Imaging apparatus with dynamic range expanded, a video camera including the same, and a method of generating a dynamic range expanded video signal

Abstract

An imaging circuit generates 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 continues. The first video signal is synchronized with the second video signal. An exposure ratio between the first and second exposure intervals is detected. A gain of the second video signal is adjusted according to the exposure ratio. A combined video signal is generated from the first and second video signals according to a mixing control signal indicative of a mixing ratio between first and second video signals and levels of the first and second video signals to have an expanded dynamic range such that the first dynamic range is connected to the second dynamic range with difference in gains of the first and second video signals adjusted for linearity. An edge enhancement signal may be gain-controlled or coring-controlled according to the mixing control signal or the exposure ratio. The similar apparatus and method for color signals are also disclosed. The output dynamic range for a display is limited by a non-linear process.

What is claimed is:  
     
         1 . An imaging apparatus comprising: 
 imaging means including driving means 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, said second exposure interval being shorter than said first exposure interval, said first and second video signals respectively having first and second effective detection ranges which are different but continuous;    synchronizing means for synchronizing said first video signal with said second video signal every corresponding frames of said first and second video signals;    exposure interval ratio detection means responsive to said driving means for detecting an exposure ratio between said first and second exposure intervals;    gain adjusting means responsive to said first and second video signals from said synchronizing means for adjusting a difference between gains of said first and second video signals from said synchronizing means in accordance with said exposure ratio from said exposure interval ratio detection means;    mixing control signal generation means for generating a mixing control signal indicative of a mixing ratio of said first and second video signals in accordance with said first and second video signals from said gain adjusting means; and    combining means for generating and outputting a combined video signal from said first and second video signals from said gain adjusting means in accordance with said mixing control signal and levels of said first and second video signals to have an expanded detection range such that said first effective detection range is connected to said second effective detection range.    
     
     
         2 . A method of generating a combined video signal from an optical image comprising the steps of: 
 receiving said 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, said second exposure interval being shorter than said first exposure interval, said first and second video signals respectively having first and second effective detection ranges which are different but continuous;    synchronizing said first video signal with said second video signal every corresponding frames of said first and second video signals;    detecting an exposure ratio between said first and second exposure intervals;    adjusting a difference of gains of the synchronized first and second video signals in accordance with said exposure ratio;    generating a mixing control signal indicative of a mixing ratio of said first and second video signals in accordance with said gain-adjusted first and second video signals; and    generating and outputting said combined video signal from the gain-adjusted first and second video signals in accordance with said mixing control signal and levels of the gain-adjusted first and second video signals to have an expanded dynamic range such that said first effective detection range is connected to said second effective detection range.    
     
     
         3 . An imaging apparatus comprising: 
 imaging means including driving means 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, said second exposure interval being shorter than said first exposure interval, said first and second video signals respectively having first and second effective detection ranges which are different but continuous;    synchronizing means for synchronizing said first video signal with said second video signal every corresponding frames of said first and second video signals;    mixing control signal generation means for generating a mixing control signal indicative of a mixing ratio of said first and second video signals in accordance with said first and second video signals;    video signal generation means for generating a combined video signal from said first and second video signals from said synchronizing means in accordance with said mixing control signal and levels of said first and second video signals to have an expanded dynamic range such that said first effective detection range is connected to said second effective detection range;    edge enhancement signal generation means for generating an edge enhancement signal from said combined video signal;    edge enhancement amount control means for controlling an mount of said edge enhancement signal in accordance with said mixing control signal; and    adding means for adding said edge enhancement signal from said gain adjusting means and said combined video signal and outputting an edge-enhanced video signal.    
     
