Patent US6061092A successfully refreshed from Google Patents.
US6061092A
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Method and apparatus for dark frame cancellation for CMOS sensor-based tethered video peripherals
Assignee: Intel Corp
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Filing: 1997-12-05
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Granted: 2000-05-09
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Expires: 2017-12-05
Abstract
Abstract Elimination of dark fixed pattern noise (DFPN) for tethered CMOS sensor-based digital video cameras is supported by supplying and maintaining a host-based dark image cache. Since the camera is tethered to a host computer system such as a PC, it takes advantage of the storage and processing capabilities of the host to manage the cache. By using a dark image cache for updating of the currently applicable dark image for DFPN cancellation processing, operation of the camera shutter for acquiring dark images is dramatically reduced, thereby using less system resources such as power, and increasing the MTBF of the electromechanical devices such as the camera shutter and associated controls. Dark images are obtained at different integration, gain, and temperature operating characteristics of the camera and stored in the cache. The cached dark images are referenced on the host according to a fixed, predetermined dark column of data in video frames generated by the CMOS sensor image array of the camera. The dark column data represents a portion of the CMOS sensor image array which is permanently and totally shadowed for use during DFPN cancellation processing.
Inventors
- 👤 Ashutosh J. Bakhle
- 👤 Bradley C. Aldrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:19
CPC Classifications
H; H04; H04N; H04N25/00; H04N25/60; H04N25/67; H04N25/671; H04N23/00; H04N23/60; H04N23/80; H04N23/81; H04N25/63; H04N25/633; H04N25/70; H04N25/76
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
210 words
A method of selecting dark images used in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising: providing a cache of dark images, the dark images being indexed by a data structure, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; obtaining current dark image reference data from at least one dark area in a current frame of a stream of frames generated by the digital imaging system, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; comparing the current dark image reference data obtained from the dark area of the current frame to at least one entry in the data structure of dark image reference data; and using a dark image from the cache associated with an entry in the data structure of dark image reference data to perform dark fixed pattern noise cancellation processing on the stream of frames when the current dark image reference data corresponds to the entry.
Claim 2
Independent Claim
210 words
A method of selecting dark images used in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising: providing a cache of dark images, the dark images being indexed by a data structure, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; obtaining current dark image reference data from at least one dark area in a current frame of a stream of frames generated by the digital imaging system, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; comparing the current dark image reference data obtained from the dark area of the current frame to at least one entry in the data structure of dark image reference data; and using a dark image from the cache associated with an entry in the data structure of dark image reference data to perform dark fixed pattern noise cancellation processing on the stream of frames when the current dark image reference data corresponds to the entry.
Claim 3
Dependent Claim
29 words
The method of claim 1 wherein the cache is stored on a host computer system and the imaging system is a video camera coupled to the host computer system.
Claim 4
Dependent Claim
20 words
The method of claim 2, further comprising downloading the dark image from the host computer system to the video camera.
Claim 5
Dependent Claim
23 words
The method of claim 2, further comprising sending the current dark image reference data from the video camera to the host computer system.
Claim 6
Dependent Claim
14 words
The method of claim 1, further comprising enabling generation of the stream of frames.
Claim 7
Dependent Claim
42 words
The method of claim 1, wherein the comparing step further comprises comparing the current dark image reference data to at least one entry in the data structure of dark image reference data only when operating characteristics of the CMOS sensor have changed.
Claim 8
Dependent Claim
46 words
The method of claim 1, wherein the comparing step further comprises comparing the current dark image reference data to entries in the data structure of dark image reference data only when the current dark image reference data is different than immediately preceding dark image reference data.
Claim 9
Dependent Claim
29 words
The method of claim 7, wherein the difference between the current dark image reference data and the immediately preceding dark image reference data is greater than a threshold amount.
Claim 10
Dependent Claim
101 words
The method of claim 1, wherein the providing step comprises: acquiring a new dark image from the CMOS sensor; storing the new dark image in the cache; and updating the data structure of dark image reference data by adding a new entry associated with the new dark image, the new entry containing dark image reference data associated with the new dark image; wherein the acquiring, storing, and updating are performed when the current dark image reference data signifying the current operating characteristics of the CMOS sensor does not correspond with any entries in the data structure of dark image reference data.
Claim 11
Dependent Claim
21 words
The method of claim 9, further comprising transferring the new dark image from the imaging system to a host computer system.
Claim 12
Dependent Claim
26 words
The method of claim 9, further comprising deleting an existing dark image in the cache before storing the new dark image when the cache is full.
Claim 13
Independent Claim
179 words
An apparatus for selecting and using dark images in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising: a cache of dark images, the cache comprising a data structure indexing the dark images, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; means for obtaining current dark image reference data from at least one dark area in a current frame of a stream of frames captured by the digital imaging system, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; and means for performing dark fixed pattern noise cancellation processing on the current frame using a selected dark image from the cache associated with an entry in the data structure when the current dark image reference data corresponds to the entry.
Claim 14
Independent Claim
179 words
An apparatus for selecting and using dark images in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising: a cache of dark images, the cache comprising a data structure indexing the dark images, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; means for obtaining current dark image reference data from at least one dark area in a current frame of a stream of frames captured by the digital imaging system, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; and means for performing dark fixed pattern noise cancellation processing on the current frame using a selected dark image from the cache associated with an entry in the data structure when the current dark image reference data corresponds to the entry.
Claim 15
Dependent Claim
16 words
The apparatus of claim 12, further comprising means for enabling generation of a stream of frames.
Claim 16
Dependent Claim
37 words
The apparatus of claim 12, wherein the cache is stored on a host computer system and the obtaining means and the performing means are components of a CMOS sensor-based video camera coupled to the host computer system.
Claim 17
Dependent Claim
19 words
The apparatus of claim 14, further comprising a bi-directional interface coupling the video camera to the host computer system.
Claim 18
Dependent Claim
16 words
The apparatus of claim 15, wherein the bi-directional interface is a universal serial bus (USB) interface.
Claim 19
Dependent Claim
39 words
The apparatus of claim 15, wherein the video camera comprises a memory for storing a current dark image used in dark fixed pattern noise cancellation processing and the selected dark image is transferred from the cache to the memory.
Claim 20
Dependent Claim
27 words
The apparatus of claim 15, wherein the current dark image reference data is transferred from the obtaining means on the video camera to the host computer system.
Claim 21
Dependent Claim
34 words
The apparatus of claim 18, wherein the host computer system comprises means for comparing the current dark image reference data to entries in the data structure of dark image reference data in the cache.
Claim 22
Dependent Claim
32 words
The apparatus of claim 19, wherein the comparing means compares the current dark image reference data to entries in the data structure only when operating characteristics of the CMOS sensor have changed.
Claim 23
Dependent Claim
39 words
The apparatus of claim 19, wherein the comparing means compares the current dark image reference data to entries in the data structure only when the current dark image reference data is different than immediately preceding dark image reference data.
Claim 24
Dependent Claim
29 words
The apparatus of claim 21, wherein the difference between the current dark image reference data and the immediately preceding dark image reference data is greater than a threshold amount.
Claim 25
Independent Claim
196 words
An apparatus for selecting and using dark images in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising: a CMOS sensor having at least one dark area, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; a cache of dark images, the cache comprising a data structure indexing the dark images, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; a processing unit to obtain current dark image reference data from the at least one dark area in a current frame of a stream of frames captured by the digital imaging system; a dark fixed pattern noise subtraction unit to perform dark fixed pattern noise cancellation processing on the current frame using a selected dark image from the cache associated with an entry in the data structure when the current dark image reference data corresponds to the entry.
Claim 26
Independent Claim
196 words
An apparatus for selecting and using dark images in dark fixed pattern noise cancellation processing in a CMOS sensor-based, digital imaging system based on current operating characteristics of the CMOS sensor comprising: a CMOS sensor having at least one dark area, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; a cache of dark images, the cache comprising a data structure indexing the dark images, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; a processing unit to obtain current dark image reference data from the at least one dark area in a current frame of a stream of frames captured by the digital imaging system; a dark fixed pattern noise subtraction unit to perform dark fixed pattern noise cancellation processing on the current frame using a selected dark image from the cache associated with an entry in the data structure when the current dark image reference data corresponds to the entry.
Claim 27
Dependent Claim
37 words
The apparatus of claim 23, further comprising a memory for storing a current dark image used in dark fixed pattern noise cancellation processing and wherein the selected dark image is transferred from the cache to the memory.
Claim 28
Dependent Claim
45 words
The apparatus of claim 23, wherein the cache is stored on a host computer system and the processing unit and the dark fixed pattern noise subtraction unit are components of a CMOS sensor-based video camera coupled to the host computer system by a bi-directional interface.
Claim 29
Dependent Claim
16 words
The apparatus of claim 25, wherein the bi-directional interface is a universal serial bus (USB) interface.
Claim 30
Dependent Claim
194 words
A machine readable medium having stored therein a plurality of machine readable instructions designed to be executed by a processor, the machine readable instructions for providing a cache of dark images, the dark images being indexed by a data structure, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; obtaining current dark image reference data from at least one dark area in a current frame of a stream of frames generated by a CMOS sensor-based digital imaging system, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; comparing the current dark image reference data to entries in the data structure of dark image reference data; and using a dark image from the cache associated with an entry in the data structure of dark image reference data to perform dark fixed pattern noise cancellation processing on the stream of frames when the current dark image reference data corresponds to the entry.
Claim 31
Dependent Claim
194 words
A machine readable medium having stored therein a plurality of machine readable instructions designed to be executed by a processor, the machine readable instructions for providing a cache of dark images, the dark images being indexed by a data structure, each entry in the data structure storing dark image reference data associated with one of the dark images, each dark image corresponding to a set of operating characteristics of the CMOS sensor; obtaining current dark image reference data from at least one dark area in a current frame of a stream of frames generated by a CMOS sensor-based digital imaging system, the at least one dark area being a portion of the CMOS sensor receiving no illumination and operating as a signature of the current operating characteristics of the CMOS sensor; comparing the current dark image reference data to entries in the data structure of dark image reference data; and using a dark image from the cache associated with an entry in the data structure of dark image reference data to perform dark fixed pattern noise cancellation processing on the stream of frames when the current dark image reference data corresponds to the entry.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-05-09 | 2003-11-08 | 2004-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-05-09 | 2007-11-08 | 2008-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-05-09 | 2011-11-08 | 2012-05-09 | $7700.00 | Window Closed / Lapsed |