KR950006040B1 - Level display circuit of brightness signal in a video camera - Google Patents

Abstract

The circuit displays luminance level of input image so that an operator can identify the luminance level of image. The circuit comprises a luminance signal detector (1) for extracting luminance signal from a video signal, a level adjuster (2) for adjusting level of the luminance signal detected by the luminance signal detector (1), an A/D converter (3) for converting output signal of the level adjuster (2) into digital luminance signal, a micom (4) for generating status signals according to the digital luminance signal, a latch (5) for latching the status signal generated by the micom (4), and a status signal display (6) for displaying the status signal.

Description

Luminance signal level display circuit of video camera

1 is a block diagram showing a luminance signal level display circuit according to the present invention.

2 is a view showing a display state of the state output unit shown in FIG.

3 is a flowchart showing the operation of the microcomputer shown in FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera, and more particularly, to a luminance signal level display circuit for displaying a magnitude of light incident on a camera so that a user can easily recognize it.

In a video camera, it is necessary to maintain an appropriate exposure state in order to faithfully reproduce an image of a subject. To this end, recent video cameras employ an auto iris zoom lens. It detects the maximum or average value of the luminance signal for a certain period of time and automatically adjusts the iris or ND FILTER of the video camera so that a proper exposure can be obtained simply by pointing the camera at a subject.

The following problems appear in such a video camera.

First, since the luminance signal level of the image signal displayed on the EVF (Electronic View Finder) of the video camera can be changed by the brightness or contrast controller attached to the EVF, it is judged by the amount of light actually incident and the displayed image signal. There may be a difference with the amount of light. Therefore, it is difficult to determine the exact amount of light only by the video signal displayed on the EVF, and it is inconvenient to check the iris value whenever necessary.

Second, if the user wants to get special effects that cannot be achieved in autoexposure mode, the user should shoot while adjusting the iris manually. Since the human eye is very sensitive to the change of brightness, There may be a significant difference from the magnitude of the change in the amount of light.

As described above, there is a problem that it is difficult and inaccurate to detect the amount of light incident on the camera while viewing the image displayed on the EVF.

An object of the present invention is to provide a luminance signal level display circuit that allows the user to easily sense the amount of light incident on the camera with the naked eye.

According to an aspect of the present invention, a luminance signal level display circuit includes a luminance signal extracting unit configured to extract a luminance signal by introducing an image signal of a photoelectrically converted object; A level adjusting unit for adjusting the extracted luminance signal to an appropriate value; A microcomputer inputting the digitally converted luminance signal and determining and outputting a state output corresponding thereto; A latch unit for latching the state output until a next state output is output; And a state output unit for displaying the magnitude of the state output latched by the latch unit. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing an embodiment of a luminance signal level display circuit according to the present invention. In FIG. 1, the apparatus includes a luminance signal extracting section 1, a level adjusting section 2, an analog / digital converting section 3, a microcomputer 4, a latch section 5, and a state output section 6. .

The luminance signal extractor 1 extracts a luminance signal by introducing an image signal of a photoelectrically converted subject.

The level adjuster 2 stores the extracted luminance signal at an appropriate value to match the dynamic range of the analog / digital converter 3.

The analog / digital converting section 3 inputs the level adjusted brightness signal through the level adjusting section 2 and outputs the digitally converted brightness signal.

The microcomputer 4 inputs the luminance signal digitally converted through the analog / digital converter 3, and discriminates and outputs a state output corresponding thereto.

The latch section 5 latches the state output output from the microcomputer 4, and the latched value is held until the next state output is output.

In this case, the period in which the state output is output from the state output unit 6 is determined by a timer interrupt in the microcomputer 4 or a clock provided to a separate timing generator (not shown), for example, the microcomputer 4. It can be determined by the counter which counts the signal and outputs an interrupt signal to the microcomputer 4 when the count value reaches a predetermined number.

Whenever an interrupt by an internal timer interrupt or an interrupt by an external timing generator occurs, the microcomputer 4 inputs a digitally converted luminance signal output from the analog / digital converter 3 and outputs the state output thereof. And the output to the latch unit 5 is determined.

