luminance value of the imaged image data. a step of adding additive noise to video data; and a second gradation having a smaller gradation value than the first gradation obtained from the captured video data using the video data to which the additive noise has been added. and outputting the display image data of the second gradation to a display device.

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

1 is a block diagram showing a first example of a configuration of a video display system including an imaging device according to this embodiment; FIG. FIG. 4 is a diagram showing an example of noise characteristics in the imaging device according to this 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 a video display system including an imaging device according to this embodiment; FIG. 3 is a diagram showing an example of the relationship between the output luminance value of a video signal and the noise level in an imaging device, and is a diagram showing a virtual state in which noise does not occur; FIG. 3 is a diagram showing an example of the relationship between the output luminance value of a video signal and the noise level in an imaging device, and is a diagram showing the state of an actual imaging device in which optical shot noise occurs; FIG. 11 is a diagram showing an operation example of an imaging device of a comparative example; 4A and 4B are diagrams showing operation examples of the imaging device according to the present embodiment;

Hereinafter, each embodiment specifically disclosing the configuration according to the present disclosure will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary verbosity in the following description and to facilitate understanding by those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for a thorough understanding of the present disclosure by those skilled in the art and are not intended to limit the claimed subject matter.

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

Here, the temporal characteristics of the contrast sensitivity function (CSF) of the visual system will be described. Regarding the temporal frequency of CSF, the temporal frequency at which flicker is no longer perceived when the stimulus is contrast-inverted is called the critical flicker frequency (CFF), and CFF is the maximum detectable stimulus under constant contrast. Corresponds to time frequency. The human CFF is about 50 Hz, and 60 to 120 Hz at the fastest is considered to be the limit for detecting changes in contrast. This upper limit of human perceptibility is referred to herein as human visual temporal sensitivity (temporal resolution of visual information processing). A high-speed video with a frame rate of 480 fps or more, which exceeds human visual time sensitivity, causes humans to perceive the video as an afterimage across a plurality of frames.

Considering such characteristics of human vision, in the present embodiment, random noise is added to video data captured by an imaging device at a relatively high frame rate to reduce the number of bits of luminance values. Transmits with reduced gradation. In this case, while reducing the gradation value of the video data, so-called dither processing is performed by adding random noise to output the data. As a result, the data amount of the video data is reduced, and the gradation components lost due to the reduction of the gradation value are restored by the afterimage perception of multiple frames by the human eye to give a pseudo gradation, To suppress deterioration in quality of displayed video.

Stochastic resonance is known to occur by adding random noise to a signal. In the present embodiment, stochastic resonance is used to intentionally add random noise to video data so that signal components below the threshold can be detected with a certain probability. Recover lost gradation components.

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

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

The imaging apparatus 10 has an imaging device 11 and a video output section 12 . The imaging device 10 may be composed of, 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 of a plurality of chips may be used.

The imaging device 11 includes a solid-state imaging device such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. The imaging device 11 captures an image of a subject formed by an imaging lens (not shown), and acquires an imaging signal with a high frame rate of, for example, 480 fps or higher, which exceeds human visual temporal sensitivity. Then, the imaging device 11 generates first gradation video data (hereinafter also referred to as captured video data) having a first number of bits (for example, 8 bits). The frame rate of captured video data is, for example, approximately 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 24-bit video data in total of 8 bits for each color of R, G, and B, for example, for the captured image obtained by photoelectrically converting the subject image. At this time, the imaging device 11 outputs video data of the first gradation with a predetermined gain according to the gain setting value input by user setting or the like.

The video output unit 12 encodes the first gradation video data to generate second gradation video data (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 image output unit 12 generates and outputs display image data of the second gradation whose gradation value is smaller than the first gradation normally obtained from the imaged image data. The video output unit 12 has an arithmetic unit 13 , a noise generator 14 , an adder 15 and a quantizer 16 . Here, the calculator 13, the noise generator 14, and the adder 15 function as an example of the noise adder, and the quantizer 16 functions as an example of the modulator.

