KR200150134Y1 - Automatic gain control system for a digital camcorder - Google Patents

Abstract

The object of the present invention is a gain automatic control system of a digital camcorder which digitalizes a captured video signal to automatically control gain. The present invention provides an analog / digital conversion system for converting an input captured video signal into a digital signal and outputting the digital signal. Means, an evaluation value calculating means for calculating an evaluation value of a digital image pickup signal output from the analog / digital conversion means, a microcomputer for setting a gain level by comparing the evaluation value calculated by the evaluation value calculating means with a set reference value; And a gain calculating means for automatically calculating the gain by distributing and summing the evaluation value calculated by the evaluation value calculating means and the gain level set by the microcomputer to a predetermined value.

Description

Gain automatic control system of digital camcorder

1 is a block diagram of a gain automatic control system of a conventional camcorder.

2 shows the relationship between the gain control value and the gain of FIG.

3 is a block diagram of a gain automatic control system of the present invention digital camcorder.

FIG. 4 is a screen division diagram for explaining FIG. 3.

* Explanation of symbols for main parts of the drawings

103: automatic gain control unit 108: micom

109: digital / analog converter 200: analog / digital converter

201: evaluation value calculation unit 202: gain calculation unit

The present invention relates to a camcorder, and more particularly, to an automatic gain control system of a digital camcorder for digitalizing a captured image signal to automatically control gain.

As shown in FIG. 1, a gain automatic control system of a conventional camcorder includes an imaging tube (102) for converting and outputting an image signal of a luminance signal through a lens (100) and an aperture (101), and the input gain control signal. The automatic gain control unit 103 for automatically controlling the gain of the image signal picked up by the image pickup tube 102 and outputting a predetermined level of the captured image signal, and buffering the captured image signal controlled by the automatic gain control unit 103. The first buffer 104, the first integrator 105 for integrating and outputting the video signal output from the first buffer 104, and the video signal integrated in the first integrator 105 The second buffer 106 that is buffered, the second integrator 107 that integrates and outputs the image signal buffered by the first buffer 104, and the value integrated by the second integrator 107. From the microcomputer 108 to control the operation of the entire system, and the microcomputer 108 A digital / analog converter 109 for converting the outputted signal into an analog signal and outputting the converted signal; a third buffer 110 for buffering the value output from the digital / analog converter 109; and the second and second buffers. Comparing unit 111 outputs the gain control signal by comparing the values respectively output from the three buffers (106, 110).

The operation of the gain automatic control system of the conventional camcorder configured as described above will be described with reference to FIG. 2. When the luminance signal of the subject is input to the imaging tube 102 through the lens 100 and the aperture 101, the imaging tube 102 ) Converts the luminance signal through the diaphragm 101 to the automatic gain control unit 103 by converting the captured image signal.

The automatic gain control unit 103 controls the gain of the image signal captured by the imaging tube 102 to output a predetermined level of the captured image signal, which is buffered through the first buffer 104 and then The first and second integrating units 105 and 107 are respectively applied.

The first integrator 105 integrates the captured image signal buffered in the first buffer 104 and the integrated signal is buffered through the second buffer 106 and then the inverting terminal (-) of the comparator 111. To apply.

In addition, the second integrating unit 107 integrates the captured image signal buffered in the first buffer 104 and applies it to the microcomputer 108.

Accordingly, the microcomputer 108 recognizes the value integrated in the second integrator 107 and compares the gain control value with the set reference value to the digital / analog converter 109.

The digital / analog converter 109 converts the gain control value output from the microcomputer 108 into an analog signal, and the converted gain control value is buffered through the third buffer 110 and then of the comparator 111. Applied to non-inverting terminal (+).

The comparison unit 111 compares the signals output from the second buffer 106 and the third buffer 106 and applies the result value to the automatic gain control unit 103 and accordingly the image captured by the imaging tube 102. The gain of the signal is automatically controlled.

However, such a gain control system of a conventional camcorder controls the gain of a captured image signal by using an analog signal, and therefore, the gain is affected by noise generated in a peripheral digital circuit, thereby affecting the screen.

