JP2005109717A - Apparatus and method of processing video data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To utilize gradation reproduction characteristics of a display device to the maximum. <P>SOLUTION: A video data processing apparatus is provided which has a detecting means (41) for detecting the maximum value and the minimum value of the pixel value of video data, a first converting means (41) for applying data conversion to the pixel value of the video data between the maximum and minimum values into the transmittable maximum gradation, transmitting means (42, 43) for transmitting the converted video data and transmitting information capable of reproducing the maximum and minimum values, a receiving means (51) for receiving the video data and information transmitted by the transmitting means, and a second converting means (52, 53) for performing gradation conversion into display data to be displayed on the display device on the basis of the video data and information which are received. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a video data processing technique, and more particularly to a processing technique for communicating video data.

  When the digital receiver IRD (Integrated Receiver Decoder) for digital broadcast reception and the display / playback unit are separated and transmitted as digital video signals, for example, in the TMDS or GVIF format commonly used in the transmission unit, RGB (red, green, blue) Each 8bits transmission. On the other hand, the number of gradations that can be processed by the IRD unit and that can be displayed by the display / playback unit exceeds the number of gradations that can be transmitted. -The display processing gradation was the same as the transmission gradation.

  Even if the number of gradations that can be processed by the IRD unit and the display / playback unit exceeds the number of gradations that can be transmitted, the number of display gradations is limited by the number of gradations of the transmission unit, thereby maximizing the capacity of the display. There are disadvantages that cannot be used. For this reason, for example, when the screen to be displayed is entirely dark, the number of transmission gradations is not sufficient, and the gradation reproducibility of the display screen becomes low, so it may not be clear what is being reflected.

  Patent Document 1 below describes a color image processing apparatus that enables color reproduction faithful to an original image during image formation.

Japanese Patent Laid-Open No. 7-23241

  An object of the present invention is to maximize the gradation reproducibility of a display device.

The video data processing apparatus according to the present invention includes a detecting means for detecting a maximum value and a minimum value of pixel values of the video data, and a pixel value of the video data between the maximum value and the minimum value is transmitted to a maximum gradation that can be transmitted. First converting means for converting; transmitting means for transmitting the converted video data and transmitting information capable of reproducing the maximum value and minimum value; and receiving the video data and information transmitted by the transmitting means Receiving means, and second conversion means for converting the gradation into display data to be displayed on the display device based on the received video data and information.
Also, the video data processing apparatus of the present invention includes a detecting means for detecting the maximum value and the minimum value of the pixel value of the video data, and a maximum gradation capable of transmitting the pixel value of the video data between the maximum value and the minimum value. Conversion means for data conversion, and transmission means for transmitting the converted video data and transmitting information capable of reproducing the maximum value and the minimum value.
Also, the video data processing apparatus of the present invention receives video data and receives information capable of reproducing the maximum and minimum pixel values of the video data, and based on the received video data and information. Conversion means for converting gradation into display data to be displayed on the display device.
Also, the video data processing apparatus of the present invention includes a transmitting means for expressing and transmitting data by changing the active width without changing the period of the synchronizing signal, and an active width of the synchronizing signal by receiving the transmitted synchronizing signal. And detecting means for detecting data from the change of.
The video data processing method of the present invention includes a detection step for detecting a maximum value and a minimum value of a pixel value of video data, and a maximum gradation capable of transmitting a pixel value of the video data between the maximum value and the minimum value. A data conversion step, and a transmission step of transmitting the converted video data and transmitting information capable of reproducing the maximum value and the minimum value.
Also, the video data processing method of the present invention is based on the reception step of receiving video data and receiving information capable of reproducing the maximum and minimum pixel values of the video data, and the received video data and information. A conversion step for converting the gradation of the display data to be displayed on the display device.
The video data processing method of the present invention includes a transmission step of expressing and transmitting data by a change in active width without changing a period of the synchronization signal, and an active width of the synchronization signal by receiving the transmitted synchronization signal. A detecting step for detecting data from the change in.

  Since the tone conversion of the video data can be performed based on the maximum value and the minimum value of the pixel value of the video data, the video data can be displayed with a tone value suitable for the display device. Even when the number of communication gradations is smaller than the number of gradations of the display device, high-quality display can be performed using the number of gradations of the display device without being limited to the number of communication gradations.

(First embodiment)
FIG. 3 shows the overall configuration of the system according to the first embodiment of the present invention. Reference numeral 10 denotes an IRD (Integrated Receiver Decoder) for receiving digital broadcasts, and 21 denotes a display / playback unit that displays and plays back video / audio signals from the IRD 10. Here, it is assumed that broadcasting is transmitted according to a DVB (Digital Video Broadcasting) broadcasting system, video is transmitted according to ISO / IEC 61818-2 MPEG2, and audio is transmitted according to ISO / IEC 61818-3 MPEG2. A CPU 17 controls the entire IRD according to the program, 18 is a memory in which the program is stored, and 19 is a common bus that connects the CPU 17 and each part. A signal from the tuner 11 that receives a digital broadcast wave and selects a desired frequency in accordance with an instruction from the CPU 17 passes through the demodulation circuit 12 and is demodulated and error-corrected. Next, a stream having a desired PID is selected from the multiplexed streams sent to the demultiplexer 13, and the video / audio stream is sent to the AV decoder 14, where it is decoded into uncompressed video / audio data, Digital input video 151 and input audio 152 are obtained. The input video 151 includes a luminance / color difference signal, a synchronization signal, and the like. These signals are converted into rgb (red, green, blue) signals by the color conversion circuit 15 and further sent to the video transmission unit 161 for processing. The input voice 152 is sent to the voice transmitter 162.

  The video signal to the display / playback unit 21 is received and processed by the video receiving unit 221 and processed by the drive unit 23 that drives the signal that can be displayed on the display 24. The audio signal is processed by an amplifier (AMP) 25 that amplifies the audio signal received by the audio receiving unit 222 and a speaker 26 that converts this into sound.

  The flow of the video signal will be described with reference to FIG. 4 which is a detailed block diagram from the color conversion circuit 15 and the video transmission unit 161 to the video reception unit 221 and FIG. 5 which is a timing diagram. The broadcast wave is a video signal that transmits luminance and color difference data in a progressive manner. The input video 151 from the broadcast wave AV decoder 14 is 8-bit luminance data Y, color difference data Cb, Cr, a vertical synchronization signal vsync, a horizontal synchronization signal hsync, a clock clk, and a data enable signal de. The color conversion circuit 15 calculates and outputs red, green, and blue rgb data from these luminance / color difference data using the inverse transformation of the following equation.

Y = 0.587g + 0.114b + 0.299r (1)
Cb = 0.564 (bY)
Cr = 0.713 (rY)

  Since the coefficient of the formula is 3 digits after the decimal point, the calculation result rgb data is assumed to have an accuracy of 10 bits each.

  The video transmission unit 161 includes three blocks (A) to (C).

(A) The “maximum / minimum detection and RGB conversion circuit 41” performs the following processing for each period of the vertical synchronization signal vsync, that is, for each screen.

(1) Detection of maximum and minimum pixel values for each screen
The maximum brightness value is detected for each of the red, green, and blue colors of all pixels in one screen and set as maxr, maxg, and maxb, respectively. Further, the largest value among them is defined as max.
Similarly, the minimum value of brightness is detected for each pixel of red, green, and blue in one screen, and is set to minr, ming, and minb, respectively, and the smallest value among these is set to min.
max and min are rounded to 6bits by the following formula and the values are output as maxt and mint.
maxt = INT [max / 16 + 0.5] (2)
mint = INT [min / 16 + 0.5]
Here, INT [X] indicates that X is rounded down to an integer.

(2) RGB conversion Each 10-bit data of rgb input is allocated to 256 gradations, that is, 8 bits, between the maximum value max and minimum value min obtained earlier, and the R calculated by this formula is transmitted. Data.
R = INT [255 * (r-min) / (max-min) +0.5] (3)
G and B are also similar to the transmission data.

(B) The horizontal synchronization width modulation circuit 42 performs the following processing.
As shown in FIG. 5A, the period during which the vertical synchronization signal VSYNC is active is set to two periods of the horizontal synchronization signal HSYNC. The horizontal synchronization period is hlt as shown in FIG. 5 bb), and the high active period is usually hht. Based on the maximum / minimum values maxt and mint from the “maximum / minimum detection and RGB conversion circuit 41”, when the vertical synchronization signal is active (high period in this example), the width of the first and second horizontal synchronization signals is It shows maxt and mint by changing. Specifically, maxt is expressed by increasing the first horizontal synchronization width by maxc by the maximum value maxt of CLK. In other words, the width of the first horizontal sync signal is hht + maxc. Similarly, the minimum value mint increases the second horizontal synchronization width by minc, and the width becomes hht + minc. It is assumed that maxt and mint are 6 bits, that is, a maximum of 64, but the inactive width (hlt-hht) of the horizontal synchronization signal is sufficiently larger than 64. When the vertical synchronization signal is high, the horizontal synchronization width modulation circuit 42 performs output for changing the width of the horizontal synchronization signal so as to indicate the maximum and minimum values of the pixels.

(C) The TMDS transmission IC 43 performs the following processing.
Each 8-bit video data that has undergone RGB conversion and a video signal of a vertical / horizontal synchronization signal, a clock signal, and a data enable signal that have undergone synchronization width modulation are input to the TMDS transmission IC 43 and extracted as a TMDS output.

  The video receiving unit 221 includes three blocks (D) to (F).

(D) The TMDS receiving IC 51 performs the following processing.
The TMDS signal from the video transmission unit 161 is input to the TMDS reception IC 51, and RGB 8-bit transmission data, vertical / horizontal synchronization signals, clock signals, and data enable signal video signals are extracted.

(E) The maximum / minimum value detection circuit 52 performs the following processing in the vertical synchronization cycle.
From the vertical / horizontal synchronization signal, the clock signal, and the data enable signal, the normal active width hht when the horizontal synchronization signal is high when the vertical synchronization signal is low is known. When the vertical synchronization signal is high, the first and second horizontal synchronization widths are counted in units of clocks, and the active width hht is subtracted. Then, maxc and minc are calculated, and the maximum value maxt and the minimum value mint of the pixel can be detected and output.

(F) The rgb conversion circuit 53 performs the following processing.
The display data rr, gg, and bb of 10 bits each of red, green, and blue are reproduced from the transmission data of RGB each 8 bits, the maximum value maxt and the minimum value mint of 6 bits pixels. Red rr is calculated by the following formula.
rr = 16mint + (maxt-mint) R / 16 (4)
Green gg and blue bb are calculated using the same formula. These values are the display image 231.

  The figure that best represents the present embodiment together with the above is a diagram showing the transition of the red color space in FIG. a) is the effective color range from min to max in 1024 gradations in the space before processing the input video 151, and there is no valid color in the range from 0 to min and max to 1023, so this range is transmitted. It will be useless. In b), the transmission gradation of 8 bits, that is, all 256 gradations are valid values within the range transmitted from the video transmission unit 161, and the maximum value maxt and the minimum value mint are also transmitted. c) is a display color space of the video signal 231 and shows that between MIN and MAX values is reproduced with 256 gradations and color reproducibility is good. Here, maxt and mint are lower than the gradation of 6bits and video data in equation (2). When the gradation of these values is increased, the difference in the pixel data for each screen changes the maximum and minimum values. This is to prevent the display color from being different and difficult to see even on the same screen when reproducing the display video 231 displayed on the video receiver 221.

  FIG. 2 shows the red space before processing of the input video 151 on the horizontal axis and the space for transmission on the vertical axis. The straight line indicated by a) is the inclination of the present embodiment, and the straight line b) is a conventional example. In a), min-max values before processing are mapped up to 256 gradations in the transmission space, while in b) 1024 gradations before processing are mapped up to 256 gradations in the transmission space and are wasted Is shown to occur.

  Let's actually examine the explanation so far. For example, r = 40 when max = 600 and min = 20 in a red space. Then, maxt = 38, mint = 1 from equation (2), and transmission data R = 9 from equation (3). From the expression (4), the display data is rr = 36. In this embodiment, input values 20 to 600 of the video signal 151 are displayed in 256 gradations after transmission and processing. However, conventionally, the input values 20 to 600 are only displayed in 145 stages.

(Second Embodiment)
In the first embodiment, the maximum value and the minimum value of brightness are transmitted from the video transmission unit 161 to the video reception unit 221 by changing the width of the horizontal synchronization signal. In the second embodiment, the maximum value And the minimum value] and the minimum value may be transmitted.

At that time, the following partial changes are necessary with respect to the configuration described in the first embodiment.
The horizontal synchronizing width modulation circuit 42 represents the difference by increasing the first horizontal synchronizing width by (maxc-minc) when the vertical synchronizing signal is in the high period. In other words, the width of the first horizontal sync signal is (hht + maxc-minc). Similarly, the minimum value mint increases the second horizontal synchronization width by minc, and the width becomes hht + minc.

  The maximum / minimum value detection circuit 52 knows the normal active width hht in which the horizontal synchronization signal is high when the vertical synchronization signal is low, from the vertical / horizontal synchronization signal, the clock signal, and the data enable signal. When the vertical synchronization signal is high, the first and second horizontal synchronization widths are counted in units of clocks, and the active width hht is subtracted. Then, (maxc-minc) and minc are calculated, and the difference (maxt-mint) and the minimum value mint between the maximum value and the minimum value of the pixel can be detected, respectively, and maxt and mint are obtained and output from this.

(Third embodiment)
In the first embodiment, the maximum value to be transmitted is the maximum value among the individual maximum values of red, green, and blue, and the minimum value is the minimum value among the individual minimum values of red, green, and blue. You may send the minimum value.

  At that time, the following partial changes are necessary with respect to the configuration described in the first embodiment.

(A) The “maximum / minimum detection and RGB conversion circuit 41” performs the following processes (3) and (4) for the period of the vertical synchronization signal vsync, that is, for each screen.

(3) Detection of maximum and minimum pixel values for each screen
The maximum value of brightness is detected for each pixel of red, green, and blue in one screen, and rounded to 6 bits as in equation (2), and set to maxr, maxg, and maxb, respectively.
Similarly, the minimum value of brightness is detected for each pixel of red, green, and blue in one screen, and is rounded to 6 bits as in equation (2) to be minr, ming, and minb, respectively.

(4) RGB conversion Each 10-bit data of rgb input is assigned to 256 gradations, that is, 8 bits, between the maximum and minimum values of red, green, and blue obtained earlier. Is the transmission data.
R = INT [255 * (r-minr) / (maxr-minr) +0.5] (3) '
G and B are similar equations.

(B) The horizontal synchronization width modulation circuit 42 performs the following processing.
As shown in aa) of FIG. 6, the period during which the vertical synchronizing signal VSYNC is active is set to be six periods of the horizontal synchronizing signal HSYNC. The horizontal synchronization period is hlt as shown in FIG. 6 bb), and the high active period is usually hht. Based on the maximum / minimum values for each red, green, and blue from the “maximum / minimum detection and RGB conversion circuit 41”, when the vertical synchronization signal is in the high period in this embodiment, the width of the first to sixth horizontal synchronization signals is variable. To indicate maxr, minr, maxg, ming, maxg, and ming, respectively.

(E) The maximum / minimum value detection circuit 52 performs the following processing in the vertical synchronization cycle.
From the vertical / horizontal synchronization signal, the clock signal, and the data enable signal, the normal active width hht when the horizontal synchronization signal is high when the vertical synchronization signal is low is known. When the vertical synchronization signal is high, the first to sixth horizontal synchronization widths are counted in units of clocks, and the active width hht is subtracted for each. Then, the maximum value and the minimum value maxr, minr, maxg, ming, maxg, ming for each red, green, and blue can be detected and output.

(F) The rgb conversion circuit 53 performs the following processing.
The display data rr, gg, and bb of 10 bits each of red, green, and blue are reproduced from the transmission data of each RGB 8 bits and the maximum and minimum values of each 6 bits pixel of red, green, and blue. Red rr is calculated by the following formula.
rr = 16mintr + (maxr-minr) R / 16 (4) '
Green gg and blue bb are calculated using the same formula. These values are the display image 231.

  As described above, in the first embodiment, the maximum value and the minimum value of brightness are obtained from video data input in units of screens, and the video data within the effective range is reassigned to the number of gradations that can be transmitted, and the maximum and minimum values are reassigned. By transmitting and decoding together with the value, there is an effect of increasing the number of gradations of the display data. In particular, the effect of increasing the number of gradations becomes remarkable when the screen is entirely dark or bright. Furthermore, there is an effect that the maximum and minimum values of the screen unit can be processed in real time by transmitting the maximum value and the minimum value of the brightness multiplexed on the synchronization signal.

  In addition, it is a general idea that such maximum and minimum values are transmitted by asynchronous communication with a synchronous signal or video signal. However, in such a method, the maximum and minimum values are transmitted to which screen transmission data. On the other hand, there is a drawback that it is difficult to know whether it is effective. In this embodiment, the relationship between the maximum / minimum values and the display data of the screen can be matched by multiplexing and transmitting the synchronization signal.

  When the gradation of the color reproducibility of the display device (e.g., equivalent to 10 bits each of RGB) is higher than the gradation of the video signal from the IRD (e.g., equivalent to 8 bits each of RGB), the minimum and maximum data are added to the video signal. In this way, the entire color range to be expressed by the display device is re-mapped to an effective video signal to maximize the color reproducibility.

  Conventionally, of the data to be transmitted, data between 0 and the minimum value and between the maximum value and 255 is not displayed even if it is transmitted and is wasted. In this embodiment, only the effective display data is transmitted to improve the color gradation of the display device.

  At that time, the minimum and maximum values are represented by changing the width of the synchronization signal, and information is transmitted in real time. Although such information can be transmitted using the communication function, the control information and the display data can be reliably linked by multiplexing the information with the synchronization signal.

  In the second embodiment, sending differential data has the effect of reducing the amount of data compared to sending the maximum value except when the minimum value is 0.

  In the third embodiment, the maximum value and the minimum value for each RGB are obtained, the image data within the effective range is reassigned to the number of gradations that can be transmitted for each RGB, and transmitted and decoded together with the maximum and minimum values. Even when the color balance of which color is extremely bright or dark is bad, there is an effect of increasing the number of gradations of the display data.

  This embodiment can also be realized by a computer executing a program. Also, means for supplying a program to a computer, for example, a computer-readable recording medium such as a CD-ROM recording such a program, or a transmission medium such as the Internet for transmitting such a program is also applied as an embodiment of the present invention. Can do. A computer program product such as a computer-readable recording medium in which the above program is recorded can also be applied as an embodiment of the present invention. The above program, recording medium, transmission medium, and computer program product are included in the scope of the present invention. As the recording medium, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

It is a color space reproducibility diagram that best represents the first embodiment of the present invention. It is a figure which shows the relationship between the color space of the transmission data before the process of 1st Embodiment. 1 is an overall block diagram of a system to which a first embodiment is applied. It is a detailed block diagram of a part of a system to which the first embodiment is applied. FIG. 5 is a timing chart for explaining FIG. 4 in the first embodiment. It is a timing diagram of a 3rd embodiment.

Explanation of symbols

11 Tuner
12 Demodulator circuit
13 Demultiplexer
14 AV decoder
15 color conversion circuit
17 CPU
18 memory
161 Video transmitter
221 video receiver
41 Maximum / minimum detection and RGB conversion circuit
42 Horizontal sync width modulation circuit
43 TMDS transmitter IC
51 TMDS receiver IC
52 Maximum / minimum value detection circuit
53 rgb conversion circuit

Claims (15)

Detection means for detecting the maximum and minimum pixel values of the video data;
First conversion means for converting the pixel value of the video data between the maximum value and the minimum value to a maximum gradation that can be transmitted;
Transmitting means for transmitting the converted video data and transmitting information capable of reproducing the maximum value and the minimum value;
Receiving means for receiving video data and information transmitted by the transmitting means;
A video data processing apparatus, comprising: second conversion means for performing gradation conversion into display data to be displayed on a display device based on the received video data and information. The detection means detects the maximum value and the minimum value of the pixel value of the video data for each display screen,
The video data processing apparatus according to claim 1, wherein the transmission unit transmits information capable of reproducing a maximum value and a minimum value for each display screen.   3. The video data processing apparatus according to claim 1, wherein the transmission unit transmits the converted video data and transmits information on the maximum value and the minimum value.   3. The video data processing apparatus according to claim 1, wherein the transmission unit transmits the converted video data and transmits information on a difference between the maximum value and the minimum value and a minimum value. The detection means detects the maximum and minimum pixel values for each color of the video data,
The transmission means transmits information capable of reproducing the maximum value and the minimum value for each color,
5. The method according to claim 1, wherein the second conversion unit performs gradation conversion for each color into display data to be displayed on the display device based on the received video data and information. The video data processing apparatus described.   6. The video data processing apparatus according to claim 5, wherein the processing for each color is processing for each of red, green, and blue.   The video data processing apparatus according to claim 1, wherein the transmission unit multiplexes and transmits information that can reproduce the maximum value and the minimum value on a synchronization signal. The transmission means transmits a horizontal synchronization signal by changing an active width of the horizontal synchronization signal according to information capable of reproducing the maximum value and the minimum value,
8. The video data processing apparatus according to claim 7, wherein the second detection unit detects the maximum value and the minimum value according to an active width of the horizontal synchronization signal.   The transmission unit transmits the vertical synchronization signal and the horizontal synchronization signal by changing the active width of the horizontal synchronization signal during a period in which the vertical synchronization signal is active according to information capable of reproducing the maximum value and the minimum value. The video data processing apparatus according to claim 8. Detection means for detecting the maximum and minimum pixel values of the video data;
Conversion means for converting the pixel value of the video data between the maximum value and the minimum value into a maximum gradation that can be transmitted;
A video data processing apparatus comprising: transmission means for transmitting the converted video data and transmitting information capable of reproducing the maximum value and the minimum value. Receiving means for receiving video data and receiving information capable of reproducing the maximum and minimum pixel values of the video data;
A video data processing apparatus comprising: conversion means for performing gradation conversion into display data to be displayed on a display device based on the received video data and information. A transmission means for expressing and transmitting data by changing the active width without changing the period of the synchronization signal;
A video data processing apparatus comprising: a detecting unit that receives the transmitted synchronization signal and detects data from a change in an active width of the synchronization signal. A detection step of detecting a maximum value and a minimum value of pixel values of video data;
A conversion step of converting the pixel value of the video data between the maximum value and the minimum value to a maximum gradation that can be transmitted;
A video data processing method comprising: transmitting the converted video data and transmitting information capable of reproducing the maximum value and the minimum value. A reception step of receiving video data and receiving information capable of reproducing the maximum and minimum pixel values of the video data;
A video data processing method comprising: converting a gradation into display data to be displayed on a display device based on the received video data and information. A transmission step of expressing and transmitting data by changing the active width without changing the period of the synchronization signal;
A video data processing method comprising: a detecting step of receiving the transmitted synchronization signal and detecting data from a change in an active width of the synchronization signal.

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