The state output unit 6 displays the magnitude of the state output latched by the latch unit 5 so that the user can visually recognize it.

2A and 2B show an example of output of the state output unit. 2A shows a case where the state output unit 6 is composed of LEDs arranged in a predetermined number of lines. When the status output unit 6 is composed of LEDs, different numbers of LEDs may be lit to correspond to the status outputs.

The number of LEDs needed (N) is equal to the maximum number of status outputs.

2b shows a case where the state output unit 6 is a state display area set in a certain portion of the EVF or the monitor. When the status output section 6 is set as the status display area, it is expressed as the length of the status bar which varies in accordance with the status output.

3 is a flowchart showing the operation of the microcomputer 4 shown in FIG. Table 1 shows an example of the state output for the luminance signal. Here, it is assumed that the maximum value of the state output is 10, and the luminance signal is linearly quantized.

TABLE 1

(Here, IRE is a unit for expressing the level of the video signal.)

At this time, the interval between each step, that is, the range of the luminance signal corresponding to each step may be appropriately adjusted.

That is, the number of steps may be increased or decreased or the interval between each step may be divided non-linearly.

Step 200 is a process of reading an analog / digital converted brightness signal into the microcomputer 4, and steps 210 to 300 are processes of measuring the magnitude of the brightness signal and determining a state output to be output to the latch unit 5. Step 310 is a process of outputting the state output determined in steps 210 to 300.

The microcomputer 4 reads the analog / digital converted luminance signal from the analog / digital conversion unit 3 at the first stage of the state output generation program.

It is determined whether or not the magnitude of the digitally converted luminance signal corresponds to step 0. FIG. That is, it is determined whether or not the magnitude of the digitally converted luminance signal is 0 IRE or less. (Step 211) If the magnitude of the digitally converted luminance signal is 0 IRE or less, the state is to be outputted to the latch unit 5 because it is in step 0. Prepare 0 as the output and proceed to step 310.

If the magnitude of the digitally converted luminance signal is equal to or greater than 0 IRE, the process proceeds to step 220 to determine whether or not it is step 2. This operation is sequentially performed up to 300 steps to determine the status output. Operations of steps 220 to 300 are the same as operations of step 210, and thus a detailed description thereof will be omitted.

The state output determined in steps 210 to 300 is output to the latch unit 5 in step 310.

As described above, the luminance signal level display circuit according to the present invention has an advantage of enabling the photographer to recognize the luminance level of the input image signal accurately so as to quickly respond to changes in the illumination environment for the subject.

Claims (7)

A luminance signal level display circuit for displaying the amount of light incident on a video camera, the luminance signal level display circuit comprising: a luminance signal extracting unit for extracting a luminance signal by inputting a video signal of a loaded object; A level adjusting unit adjusting the extracted luminance signal to an appropriate value; An analog / digital converter configured to input the level-adjusted luminance signal and output a digitally converted luminance signal; A microcomputer inputting the digitally converted luminance signal and determining and outputting a state output corresponding thereto; A latch unit for latching the state output until a next state output is output; And a status output section for displaying the magnitude of the status output latched by the latch section. 2. The luminance signal level display circuit according to claim 1, wherein the luminance signal extracting unit outputs an average value of the luminance signal for a predetermined period. 2. The luminance signal level display circuit according to claim 1, wherein the luminance signal extracting unit outputs an average value of the luminance signal for a predetermined period. 2. The luminance signal level display circuit according to claim 1, wherein the microcomputer outputs a state output obtained by linearly quantizing a digitally converted luminance signal input thereto. 2. The luminance signal level display circuit according to claim 1, wherein the microcomputer outputs a state output obtained by non-linear quantization of the digitally converted luminance signal input thereto. 2. The luminance signal level according to claim 1, wherein the state output unit includes LDEDs arranged in a predetermined number of lines, and the luminance signal levels are displayed by lighting different numbers of LEDs according to the size of the state outputs. Display circuit. The display apparatus of claim 1, wherein the state output unit sets a portion of the EVF or the monitor screen as the luminance signal level display area, and displays the luminance signal level as a status bar having a different length corresponding to the size of the state output. A luminance signal level display circuit.