KR100867595B1 - Method for controlling wide dynamic range in camera - Google Patents

Abstract

A wide dynamic range control method of a camera is provided to prevent a flicker phenomenon normally while performing wide dynamic range operation. When a function of a wide dynamic range is performed, a preset flicker remove mode flag value is checked to detect whether the current operation mode is a flicker remove mode. If the detection result is a flicker remove mode, the wide dynamic range operation is performed by variably adjusting a long shutter speed and a short shutter speed to adjust the shutter speed at times of 1/50 second.

Description

How to control wide dynamic range in camera {Method for controlling wide dynamic range in camera}

1 illustrates an embodiment in which a flicker occurs in a general camera.

2 illustrates an embodiment in which flicker is removed from a typical camera.

3 illustrates a configuration of a camera to which the wide dynamic range control method according to the present invention is applied.

4 illustrates an embodiment of a method for controlling a wide dynamic range of a camera according to the present invention.

※ Explanation of code for main part of drawing

10 lens 11: iris

12: CD 13: Automatic Gain Adjuster

14 digital signal processing unit 15 CD drive unit

16: light detector 17: microcomputer

18: memory

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a wide dynamic range of a camera. For example, when a high brightness subject and a low brightness subject are simultaneously photographed under a luminescent light such as a fluorescent lamp, a wide dynamic range (WDR) operation is performed. The present invention relates to a method of controlling a wide dynamic range of a camera to prevent flicker from occurring.

FIG. 1 illustrates an embodiment in which flicker occurs in a general camera. For example, in a camera to which a typical 60 Hz NTSC system is applied, the exposure time of a CCD (CCD) is determined. The shutter speed to be set is set to 1/60 second in the normal shooting mode.

However, if a subject is photographed at a shutter speed of 1/60 second under a luminescent light such as a fluorescent lamp using an AC power source having a frequency of 50 Hz, for example, as shown in FIG. 1, the image screen is flickering. Flicker) phenomenon occurs.

That is, since fluorescent lamps using an AC power source having a 50 Hz frequency emit light when the AC power level is +/-, the fluorescent lamps emit light at 100 Hz cycles. Therefore, when shooting a subject at a shutter speed of 1/60 second, As shown in FIG. 1, at the second exposure time, a luminance value of a level lower than that of the first exposure time is output, and in particular, at a third exposure time, a luminance value of 0 level is output, so that the camera image screen is chewing gum. The flicker phenomenon occurs.

Accordingly, in the general camera, when the flicker removal mode is set in order to remove the flicker generated as described above, as shown in FIG. 2, the shutter speed of 1/60 second is 1/50 second. Since the variable speed is applied to the shutter speed, the subject can be normally photographed without flicker even under a fluorescent lamp having a light emission period of 100 Hz.

On the other hand, recently, when a high-luminance subject and a low-luminance subject exist simultaneously in the captured image, the shutter speed is set to a long shutter speed with a long exposure time of the CDD and a short exposure time of the CDC. (Short) By capturing and synthesizing the video frames to be photographed while alternating with the shutter speed, a wide dynamic range (WDR) operation is performed so that even a low luminance subject can be captured at a bright luminance level.

However, in a typical camera, since the flicker removal function and the wide dynamic range function are performed as separate functions, respectively, the flicker removal function is ignored, for example, while performing the wide dynamic range function. There is a problem in which the flickering of the image is repeated.

Accordingly, the present invention has been created to solve the above problems, for example, when performing a wide dynamic range (WDR) operation for simultaneously photographing a high-brightness subject and a low-brightness subject under a luminescent light such as a fluorescent lamp. The camera's wide dynamic to variably adjust the Long and Short Shutter Speeds to an integer multiple of the original value (e.g. 1/50) set to eliminate flicker, so that no flicker occurs. It is an object of the present invention to provide a range control method.

