JPH03220878A - Automatic exposure correcter - Google Patents

Abstract

PURPOSE:To obtain a picture signal output with a proper exposure in real time by providing a specified value taking a mean luminance around a center of a picture as a reference with respect to any part of the picture so as to apply automatic filtering thereby correcting the exposure. CONSTITUTION:An analog picture signal from a photodetector 7 is inputted also to a luminance decision section 1 and A/D conversion is applied to the analog picture signal for each picture element unit, the signal is converted into a digital picture data and a high luminance picture element over the specified value of surrounding picture elements is detected and decided by taking the mean luminance around the center of the picture as a reference. The luminance decision section 1 outputs a position data of a high luminance picture element to an LCD control section 2 as a control signal for filtering operation of an LCD 3. That is, the LCD 3 is used to apply filtering to and mask the high luminance part at the specified level or over at the surrounding with respect to the luminance around the center of the optical picture input while the optical picture input at rear light is used as an object.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic exposure compensation device, and more particularly to an automatic exposure compensation device that automatically provides appropriate exposure for a received light input in an optical device.

[Conventional technology]

Conventionally, this type of exposure compensation device is as shown in FIG.
The optical image input from the outside through the lens 4 is separated by the polarizing prism 5, the average brightness of the separated optical image input is detected by the brightness detection section 8, and the diaphragm mechanism 6 is controlled based on the result to detect the light receiving element 7. , receive light and compensate for exposure.
It was configured to obtain an image signal output.

[Problem to be solved by the invention]

The conventional exposure compensation device shown in FIG. 3 described above inputs an external optical image separated by a polarizing prism 5 as it is to a brightness detection unit 8, and controls an aperture device [6] according to the average brightness. Because of this configuration, when there is a large difference in brightness depending on the position of the external optical image input, for example in a backlit situation, the image of the desired subject will be underexposed and become completely black.

In addition, in order to prevent the above-mentioned underexposure state, it is necessary to manually set the exposure using the human visual sense for the brightness detection unit 8, which inevitably leads to setting errors and takes time to set. The drawback is that it is not possible to respond in a timely manner.

[Means to solve the problem]

The automatic exposure compensation device of the present invention is an automatic exposure compensation device that obtains an image signal output by applying proper exposure to an optical image input received through a lens, and the center of the image for each pixel that forms the bottom of the image signal output. a brightness determination unit that determines high-brightness pixels that exceed a specified value based on nearby average brightness and outputs their position data; and a brightness determination unit that corresponds to the position data of the high-brightness pixels with respect to the optical image input that determines exposure. The LCD is configured to include an LCD capable of applying filtering to a region, and an LCD control section that controls to drive a filtering operation for the high brightness pixels of the LCD based on position data output from the brightness determination section. Ru.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the automatic exposure compensation device of the present invention, and FIG. 2 is an explanatory diagram showing an example of LCD operation in response to external light image input in the embodiment of FIG. 1. In FIG. 1, the parts indicated by bold lines are directly related to the present invention, and the other parts have the same content as in FIG. 3.

An optical image input from the outside is input to the polarizing prism 5 through the lens 4. The polarizing prism 5 outputs an image signal to an aperture mechanism 6, and also spectrally outputs an optical image input to the LCD 3 for exposure control.

The image signal separated by the diaphragm mechanism 6 is received by a light receiving element (CCD) 7 using a CCD to obtain an image signal output. In this embodiment, the analog image signal from the light receiving element 7 is also input to the brightness determination section 1, and the brightness determination section 1
After converting this analog image signal into digital image data by performing A-D conversion on a pixel-by-pixel basis, high-luminance pixels that are higher than the specified value of surrounding pixels are detected and judged based on the average luminance near the center of the image. . The brightness determination unit 1 outputs the position data of this high brightness pixel to the LCD control unit 2 as a control signal for filtering operation of the LCD 3.

The LCD control unit 2 drives the LCD 3 based on the position data from the brightness determination unit 1 so as to perform a filtering operation (mask) on an area of the LCD 3 corresponding to the area specified by the position data. The LCD 3 is installed between the polarizing prism 5 and the brightness detection section 8, and operates to filter the exposure light image input from the polarizing prism 5.

FIG. 2 is an explanatory diagram of the filtering operation of the LCD 3 in the embodiment of FIG. 1. FIG. 2 shows the optical image input 10 in a backlit state, and the brightness around the center of the optical image input 10 is compared to the peripheral high luminance area exceeding the specified value and the LCD 3.
, and the shaded portion of the LCD 3 filtering area is masked by filtering.

The brightness detection unit 8 uses an aperture mechanism 6 to provide appropriate exposure for the necessary subject 13 near the center of the image even in a backlit situation.
can be controlled to obtain an image signal output 12 under proper exposure.

〔Effect of the invention〕

As explained above, the present invention sets a predetermined value based on the average brightness near the center of the image for any part of the image, and automatically applies filtering to perform exposure compensation, thereby adapting to human settings. The effect is that image signal output with appropriate exposure can be obtained in real time regardless of the exposure.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the automatic exposure compensation device of the present invention, FIG. 2 is an explanatory diagram showing an example of LCD operation in response to external light image input in the embodiment of FIG. 1, and FIG. FIG. 2 is a block diagram of an exposure compensation device. 1... Brightness determination section, 2... LCD control section, 3...
LCD, 4... Lens, 5... Polarizing prism, 6.
... Aperture bridge, 7... Light receiving element, 8... Brightness detection section.

Claims (1)

[Claims] In an automatic exposure compensation device that obtains an image signal output that applies appropriate exposure to a light image input received through a lens, a specified value based on the average brightness near the center of the image for each pixel that makes up the image signal output. a brightness determination unit that determines high-intensity pixels that exceed 100% and outputs their position data; and an LCD capable of filtering an area corresponding to the position data of the high-intensity pixels with respect to the optical image input that determines exposure. (Liquid Crystal Dis
an automatic exposure compensation device, comprising: an LCD controller configured to drive a filtering operation for the high-intensity pixels of the LCD based on position data output from the brightness determination unit; .