Television – Camera – system and detail – Optics
Reexamination Certificate
1997-04-10
2001-02-13
Garber, Wendy (Department: 2712)
Television
Camera, system and detail
Optics
C348S364000, C348S229100
Reexamination Certificate
active
06188434
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for automatically controlling a quantity of light received in an image pickup device.
An image pickup device should provide a proper light exposure so as to obtain an image with a relatively high or excellent quality. Such image pickup device may sense a signal level of a picked-up image and automatically control an iris diaphragm of the image pickup device in accordance with the sensed signal level. However, in sensing or detecting such signal level, the image pickup device may sense the signal level of the entire or overall image which may include the background thereof. As a result, the aperture value of the color image pickup device is influenced by such sensed signal level. As such, the signal level due to the picked-up background image may obstruct or adversely affect the proper aperture value for a desired target object. In other words, the brightness of the background may hinder obtaining a proper brightness condition for the target object. For example, a target object may be made shadowed in a backlighted condition, and subject to halation in an excessively lighted condition.
Further, to provide a correct exposure, the image pickup device may perform automatic iris control which changes an interior divisional ratio of a peak value to an average luminance level of an overall screen for shifting a target value to a bright or a dark side. Such control may produce an adverse effect on the aperture value of a highly luminous portion however long the area may be. Moreover, the difference between the peak value and the average luminance level may be relatively small and may result in a disadvantageous restriction in the amount of shifting.
Furthermore, as previously described, the image pickup device may perform iris control for the overall screen. As such, the image pickup device may not provide a proper aperture value for a specific area of the screen.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to provide an apparatus and method for controlling the light exposure of a color image pickup device so as to provide a proper brightness of a target object independently of the brightness of the background so as to produce an image having a relatively high quality.
Another object of the present invention is to provide an apparatus and method as aforesaid which provides a plurality of modes for controlling light exposure in which a control exposure mode may be selected in accordance with an imaging condition so as to produce a relatively high quality image.
In accordance with an aspect of the present invention, a color image pick-up apparatus is provided which comprises an image pick-up unit having a device for receiving light representative of an image, a device for converting light into a number of light signals, and a device for controlling the amount of the light which is to be converted into the light signals in accordance with a control signal; a processing device for processing the light signals in a predetermined manner; and a control signal generating device including a luminance converter and a plurality of determining devices for receiving the processed light signals and for generating the control signal therefrom.
The present color image pickup device may include a control device and a level sensing unit having a number of level sensing devices such as a first level sensing device and a second level sensing device. The first level sensing device operates to sense a signal level of an area of a specific luminance level specified by a first area generating device and contained in a luminance signal supplied from a luminance converting device (which converts a color imaging signal obtained by a color image pickup unit to the luminance signal). The second level sensing device operates to sense a signal level of a skin tone area specified by a second area generating device and contained in the luminance signal supplied from the luminance converting device. The control device operates to control the quantity of light received in the color image pickup unit so that the sensed output or first average signal level obtained by the first level sensing device, the sensed output or second average signal level obtained by the second level sensing device or a middle signal level between the first average signal level and the second average signal level is set at a predetermined level. The control device may further operate to adjust an interior divisional point between the first average signal level and the second average signal level to the middle signal level and an area ratio of the area of the specific luminance level to the skin tone area to an interior divisional ratio.
Other objects, features and advantages according to the present invention will become apparent from the following detailed description of illustrated embodiments when read in connection with the accompanying drawings in which corresponding components are identified by the same reference numerals.
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Patent Abstracts of Japan, vol. 015, No. 375 (E-1114), Sep. 20, 1991 & JP 03 148987 A (Minolta Camera Co Ltd), Jun. 25, 1991.
Frommer William S.
Frommer Lawrence & Haug LLP.
Garber Wendy
Nguyen Luong
Smid Dennis M.
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