According to an aspect of the present invention, there is provided a method of controlling a wide dynamic range of a camera, the method comprising: detecting whether a current operating mode is a flicker removing mode when performing a function of a wide dynamic range; And if the detection result is the flicker removal mode, the wide shutter speed and the short shutter speed are variably adjusted to perform a wide dynamic range operation, and the adjustment value of the shutter speed is adjusted to an integer multiple of an inherent value set for flicker removal. Characterized in that comprises two steps to do,

In the first step, when the luminance level difference between the plurality of subjects existing in the captured image exceeds the reference value, the controller performs the function of the wide dynamic range, and detects whether the flicker removal mode flag is set immediately before. ,

Also, in the second step, if the flicker removal mode is performed, the wide shutter may be variably adjusted to a long shutter speed and a short shutter speed to perform a wide dynamic range operation, but the adjustment value of the shutter speed may be set to remove flicker. Variable to a multiple of the periodic value of a specific frequency,

In addition, as a result of the detection, if not in the flicker removal mode, by varying the long shutter speed and the short shutter speed to perform a wide dynamic range operation, the variable adjustment value of the shutter speed in a multiple of a period value of a specific frequency Characterized in that further comprises a step.

Hereinafter, a preferred embodiment of a method for controlling a wide dynamic range of a camera according to the present invention will be described in detail with reference to the accompanying drawings.

First, the wide dynamic range control method according to the present invention can be applied to various types of cameras. For example, in the camera to which the present invention is applied, as shown in FIG. 3, the lens 10 and the iris ( IRIS (11), CD (CCD) (12), automatic gain adjuster (13), digital signal processor (14), CD driver (15), light detector (16), microcomputer (17), and memory ( 18) and so forth.

On the other hand, in the microcomputer 17, for example, when performing a flickerless operation (Flickerless) in response to a user's request, the CD drive unit 15 is controlled to control the exposure time of the CD 12 The decision is made to variably adjust the shutter speed.

For example, as described above with reference to FIG. 2, when shooting a subject in a 60 Hz NTSC system under a fluorescent lamp using an AC power source having a 50 Hz frequency, 1/50 second or 1 / The shutter speed is adjusted to 100 seconds.

In addition, when performing the flicker removal operation as described above, the microcomputer 17 sets the corresponding identification information, for example, a flickerless mode flag to '1'.

On the other hand, in the light detector 16, for example, as shown in Fig. 4, after capturing a video frame of a captured image, the light detector 16 is divided into nine regions W1 to W9, respectively. The luminance level value for each divided region of the is detected.

In addition, the microcomputer 17 compares the detected luminance level values of each divided region and calculates a difference value. For example, the luminance level value of the third region W3 is the highest value. Corresponds to 80 of the luminance level (e.g., 100), the luminance level value of the fifth region W5 corresponds to 20 of the luminance level of the highest value, and the luminance level value of the other regions is the luminance of the highest value. When it corresponds to 40 of the level, the microcomputer 17 calculates a luminance level difference value of 60 between the third region and the fifth region.

In addition, in the microcomputer 17, when the luminance level difference value (for example, 60) of the third region and the fifth region calculated as described above exceeds a preset reference value, for example, 50 reference values. It is determined that the high brightness subject and the low brightness subject exist simultaneously in the captured image.

In addition, the microcomputer 17 performs a wide dynamic range (WDR) operation so that the high brightness subject and the low brightness subject can be normally photographed at the same time. For example, in the microcomputer 17, the CC By operating the driving unit 15, the long shutter speed operation to increase the exposure time of the CD and the short shutter speed operation to shorten the exposure time of the CD are alternately performed. The adjustment value of the shutter speed is variably adjusted to an integer multiple of the inherent value set for flicker removal.

For example, the microcomputer 17 performs a wide dynamic range operation when the current operation mode is the flicker removal mode and the shutter speed is adjusted to 1/100 second which is a multiple of the 1/50 second shutter speed. For this purpose, by adjusting the long shutter speed to 1/50 second, the exposure time of the CD is lengthened, and the short shutter speed is then adjusted to 1/200 to shorten the exposure time of the CD.

That is, as shown in FIG. 4, when the wide dynamic range operation is performed while the flicker removal mode is set, the long shutter speed is adjusted from 1/100 second to 1/50 second adjusted for the current flicker removal. Then, the short shutter speed is adjusted to 1/200 second.

Accordingly, when the long shutter speed of 1/50 second is applied as described above, the luminance value of the third region should be 80 to 160, but since the highest luminance level is 100, the luminance value is 100, not 160, whereas The luminance value of the fifth region is 20 to 40.

When the short shutter speed of 1/200 sec is applied, the luminance value of the third region is 80 to 40, and the luminance value of the fifth region is 20 to 10, but the microcomputer 17 In this case, the digital signal processing unit 14 operates to temporarily store the alternating captured video frames as described above, and then mixes them, so that the third region of the synthesized video frame may have a luminance level value. The maximum value is 100, and the luminance level value of the fifth area is 50.

Therefore, the luminance level difference value (for example, 50) of the third region and the fifth region of the synthesized video frame does not exceed 50, which is a preset reference value, so that a high luminance subject and a low luminance subject exist simultaneously. Since the image can be taken normally, and the shutter speed is adjusted to a multiple of 1 / 50th of the flicker removal, the flicker removal operation can be maintained.

For reference, the wide dynamic range operation may be applied to the above-described embodiments as well as various other embodiments, and in this case as well, the values of the long shutter speed and the short shutter speed are unique values set for flicker removal. (E.g. 1/50).

In addition, in order to remove the wide dynamic range and flicker, the jogging value of the shutter speed may be limited to only a common multiple of 50 and 60, and the above-described preferred embodiment of the present invention is disclosed for the purpose of illustration. As will be apparent to those of ordinary skill in the art, other various embodiments may be improved, changed, replaced, or added to within the spirit and scope of the present invention disclosed in the appended claims.

The wide dynamic range control method of the camera according to the present invention as described above uses a camera using an NTSC system of 60 Hz, for example, under a luminescent light such as a fluorescent lamp using an AC power source of 50 Hz. When performing a wide dynamic range (WDR) operation to shoot low-luminance subjects at the same time, the long shutter speed and the short shutter speed are set to eliminate flicker so that flicker does not occur. By variably adjusting the value (e.g., 1/50) to an integer multiple, it is a very useful invention that it is possible to normally remove the flicker phenomenon that the video screen is chewing even during the wide dynamic range operation.

Claims (7)

When performing a function of a wide dynamic range, checking a value of a preset flicker removal mode flag to detect whether a current operation mode is a flicker removal mode; And If the detection result of the flicker removal mode, by performing a wide dynamic range operation by variably adjusting to a long shutter speed and a short shutter speed, it comprises a step of variably adjusting the shutter speed in multiples of 1/50 seconds How to control the camera's wide dynamic range. The method of claim 1, In the first step, when the luminance level difference between the plurality of subjects existing in the captured image exceeds the reference value, the wide dynamic range function is performed, and the value of the preset flicker removal mode flag is checked. If the value is '1', the camera's wide dynamic range control method according to claim 1, wherein the current operation mode is detected by the flicker removal mode. delete The method of claim 1, If the detection result is not in the flicker removal mode, the method further comprises performing a wide dynamic range operation by variably adjusting the long shutter speed and the short shutter speed, and variably adjusting the shutter speed in multiples of 1/60 second. Characterized in a wide dynamic range control method of the camera. CD drive unit for changing the shutter speed of the CD; A light detector for dividing a video frame of a captured image into a plurality of regions and detecting a luminance level value of each divided region; And Comparing the luminance level value of each divided region, and comprises a microcomputer to perform a function of a wide dynamic range, When performing the function of the wide dynamic range, the microcomputer checks the value of the preset flicker removal mode flag to detect whether the current operation mode is the flicker removal mode, When the detection result is the flicker removal mode, the CD drive unit is operatively controlled to variably adjust the long shutter speed and the short shutter speed, but variably adjust the shutter speed in multiples of 1/50 second. The method of claim 5, And the micom checks a value of a preset flicker removal mode flag, and if the value is '1', detects the current operation mode as the flicker removal mode. The method of claim 5, If the microcomputer is not in the flicker removal mode as a result of the detection, the microcomputer operates and controls the CD drive unit to variably adjust the long shutter speed and the short shutter speed, but variably adjusts the shutter speed in multiples of 1/60 second. Camera.

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