     
         4 . A method of generating a combined video signal from an optical image comprising the steps of: 
 receiving said 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, said second exposure interval being shorter than said first exposure interval, said first and second video signals respectively having first and second effective detection ranges which are different but continuous;    synchronizing said first video signal with said second video signal every corresponding frames of said first and second video signals;    generating a mixing control signal indicative of a mixing ratio of said first and second video signals in accordance with the synchronized first and second video signals;    generating said combined video signal from the synchronized first and second video signal in accordance with said mixing control signal and levels of said first and second video signals to have an expanded detection range such that said first effective detection range is connected to said second effective detection range;    generating an edge enhancement signal from said combined video signal;    controlling an amount of said edge enhancement signal in accordance with said mixing control signal; and    adding the amount-controlled edge enhancement signal and said combined video signal and outputting an edge-enhanced video signal.    
     
     
         5 . The imaging apparatus as claimed in  claim 3 , further comprising: 
 generation means generating a coring amount control signal in accordance with said mixing control signal; and    coring means for effecting a coring operation to the edge enhancement signal in accordance with said coring amount control signal.    
     
     
         6 . The method as claimed in  claim 4 , further comprising the steps of: 
 generating a coring amount control signal in accordance with said mixing control signal; and    effecting a coring operation to said edge enhancement signal in accordance with said coring amount control signal.    
     
     
         7 . An imaging apparatus comprising: 
 imaging means including driving means 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, said second exposure interval being shorter than said first exposure interval, said first and second video signals respectively having first and second effective detection ranges which are different but continuous;    synchronizing means for synchronizing said first video signal with said second video signal every corresponding frames of said first and second video signals;    exposure ratio detection means responsive to said imaging means for detecting an exposure ratio between said first and second exposure intervals;    mixing control signal generation means for generating a mixing control signal indicative of a mixing ratio of said first and second video signals in accordance with said first and second video signals;    combining means for generating a combined video signal from said first and second video signals from said synchronizing means in accordance with said mixing control signal and levels of said first and second video signals to have an expanded dynamic range such that said first effective detection range is connected to said second effective detection range;    edge enhancement signal generation means for generating an edge enhancement signal from said combined video signal;    edge enhancement amount control means for controlling an amount of said edge enhancement signal in accordance with said mixing control signal and said exposure interval ratio; and    adding means for adding said edge enhancement signal from said gain adjusting means and said combined video signal and outputting an edge-enhanced video signal.    
     
     
         8 . A method of generating a combined video signal from an optical image comprising the steps of: 
 receiving said 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, said second exposure interval being shorter than said first exposure interval, said first and second video signals respectively having first and second effective detection ranges which are different but continuous;    synchronizing said first video signal with said second video signal;    detecting an exposure ratio between said first and second exposure intervals;    adjusting a gain of said second video signal synchronized in accordance with said exposure ratio every corresponding frames of said first and second video signals;    generating a mixing control signal indicative of a mixing ratio of the synchronized first and second video signals in accordance with the gain-adjusted first and second video signals;    generating said combined video signal from the synchronized first and second video signals in accordance with said mixing control signal and levels of said first and second video signals to have an expanded detection range such that said first effective detection range is connected to said second effective detection range;    generating an edge enhancement signal from said combined video signal;    controlling an amount of said edge enhancement signal in accordance with said mixing control signal and said exposure ratio; and    adding the gain-adjusted enhancement signal from said gain adjusting means and said combined video signal and outputting an edge-enhanced video signal.    
     
     
         9 . The imaging apparatus as claimed in  claim 7 , further comprising: 
 coring amount control signal generation means for generating a coring amount control signal in accordance with said mixing control signal and said exposure ratio; and    coring means for effecting a coring operation to the edge enhanced signal in accordance with said coring amount control signal from said coring amount control signal generation means.    
     
     
         10 . The method as claimed in  claim 8 , further comprising the steps of: 
 generating a coring amount control signal in accordance with said mixing control signal and said exposure ratio; and    effecting a coring operation to the edge enhancement signal in accordance with said coring amount control signal.    
     