Based on the luminance value of the video data output from the imaging device 11, the calculation unit 13 calculates the amplitude range of the added noise according to the luminance value. 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. Note that the calculation unit 13 may use the temperature measurement value of the imaging device output from the imaging device 11 to calculate the amplitude range to which the correction value due to the temperature is added. The noise generator 14 includes, for example, an oscillator that generates a triangular wave or a random number generator that generates random numbers, and generates additive noise having random values that fluctuate within the amplitude range calculated by the calculator 13. do. The adder 15 adds the video data of the first gradation for the current frame sequentially output from the imaging device 11 and the addition noise output from the noise generator 14, and quantizes the video data after noise addition. 16.

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

The high-speed display device 30 includes a display device having a known configuration such as a liquid crystal display, an organic EL (ElectroLuminescence) display, a plasma display, or the like. The high-speed display device 30 receives video data (display video data) transmitted from the imaging device 10, and is capable of displaying high-speed video at a high frame rate (for example, 480 fps or higher) that exceeds human visual time sensitivity. At this time, the delay from the imaging device 10 to the display video data transmitted to the high-speed display device 30 for display 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 showing an example of noise characteristics in the imaging device according to this embodiment. Here, with reference to FIG. 2, the amplitude range of additive noise in this embodiment will be described. In the imaging device 11 of the imaging apparatus 10, light shot noise is generated as inherent noise, and the output imaging signal contains the component of the light 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 brightness value of the imaging signal increases. Also, thermal noise Nt is generated in the imaging device 11 according to the ambient temperature. The thermal noise Nt has a substantially constant noise level regardless of the luminance value of the imaging signal.

In this embodiment, when intentionally adding random noise in order to recover gradation components lost by reducing the number of bits of the luminance value, the addition noise set the amplitude range Na of That is, the amplitude range Na of the additive noise is set to vary according to the luminance value so 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 to 4 bits, a random number with a uniform distribution in the amplitude range of 0 to 15 is added as addition noise. At this time, the amplitude range of the additive noise (random number generation range) is changed according to the luminance value. More specifically, additive noise generated in a wide amplitude range is added to the low luminance region, and additive noise generated in a narrow amplitude range is added to the high luminance region. As a result, the total noise level of each luminance value in the imaging device 10 is made uniform over the entire luminance value, that is, the total noise level is made uniform regardless of the luminance value, and the addition noise is excessively added. Don't overdo it.

When the frame rate of video data is low, adding noise only increases flicker and noise. On the other hand, in the case of a high frame rate that exceeds the temporal sensitivity of human vision, multiple frames appear to overlap as afterimages. For human vision, it is possible to visually increase the gradation in a pseudo manner without perceiving flickering.

The amplitude range Na of the additive noise can be expressed, for example, by the following equation (1).
Na=Q2-sqrt(y)×Cg+Nt (1)
Here, Q2 is the quantization range to the second gradation, and is 16 when the second number of bits is 4 bits, for example. y is the luminance value of the captured video data output from the imaging device 11, and is any 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 values proportional to the components of optical shot noise Ns. Cg is a gain correction value, and a predetermined constant corresponding to the 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 depending on the gain setting value, correction according to the gain setting value is performed using the gain correction value Cg. Nt is the value of thermal noise estimated in the imaging device 11 . A predetermined coefficient may be added as the correction value.

Since the sum N of the noise levels including the inherent noise and the additive noise in the imaging device 10 is N≈Ns+Na+Nt, the amplitude range Na of the additive noise that varies according to the luminance value is set as in the above equation (1). As a result, the total noise level N can be made uniform regardless of the luminance value. For example, it is possible to determine whether or not the total noise level is uniform regardless of the luminance value by extracting the relationship between luminance and noise through statistical analysis of video data output from the imaging device 10 .

FIG. 3 is a diagram showing an operation example of adding noise to video data in the imaging device according to the present embodiment. In order to simplify the explanation, FIG. 3 illustrates a case in which the amplitude range of added noise is a fixed value. In the illustrated example, the luminance value of video data is set to each gradation value of 0 to 240, the amplitude range of additive noise is set to 16, and the additive noise is set to a variable value that varies randomly between 0 and 15. FIG. The adder 15 adds the luminance value of the video data output from the imaging device 11 and the added noise output from the noise generator 14, and sequentially integrates the integrated values as video data after adding noise to the quantizer. 16. The quantizer 16 converts the noise-added video data into video data of the second gradation and sequentially outputs the video data.

