JPS61258566A - Video signal processing system - Google Patents

Abstract

PURPOSE:To adjust optionally the characteristic of a camera by using a table memory LUT to apply each signal processing of the television camera and rewriting data on the table memory from an external circuit to satisfy the request of the operator. CONSTITUTION:When the operator of camera operates a gamma correction characteristic operation input device 9 to increase the gain at a low level of a video signal for photographing an entirely dark object, operation information 11 is inputted to a central processing unit 12 and gamma correction is applied based on a program of a memory 14 and the corresponding data of nonlinear signal processing LUTs 31-33 at white level compression. Then the write mode is obtained for LUTs 30-33 by using a read/write control signal 17, corresponding data is outputted as write data 16 while each address is being accessed by an address signal 15 to rewrite the internal data. Thus, the gain of the dark component is increased for output video signals 40-42 and the processing characteristic is changed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to video signal processing for a television camera.

(Prior art and its problems) Video signal processing for conventional television cameras.

This is done using an electronic circuit designed according to the processing content. A conventional example is shown in FIG.

In this conventional example, the gamma correction circuit 2
Then, processing is performed to provide nonlinear characteristics between input and output as shown in FIG. Next, the high level part of the output of the gamma correction circuit 2 is processed by the white compression circuit 3.

Compression is performed using the input/output characteristics shown in FIG. 3, and the portion of this output that exceeds a certain level is clipped by the white clipping circuit 4 using the input/output characteristics shown in FIG. As described above, depending on each electronic circuit.

A television camera video signal is processed.

Since each signal processing conversion is implemented in hardware in this way, it is difficult to faithfully realize nonlinear signal conversion such as gamma correction, and it is difficult to faithfully realize nonlinear signal conversion such as gamma correction. is being carried out. Also,
It is also difficult to maintain stable input/output characteristics due to the temperature characteristics of the element. In order to solve these problems, the video signal is converted from analog to digital (hereinafter referred to as A/D), and the RO
LU by M (Readonly Memory)
There is also a conventional example using T (Look up Table). This conventional example is shown in FIG. Furthermore, what is LUT?
As shown in Figure 6, it is a table memory in which the data value stored at each address ai is a function f(ai) of the address value, and the address is specified using a digitized input signal, and the accessed data is used as output. and signal conversion with arbitrary input/output characteristics. By storing signal processing data with arbitrary characteristics in which LUT 7 and inputting the A/D-converted video signal 6 to the address, a signal 8 obtained by processing the video signal 6 with arbitrary characteristics can be obtained. The arbitrary characteristic data may be, for example, the gamma correction characteristic shown in FIG. 2, the white compression characteristic shown in FIG. 3, or a characteristic considering a plurality of these characteristics.

As a result, nonlinear processing, which was a problem in the conventional example, can be
Accurate processing can be performed depending on the data stored in the UT, and stable processing can be performed even with temperature fluctuations.

Furthermore, multiple processes can be performed using one LUT.

However, in the video signal processing of a television camera, it is necessary to flexibly change the processing characteristics depending on the environment in which the camera is used. For example, the object to be imaged, which was processed using the gamma correction characteristic a shown in FIG. 7, has changed to something with a strong contrast.

There may be a request to change the characteristics to suppress the output relative to the input, such as the gamma correction characteristics shown in FIG. 7, and the conventional method using ROM has a problem.

(Objective) The present invention is characterized in that each signal processing of a television camera is performed accurately and stably using a table memo IJ (LUT), and furthermore, the data in this table memory can be rewritten from an external circuit. , the purpose is to make it possible to arbitrarily adjust the characteristics of the camera according to the operator's requirements.

(Embodiment) The present invention basically processes the video signal as a digital signal by performing A/D conversion, whereas conventionally the video signal is processed as an analog signal. The LUT also includes a memory (for example, R
A M (Random Access Memory)
).

The outline of this invention will be explained below with reference to FIG.

Gamma correction characteristic operation input device 9. Operation information 11 of the operator of the television camera is inputted to the central processing unit 12 from the white compression characteristic operation input device 10 and the like.

Further, program data 13 is inputted to the central processing unit 12 from the program memory 14 . From this central processing unit 12, the address signals 15 of the nonlinear signal processing LUTs 31, 32, 33 corresponding to the R, G, B channels of the video signal are sent to the JG, B address signal changeover switches 25, 26, 27. is input. The write data 16 of the one-sided valve linear signal processing LUT 31, 32, and 33 is as follows.