     
         11 . An imaging apparatus comprising: 
 imaging means including driving means for receiving separated red, green, and blue optical images and generating first red, first green, and first blue video signals with a first exposure interval and second red, second green, and second blue video signals with a second exposure interval substantially at the same time, said second exposure interval being shorter than said first exposure interval, said first red, green, and blue video signals respectively having first red, first green, and first blue effective detection ranges and said second red, green, and blue video signals respectively having second red, second green, and second blue effective detection ranges which are different from said first red, first green, and first blue effective detection ranges respectively but continuous;    synchronizing means for synchronizing said first red, first green, and first blue video signals with second red, second green, and second blue video signals every corresponding frames of said first red, first green, and first blue video signals and said second red, second green, and second blue video signals;    exposure interval ratio detection means responsive to said driving means for detecting an exposure ratio between said first and second exposure intervals;    gain adjusting means for respectively adjusting difference between gains of said first red, first green, and first blue video signals and second red, first, and video signals from said synchronizing means in accordance with said exposure ratio from said exposure interval ratio detection means;    mixing control signal generation means for generating red, green, and blue mixing control signals respectively indicating mixing ratios between said first red, first green, and first blue video signals and second red, second green, and second blue video signals in accordance with said first red, first green, and first blue video signals and second red, second green, and second blue video signals; and    combining means for generating and outputting combined red, green, and blue video signals from said first red, first green, and first blue video signals and second red, second, green, and second blue video signals from said gain adjusting means in accordance with said red, green, and blue mixing control signals and levels of said first red, first green, and first blue video signals and second red, second green, and second blue video signals to have expanded red, green, and blue detection ranges such that said first red, first green, and first blue effective detection ranges are connected to said second red, second green, and second blue video signals, respectively.    
     
     
         12 . The-imaging apparatus as claimed in  claim 11 , further comprising: 
 maximum detection means for detecting a maximum level among said combined red, combined green, and combined blue video signals for one frame period; and    non-linear processing means responsive to display dynamic range data for generating and outputting red, green, and blue display signals having non-linear characteristics such that said maximum level is made equal to or less than said display dynamic range data when the detected maximum level is larger than said display dynamic range data and outputting said combined red, green, and blue video signal as they are when the detected maximum level is not larger than said display dynamic range data.    
     
     
         13 . A method of generating a combined video signal from an optical image comprising the steps of: 
 receiving separated red, green, and blue optical images;    generating first red, first green, and first blue video signals with a first exposure interval and second red, second green, and second blue video signals with a second exposure interval substantially at the same time, said second exposure interval being shorter than said first exposure interval, said first video signals respectively having first red, first green, and first blue effective detection ranges, said second video signals respectively having second red, second green, and second blue effective detection ranges which are respectively different from first red, first green, and first blue effective detection ranges but continuous;    synchronizing said first red, first green, and first blue video signals with second red, second green, and second blue video signals every corresponding frames of said first red, first green, and first blue video signals and said second red, second green, and second blue video signals;    detecting an exposure ratio between said first and, second exposure intervals;    adjusting difference between gains of said first red, first green, and first blue video signals and second red, first, and video signals from said synchronizing means in accordance with said exposure ratio;    generating red, green, and blue mixing control signals respectively indicating mixing ratios between said first red, first green, and first blue video signals and second red, second green, and second blue video signals in accordance with said first red, first green, and first blue video signals and second red, second green, and second blue video signals; and    generating and outputting combined red, green, and blue video signals from said first red, first green, and first blue video signals and second red, second green, and second blue video signals from said gain adjusting means in accordance with said mixing control signals and levels of said first red, first green, and first blue video signals and second red, second green, and second blue video signals to have expanded red, green, and blue detection ranges such that said first red, first green, and first blue effective detection ranges are connected to said second red, second green, and second blue video signals, respectively.    
     
     
         14 . The method as claimed in  claim 13 , further comprising the steps of: 
 detecting a maximum level among said combined red, third green, and third blue video signals for one frame period; and    generating and outputting red, green, and blue display signals having non-linear characteristic in accordance with display dynamic data and said maximum level such that said maximum level is made equal to or less than said display dynamic range data when the detected maximum level is larger than said display dynamic range data and outputting said combined red, green, and blue video signal as they are when the detected maximum level is not larger than said display dynamic range data.    
     
     
         15 . A video camera comprising: 
 a lens unit;    separation means for separating an optical image beam into separated red, green, and blue optical images;    imaging means including driving means for receiving separated red, green, and blue optical images and generating first red, first green, and first blue video signals with a first exposure interval and second red, second green, and second blue video signals with a second exposure interval substantially at the same time, said second exposure interval being shorter than said first exposure interval, said first video signals respectively having first red, first green, and first blue effective detection ranges, said first and second video signals respectively having second red, second green, and second blue effective detection ranges which are different from said first red, first green, and first blue effective detection ranges but continuous;    synchronizing means for synchronizing said first red, first green, and first blue video signals with second red, second green, and second blue video signals every corresponding frames of said first red, first green, and first blue video signals and said second red, second green, and second blue video signals;    exposure interval ratio detection means responsive to said driving means for detecting an exposure ratio between said first and second exposure intervals;    gain adjusting means for adjusting difference between gains of said first red, first green, and first blue video signals and second red, first, and video signals from said synchronizing means in accordance with said exposure ratio from said exposure interval ratio detection means;    mixing control signal generation means for generating red, green, and blue mixing control signals respectively indicating mixing ratios between said first red, first green, and first blue video signals and second red, second green, and second blue video signals in accordance with said first red, first green, and first blue video signals and second red, second green, and second blue video signals; and    combining means for generating and outputting combined red, green, and blue video signals from said first red, first green, and first blue video signals and second red, second green, and second blue video signals from said gain adjusting means in accordance with said mixing control signals and levels of said first red, first green, and first blue video signals and second red, second green, and second blue video signals to have expanded red, green, and blue detection ranges such that said first red, first green, and first blue effective detection ranges are connected to said second red, second green, and second blue video signals, respectively.    
     
     
         16 . The camera as claimed in  claim 15 , further comprising: 
 maximum detection means for detecting a maximum level among said combined red, third green, and third blue video signals for one frame period; and    non-linear processing means responsive to display dynamic range data for generating and outputting red, green, and blue display signals having non-linear characteristic such that said maximum level is made equal to or less than said display dynamic range data when the detected maximum level is larger than said display dynamic range data and outputting said combined red, green, and blue video signal as they are when the detected maximum level is not larger than said display dynamic range data.    
     
     
         17 . The imaging apparatus as claimed in  claim 1 , wherein said gain adjusting means adjusts said difference between gains of said first and second video signals from said synchronizing means to provide a linearity in the expanded detection range.  
     
     
         18 . The imaging apparatus as claimed in  claim 1 , further comprising: 
 edge enhancement signal generation means for generating an edge enhancement signal from said combined video signal;    edge enhancement amount control means for controlling an amount of said edge enhancement signal in accordance with said mixing control signal; and    adding means for adding said edge enhancement signal from said gain adjusting means and said combined video signal and outputting an edge-enhanced video signal.    
     
     
         19 . The imaging apparatus as claimed in  claim 18 , wherein said edge enhancement amount control means controls said amount of said edge enhancement signal in accordance with said exposure ratio in addition to said mixing control signal.  
     
     
         20 . The imaging apparatus as claimed in  claim 1 , further comprising: 
 edge enhancement signal generation means for generating an edge enhancement signal from said combined video signal;    coring amount control signal generation means for generating a coring amount control signal in accordance with said mixing control signal;    coring means for effecting a coring operation to the edge enhanced signal in accordance with said coring amount control signal from said coring amount control signal generation means; and    adding means for adding said edge enhancement signal from said edge enhancement signal generation means and said combined video signal and outputting an edge-enhanced video signal.    
     
     
         21 . The imaging apparatus as claimed in  claim 20 , wherein said coring amount control signal generation means generates said coring amount control signal in accordance with said exposure ratio in addition to said mixing control signal.