Therefore, an object of the present invention is to provide a gain automatic control system of a digital camcorder for automatically controlling gain by digitalizing a captured image signal.

The present invention has an analog / digital converting means for converting an input captured image signal into a digital signal and outputting it, an evaluation value calculating means for calculating an evaluation value of the digital captured image signal output from the analog / digital converting means; A microcomputer for setting a gain level by comparing the evaluation value calculated by the evaluation value calculating means with the set reference value, and distributing the evaluation value calculated by the evaluation value calculating means and the gain level set by the microcomputer to a predetermined value. This is achieved by configuring a gain calculating means for automatically calculating the gain by summing up. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is an image pickup tube 102 for converting a luminance signal through the lens 100 and the aperture 101 into a captured image signal and outputting the image signal as shown therein. The automatic gain control unit 103 outputs the level of the image signal picked up at the predetermined level according to the input gain, and the analog output unit converts the captured image signal output from the automatic gain control unit 103 into a digital signal and outputs the digital signal. The digital value conversion unit 200, an evaluation value calculation unit 201 for calculating the calculated evaluation value of the digital video signal converted by the analog / digital conversion unit 200, and the evaluation value calculation unit 201 The microcomputer 108 which sets the gain level by comparing the estimated value with the set reference, and the gain level calculated by the evaluation value calculation unit 201 and the gain level by the microcomputer 108 are distributed and summed to a predetermined value to obtain a gain. To It constitutes a resistance (R1) (R2) to the gain calculating unit 202 for calculating the same.

Referring to Figure 4 attached to the operation and effects of the present invention configured as described above in detail when the luminance signal of the subject is input to the imaging tube 102 through the lens 100, the aperture 101, the imaging tube 102 Converts the luminance signal through the diaphragm 101 into a captured image signal and applies it to the automatic gain control unit 103.

The automatic gain control unit 103 controls the gain of the image signal captured by the imaging tube 102 to output a predetermined level of the captured image signal, and the output captured image signal is a digital image through the analog / digital change unit 200. The signal is converted and applied to the evaluation value calculation unit 201.

The evaluation value calculation unit 201 detects the imaging signal level in the light conserving region of the digital captured image signal output from the analog / digital change unit 200, and then forms an AE detection signal for exposure control and a predetermined focus. A mid-range level is detected among the image pickup signals in the area and an AF detection signal for focus control is formed.

In addition, the evaluation value calculation unit 201 detects each color signal level of the digital image pickup signal output from the analog / digital conversion unit 200 and forms an AWB detection signal for height balance control.

As shown in FIG. 4, the evaluation value calculator 201 divides the screen into first, second, and third regions, calculates an integral value of data for each region, and then applies it to the microcomputer 108. .

Accordingly, the microcomputer 108 recognizes the evaluation value output from the evaluation value calculation unit 201, and when the sum of the data of the first, second, and third regions and the received evaluation value are general subjects, the signal level is small. In the case where the value is greater than 80, and in the case where the signal level is greater, the value is less than 80, the value V1 (V2) output through the digital / analog converter 109 is controlled.

Accordingly, the gain of (a) shown in FIG. 3 is (R2 * V1) / (R1 + R2) + (R1 * V2) (R1 + R2).

As described in detail above, by controlling the gain of the captured image signal using digitalized information, the effect of reducing the amount of hardware and reducing the amount of hardware by reducing the amount of hardware, and miniaturization and low cost of the product can be improved. It can be effective.

Claims (1)

An analog / digital converting means for converting an inputted captured image signal into a digital signal and outputting the same; an evaluation value calculating means for calculating an evaluation value of the digital captured image signal output from the analog / digital converting means; A microcomputer that sets the gain level by comparing the calculated evaluation value with the set reference value, and a gain calculation that automatically calculates the gain by distributing and summing the evaluation value calculated by the evaluation value calculating means and the gain level set by the microcomputer to a predetermined value. Gain control system of a camcorder, characterized in that it comprises a means.