The data is input from the central processing unit 12 to R, G, and H data signal changeover switches 37, 38, and 39. A=4 above
= Switching control signal 1 for dress signal changeover switches 25, 26.27 and data signal changeover switches 37, 38, and 39
8, each changeover switch 25 from the central processing unit 12;
26.

27.37 and 38.39 to control switching. In addition, the above nonlinear signal processing LUTs 31, 32, 33
Ride/write control signal 17 is from central processing unit 12 .

The signals are input to nonlinear signal processing LUTs 31 and 32.33.

Next, the input video signals 19, 20 of R, G, and B channels are
゜21 are respectively converted into digital signals by A/D converters 22, 23, and 24, and then sent to the address signal changeover switch 2.
Entered on 5.26.27. From the address signal changeover switches 25, 26, and 27, L for nonlinear signal processing is connected.
Address signals 28, 29.3 of UT31, 32.33
0 is input to the addresses of the nonlinear signal processing LUTs 31, 32, and 33. This nonlinear signal processing LUT31
, 32.33 are connected to data signal changeover switches 37, 38.39, and from the data signal changeover switches 37, 38.39,
Output video signals 40, 41.4 of R, o, and B channels
2 is output. This output video signal can be converted to D/
A converters 43, 44.

45 may be used to convert it into an analog signal. In addition.

When using a memory with separate input data and output data terminals for nonlinear signal processing LUT 3], 32, 33, nonlinear signal processing LUT 31, 32 from the central processing unit is used for the input data terminal. It is sufficient to directly connect the write data 16 of .33 and make the data from the output data terminal the output video signals 40, 4], 42.

, the data signal changeover switches 37, 38, and 39 become unnecessary. The operation of the present invention shown in FIG. 1 will be explained below. First, LUT for nonlinear signal processing of each channel.
31, 32, and 33 store characteristic data when gamma correction is performed using characteristic a shown in FIG. 9 and white compression is performed using characteristic a shown in FIG. 10. 26, 27 are input video signals 19, 20 .
21, and the data signal changeover switches 37, 38 .
39 is electrically connected to the output video signals 40, 4.1.42, and the nonlinear signal processing LUTs 31, 32.33 are set to serial read mode by the read/write control signal 17 from the central processing unit 12, and are digitized. input video signal 19,
20.21 is LUT31 for nonlinear signal processing.

It is assumed that the addresses 32 and 33 are designated, and the accessed data becomes output video signals 40, 41.4-2, and is subjected to signal processing. Next, the camera operator tries to increase the low-level gain of the video signal in order to take a picture of an object that is completely dark, and tries to change the gamma correction characteristic from a to gamma correction characteristic shown in Figure 9. Operate the operation input device 9.

Then, the operation information 11 is input to the central processing unit 12, and the central processing unit 12 performs the following operations based on the program stored in the program memory 14.

(1) LU for nonlinear signal processing when white compression is performed with the characteristic a of FIG. 10 after gamma correction has been performed with the characteristic of FIG. 9
It is calculated by calculating the corresponding data of T31, 32, and 33. (Calculating means) (2) Address signal changeover switches 25, 26, 27 are configured to connect the address signals 28, 29, 30 of the nonlinear signal processing LUTs 31, 32, 33 and the address signal 15 from the central processing unit 12. control. (Control signal generation means) (3) Read/write control signal 17 to set the nonlinear signal processing LUTs 31, 32, and 33 to write mode.
Output. (Control signal generation means) (4) Data signal changeover switch 3 connects input/output data 34, 35, 36 of nonlinear signal processing LUT 31, 32, 33 and write data 16 of the LUT.
Control 7°38.39. (Control signal generation means) (However, this operation is not necessary when using separate input data terminals and output data terminals for nonlinear signal processing LUT 3 and 32.33.) (5) Nonlinear signal While accessing each address of the processing LUTs 31, 32, 33 using the address signal 15, the corresponding data obtained in (1) above is sent to the nonlinear signal processing LUTs 31, 32, 33.
33 as write data 16, and rewrites the internal data of each corresponding address. (Output means) (6) Set the nonlinear signal processing LUTs 31, 32, and 33 to the original read mode using the read/write control signal 17.

