Television – Camera – system and detail – Optics
Reexamination Certificate
1998-11-06
2003-07-15
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Optics
C348S222100, C348S229100, C348S086000
Reexamination Certificate
active
06593970
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an imaging apparatus with its dynamic range expanded, a video camera including the same, and a method of generating a dynamic range expanded video signal.
2. Description of the Prior Art
An imaging apparatus for generating a dynamic range expanded video signal by combining video signals generated substantially at the same time with different exposure intervals is known. Such an image apparatus is disclosed in Japanese patent application provisional publication No. 07131718A. A video signal processing circuit including an edge enhancement signal generation circuit generating an edge enhancement signal from a video signal and a gamma correction circuit for compensating a gamma of the video signal, wherein the edge enhancement signal is not subjected the gamma correction and is added to the gamma-corrected video signal is known. Such a video signal processing circuit is disclosed in Japanese patent application provisional publication No. 63-209373.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a superior imaging apparatus with dynamic range expanded, a superior video camera including the same, and a superior method of generating a dynamic range expanded video signal.
According to the present invention, a first imaging apparatus is provided, which comprises: an imager including driving circuit for receiving an optical image and generating a first video signal with a first exposure interval and a second video signal with a second exposure interval substantially at the same time, the second exposure interval being shorter than the first exposure interval, the first and second video signals respectively having first and second effective detection ranges which are different but continuous; a synchronizing circuit for synchronizing the first video signal with the second video signal every corresponding frames of the first and second video signals; an exposure interval ratio detection circuit responsive to the driving circuit for detecting an exposure ratio between the first and second exposure intervals; a gain adjusting circuit responsive to the first and second video signals from the synchronizing circuit for adjusting a difference between gains of the first and second video signals from the synchronizing circuit in accordance with the exposure ratio from the exposure interval ratio detection circuit for linearity; a mixing control signal generation circuit for generating a mixing control signal indicative of a mixing ratio of the first and second video signals in accordance with the first and second video signals from the gain adjusting circuit; and a combining circuit for generating and outputting a combined video signal from the first and second video signals from the gain adjusting circuit in accordance with the mixing control signal and levels of the first and second video signals to have an expanded detection range such that the first effective detection range is connected to the second effective detection range.
In the first imaging apparatus, the gain adjusting circuit adjusts the difference between gains of the first and second video signals from the synchronizing circuit to provide a linearity in the expanded detection range.
The first imaging apparatus may further comprise: an edge enhancement signal generation circuit for generating an edge enhancement signal from the combined video signal; an edge enhancement amount control circuit for controlling an amount of the edge enhancement signal in accordance with the mixing control signal; and an adding circuit for adding the edge enhancement signal from the gain adjusting circuit and the combined video signal and outputting an edge-enhanced video signal. In this case, the edge enhancement amount control circuit controls the amount of the edge enhancement signal in accordance with the exposure ratio in addition to the mixing control signal.
The first imaging apparatus may further comprise: an edge enhancement signal generation circuit for generating an edge enhancement signal from the combined video signal; a coring amount control signal generation circuit for generating a coring amount control signal in accordance with the mixing control signal; and a coring circuit for effecting a coring operation to the edge enhanced signal in accordance with the coring amount control signal from the coring amount control signal generation circuit; and an adding circuit for adding the edge enhancement signal from the edge enhancement signal generation circuit and the combined video signal and outputting an edge-enhanced video signal. In this case, the coring amount control signal generation circuit generates the coring amount control signal in accordance with the exposure ratio in addition to the mixing control signal.
According to the present invention, a first method of generating a combined video signal from an optical image is provided which comprises the steps of: receiving the optical image and generating a first video signal with a first exposure interval and a second video signal with a second exposure interval substantially at the same time, the second exposure interval being shorter than the first exposure interval, the first and second video signals respectively having first and second effective detection ranges which are different but continuous; synchronizing the first video signal with the second video signal every corresponding frames of the first and second video signals; detecting an exposure ratio between the first and second exposure intervals; adjusting a difference in gains of the synchronized first and second video signal in accordance with the exposure ratio; generating a mixing control signal indicative of a mixing ratio of the first and second video signals in accordance with the gain-adjusted first and second video signals; and generating and outputting the combined video signal from the gain-adjusted first and second video signals in accordance with the mixing control signal and levels of the gain-adjusted first and second video signals to have an expanded dynamic range such that the first effective detection range is connected to the second effective detection range.
According to the present invention, a second imaging apparatus is provided which comprises: an imager including a driving circuit for receiving an optical image and generating a first video signal with a first exposure interval and a second video signal with a second exposure interval substantially at the same time, the second exposure interval being shorter than the first exposure interval, the first and second video signals respectively having first and second dynamic ranges which are different but continuous; a synchronizing circuit for synchronizing the first video signal with the second video signal every corresponding frames of the first and second video signals; a mixing control signal generation circuit for generating a mixing control signal indicative of a mixing ratio of the first and second video signals; a video signal generation circuit for generating a combined video signal from the first and second video signals from the synchronizing circuit in accordance with the mixing control signal and levels of the first and second video signals to have an expanded dynamic range such that the first effective detection range is connected to the second effective detection range; an edge enhancement signal generation circuit for generating an edge enhancement signal from the combined video signal; an edge enhancement amount control circuit responsive to the driving circuit for controlling an amount of the edge enhancement signal in accordance with the mixing control signal; and an adding circuit for adding the edge enhancement signal from the gain adjusting circuit and the combined video signal and outputting an edge-enhanced video signal.
The second imaging apparatus may further comprise a generation circuit generating a coring amount control signal in accordance with the mixing control signal and a coring circuit for effecting a coring operati
Serizawa Masayuki
Tabei Kenji
Connolly Bove & Lodge & Hutz LLP
Garber Wendy R.
Ye Lin
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