FIG. 4 is a block diagram showing a second example of the configuration of the image display system including the imaging device according to this embodiment. The image display system 1A has an imaging device 20 that images an arbitrary object, and a high-speed display device 30 that receives video data output from the imaging device 20 in real time. A 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 descriptions of the same configurations will be omitted as appropriate.

The imaging apparatus 20 has an imaging device 21 and an analog video output section 22 . The imaging device 20 may be composed of, 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 of a plurality of chips may be used.

The imaging device 21 acquires a high frame rate imaging signal and outputs it as an analog video signal (captured video data). The video output unit 22 modulates the video signal output from the imaging device 21 to convert it to a second gradation (e.g., 8 bits) having a smaller gradation value than the first gradation (e.g., 8 bits) normally obtained from the 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 has 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, variable amplifier 24, and addition amplifier circuit 25 function as an example of a noise addition section, and the AD converter 26 functions as an example of a modulation section.

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, receives the added noise generated by the noise generator 23 as a signal input, and converts the added noise by a gain that is changed according to the luminance value. Amplify and output. As a result, the output of the variable amplifier 24 is added noise having an amplitude corresponding to the luminance value. The summing amplifier circuit 25 receives the video signal (captured video data) output from the imaging device 21 and the summing noise output from the variable amplifier 24, adds (superimposes) them, amplifies them, and outputs them. The AD converter 26 converts the noise-added analog video signal output from the addition amplifier circuit 25 into digital data of a second gradation having a second number of bits (for example, 4 bits), and sequentially converts it into display video data. Output. As a result, the imaging device 10 outputs display video data of the second gradation, which is obtained by lowering the gradation of the output of the imaging device 21 to reduce the amount of data, as high-frame-rate video data obtained by imaging. .

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

FIG. 5 is a diagram showing an example of the relationship between the output luminance value of the video signal and the noise level in the imaging device, and is a diagram showing a virtual state in which no noise occurs. The upper part of FIG. 5 shows the statistical average value of the output of the display image data with respect to the luminance value of the captured image data, representing the gradation visible to the human eye. The lower part of FIG. 5 shows the statistical average value of the noise level output with respect to the luminance value of the imaged video data. When the noise level is 0 over the entire luminance value range of the imaged video data, encoding the video data of the first gradation (e.g. 8 bits) into the video data of the second gradation (e.g. 4 bits) results in an output display The gradation of video data becomes rough. In this case, the human eye perceives it as a step-like gradation change.

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

FIG. 7 is a diagram showing an example of the relationship between the output luminance value of the video signal and the noise value as an operation example of the imaging apparatus of the comparative example, and shows a state in which additive noise is added in a uniform range to each luminance value. Fig. 3 shows. 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 noise level output with respect to the luminance value of the captured video data. is shown. Here, for the sake of clarity, a very noisy situation is assumed, and simulation results are shown in which 10,000 pieces of normal distribution noise are generated for each luminance value of 0 to 255. FIG. A comparative example is an example in which additive noise Na is added in a uniform range from low luminance to high luminance. In this comparative example, since the added noise Na is constant, the total noise level N increases as the luminance value increases in conjunction with the light shot noise Ns. In this case, the additive noise is excessively added in the high-luminance region, and the standard deviation of the noise level increases. This causes distortion in the output image and causes flickering. In addition, there may arise a problem that gradation cannot be obtained at both ends of the low-luminance region and the high-luminance region. In this way, it may not be possible to ensure a stable dynamic range from low luminance to high luminance, which may lead to deterioration in the quality of the displayed image.

FIG. 8 is a diagram showing an example of the relationship between the output luminance value of the video signal and the noise value, as an operation example of the imaging apparatus of the present embodiment. It is the figure which showed the state which carried out. 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 noise level output with respect to the luminance value of the captured video data. is shown. Here, to make it easier to understand, we assumed a very noisy situation, and generated 10,000 pieces of normally distributed noise for each luminance value from 0 to 255, and generated a simulation in which the variance was proportional to the luminance value. shows the results. Actually, when the object to be imaged is bright, the S/N is changed by lowering the gain setting value of the imaging device, and the noise level can be lowered. Therefore, the amplitude range of the additive noise is set according to the luminance value, and the amplitude range is corrected according to the gain setting value.

In this embodiment, the addition noise Na is reduced with respect to the increase in the light shot noise Ns according to the luminance value so that the sum N of noise levels is uniform at each luminance value, and added to the captured image data. . As a result, it is possible to suppress an increase in the output deviation of the video data. In this way, by varying the added noise Na so that the noise level decreases as the luminance value increases, it is possible to always add appropriate noise regardless of the luminance value. Ensure range. As a result, a smooth gradation change can be obtained for the entire luminance value in human vision, the gradation component lost due to the reduction of the gradation value can be recovered, and the deterioration of the quality of the displayed image can be suppressed.

As described above, the image capturing apparatuses 10 and 20 of the present embodiment include the image capturing devices 11 and 21 that acquire captured video data with a high frame rate that exceeds human visual time sensitivity, and and image output units 12 and 22 for generating and outputting display image data of a second gradation whose gradation value is smaller than that of the first gradation. The video output units 12 and 22 each include a noise addition unit (computation unit) that adds addition noise to the captured video data so that the sum of the noise levels of each luminance value is uniform over the entire brightness value of the captured video data. section 13, noise generator 14, adder 15, or noise generator 23, variable amplifier 24, addition amplifier circuit 25), and converts the video data to which the addition noise has been added into display video data of the second gradation. and a modulator (quantizer 16 or AD converter 26). In the present embodiment, when captured video data with a high frame rate is acquired and transmitted to a display device, additive noise is added to the captured video data to obtain a higher gradation than the first gradation normally obtained from the captured video data. Display image data of a second gradation with a smaller gradation value is generated and output. Through such signal processing, the amount of video data is reduced to suppress delays, and the gradation components lost due to the reduction in gradation values are restored by the afterimage-like perception of multiple frames by the human eye. . At this time, by making the sum of the noise levels of each luminance value uniform over the entire luminance value of the imaged video data, it is possible to prevent excessive addition of additive noise and prevent flickering of the image. quality deterioration can be suppressed. This makes it possible to suppress an increase in the amount of video transmission and the amount of calculation while suppressing deterioration in the quality of the displayed video.

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

In the image pickup apparatus 10, the image output unit 12 includes, as a noise addition unit, a calculation unit 13 that calculates the amplitude range of added noise according to the luminance value of the imaged image data of the first gradation, and the calculated amplitude range A noise generator 14 for outputting random noise as additive noise, and an adder 15 for adding the captured video data and the additive noise. Further, the image output unit 12, as a modulation unit, quantizes image data obtained by adding addition noise to captured image data of the first gradation into image data of the second gradation, and sequentially outputs the quantized image data as display image data. It includes a quantizer 16 that As a result, by using a configuration that executes digital signal processing, noise is intentionally added to the imaged video signal to restore the gradation components that were lost due to the reduction in the gradation value, and to reduce the data volume of the video data. delay can be suppressed.

In the imaging device 20, the video output unit 22, as a noise addition unit, adds 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 the amplitude and outputs it as additive noise, and an additive amplifier circuit 25 that superimposes the captured image data output from the imaging device 21 and the additive noise and outputs the additive noise. The video output unit 22, as a modulation unit, converts the noise-added analog video signal output from the addition amplifier circuit 25 into digital data of the second gradation, and sequentially outputs the data as display video data. 26. As a result, by using a configuration that executes analog signal processing, noise is intentionally added to the imaged video signal to restore the gradation components that were lost due to the reduction in the gradation value, and to reduce the data volume of the video data. delay can be suppressed.

In addition, in the imaging devices 10 and 20, video data with a frame rate of 480 fps or more is acquired as the captured video data with a high frame rate. In this way, when high-speed video display is performed using video data with 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 deterioration in the quality of the displayed video. It becomes possible.

In addition, in the imaging devices 10 and 20, the noise addition units of the video output units 12 and 22 decrease and add the added noise as the luminance value of the captured video data increases, and the unique noise generated in the imaging devices 11 and 21 The sum of the noise levels including the noise and the additive noise is uniform over the entire luminance value of the imaged video data. As a result, the sum of the noise levels of each luminance value can be made uniform over the entire luminance value of the imaged video data, and it is possible to prevent excessive addition of noise particularly in a high luminance region, thereby improving the image quality. Quality deterioration such as flickering can be suppressed.

The image output method of the present embodiment comprises steps of obtaining imaged image data having a high frame rate exceeding human visual temporal sensitivity captured by the imaging devices 11 and 21, and obtaining each luminance value over the entire luminance value of the imaged image data. A step of adding additive noise to the captured video data so that the sum of the noise levels of the values is uniform; A step of generating display image data of a second gradation whose gradation value is smaller than the gradation, and a step of outputting the display image data of the second gradation to the high-speed display device 30 are provided. As a result, when an image with a relatively high frame rate is acquired and transmitted to the display device, it is possible to suppress an increase in the amount of image transmission and the amount of calculation while suppressing deterioration in the quality of the displayed image. become.

Various embodiments have been described above with reference to the drawings, but it goes without saying that the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present invention. Understood. Moreover, each component in the above embodiments may be combined arbitrarily without departing from the spirit of the invention.

The present disclosure can suppress an increase in the amount of video transmission and the amount of calculation while suppressing deterioration in the quality of the displayed video when acquiring video with a relatively high frame rate and transmitting it to the display device. It is useful as an imaging device and a video output method that can be used.

Reference Signs List 1, 1A video display system 10, 20 imaging device 11, 21 imaging device 12, 22 video output unit 13 arithmetic unit 14 noise generator 15 adder 16 quantizer 23 noise generator 24 variable amplifier 25 addition amplifier circuit 26 AD converter 30 high speed display

Claims (8)

an imaging device that acquires imaged video data by imaging;
a video output unit that generates and outputs display video data of a second gradation having a smaller gradation value than the first gradation obtained from the captured video data,
The video output unit is
a noise addition unit that adds additive noise to the imaged video data so that the sum of noise levels of each luminance value is uniform over the entire luminance value of the imaged video data;
a modulation unit that converts the video data to which the additive noise has been added into the display video data of the second gradation;
Imaging device. The imaging device according to claim 1,
The captured video data has a high frame rate that exceeds human visual temporal sensitivity,
Imaging device. The imaging device according to claim 1,
The video output unit is
A display image of the second gradation having a second number of bits smaller than the first number of bits based on the imaged image data of the first gradation having the first number of bits output from the imaging device. generate and output data,
Imaging device. The imaging device according to claim 3,
The noise addition unit includes a calculation unit that calculates an amplitude range of the added noise corresponding to the luminance value of the captured video data of the first gradation, and outputs random noise in the calculated amplitude range as the added noise. and an adder that adds the captured video data and the added noise,
The modulation unit quantizes the video data obtained by adding the additive noise to the imaged video data of the first gradation into the video data of the second gradation and sequentially outputs the video data as the display video data. including vessel
Imaging device. The imaging device according to claim 1,
The noise addition unit amplifies random noise generated in the apparatus to an amplitude corresponding to the luminance value of captured video data output from the imaging device, and outputs the added noise as the variable amplifier; and the imaging device. a summing amplifier circuit that superimposes and outputs the captured video data output from and the summing noise,
The modulation unit includes an AD converter that converts the noise-added analog video signal output from the addition amplifier circuit into digital data of the second gradation and sequentially outputs the digital data as the display video data.
Imaging device. The imaging device according to claim 2,
Acquiring video data with a frame rate of 480 fps or higher as the captured video data with a high frame rate;
Imaging device. The imaging device according to any one of claims 1 to 6,
The noise addition unit reduces and adds the added noise as the brightness value increases according to the brightness value of the imaged video data, and adds noise including inherent noise generated in the imaging device and the added noise. The sum of levels is uniform over the entire brightness value of the captured video data,
Imaging device. acquiring imaged video data by an imaging device;
a step of adding additive noise to the imaged video data so that the sum of noise levels of each luminance value is uniform over the entire luminance value of the imaged video data;
a step of generating display video data of a second gradation having a smaller gradation value than the first gradation obtained from the captured video data, using the video data to which the additive noise has been added;
a step of outputting the display video data of the second gradation to a display device;
A video output method having

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