The address signal changeover switches 25, 26, 27 and the data signal changeover switches 37, 38, 39 are also returned to their original states by the changeover switch=8-switch control signal 18.

(Control Signal Generating Means) As a result of the above, the output video signals 40, 41, and 42 have increased gains in dark areas, and the processing characteristics can be easily changed.

In addition, when imaging a subject whose video signal has a wide dynamic range from low level to high level, the white compression characteristic operation input device 10 is operated so that the high level part is not clipped as much as possible. Characteristics a to b
Even in the case of changing the gamma correction characteristics, the central processing unit 12 calculates the characteristics and rewrites and stores the data in the nonlinear signal processing LUTs 31, 32, and 33. ,realizable. When G is the function that calculates the data of the gamma correction characteristic, K is the function that calculates the data of the white compression characteristic, X is the address of the nonlinear processing LUT, and y is the data. 1. Characteristic change in video signal processing of the present invention A flowchart of the operation is shown in FIG.

As described above, by using a rewritable memory in the LUT and creating and transferring the data using software, it is possible to immediately change the characteristics in video signal processing without changing the hardware at all. In addition, processing of non-linear characteristics such as gamma correction, which was difficult with the method of processing video signals as analog signals without using T and UT, is also difficult in the present invention, as described above. This can be easily achieved by simply storing the indicated data in an LUT, and accurate and stable processing against temperature changes is possible. Furthermore, as shown in Figure 1, by preparing a program that creates characteristic data that takes into account multiple processes,
Multiple processes such as gamma correction and white compression can be performed with one LUT, and the characteristics can be controlled individually, so one piece of hardware is required for each process, unlike conventional processing using analog signals. The circuit configuration can be simplified without requiring the above. In addition, in video signal processing, it is common to change gamma correction, white compression, white clipping, etc. on all three channels at the same time in order to change these characteristics.At this time, in conventional analog signal processing,
The hardware of each channel had to be changed equally, but as shown in Figure 1, in the present invention, the LUTs of three channels can be controlled by one central processing unit. By simply providing one piece of operating information to the device, it is possible to easily change the characteristics of the three channels equally.

(Effects) According to the present invention, in each process of a television camera, processing having arbitrary characteristics such as nonlinear characteristics can be easily and accurately realized, and arbitrary changes in the characteristics can also be realized.
This can be done immediately without changing the hardware. Furthermore, by controlling the LUTs of three channels with one control means, special changes can be made equally to all three channels at the same time.

Furthermore, by performing multiple processes with one LUT.

The circuit can be made simpler than before.

[Brief explanation of the drawing]

FIG. 8 is a block diagram of a conventional video signal processing device. Figure 2 is an input/output characteristic diagram of the gamma correction circuit, Figure 3 is an input/output characteristic diagram of the white compression circuit, Figure 4 is an input/output characteristic diagram of the white clip circuit, and Figure 5 is a diagram of the input/output characteristics of the white clip circuit. ), FIG. 6 is a diagram showing the relationship between LUT address and data, FIG. 7 is a gamma correction characteristic diagram, FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 9 10 is a gamma correction characteristic diagram, FIG. 10 is a white compression characteristic diagram, and FIG. 11 is a flowchart showing the characteristic changing operation procedure of the present invention. 9: Gamma correction characteristic operation input device, 10: White compression characteristic operation input device,] 2: Central processing unit, 14 Niprogram memory, 15, 28, 29, 30 Near address signal. 16: Write data, 17: Read/write control signal, 18: Switching control signal, 1.9, 20.21:
Input video signal, 22, 23. 24: A/D converter, 25, 26, 27 Near address signal changeover switch, 3], 32, 33: LUT for nonlinear signal processing, 34, 35. 36: Input/output data . 37.38.39: Data changeover switch, 40
,41. ．． 42: Output video signal.

Claims (1)

[Claims] A video signal characteristic conversion means that sets the data value stored at each address as a function of the address value, performs this address specification using a digitalized video signal input, and outputs the accessed data; a characteristic change information setting means for setting and generating characteristic change information necessary for changing the characteristic; and a calculation means for calculating an optimum data value corresponding to each address of the video signal characteristic conversion means according to the characteristic change information. , a control signal generating means for controlling the read/write mode of the video signal characteristic converting means, and a means for rewriting the data value of the video signal characteristic converting means into an output value of the calculating means according to the characteristic change information using the control signal. A video signal processing method characterized by having: