EP0350328A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Offset, gain and bad pixel correction in electronic scanning arrays
Assignee: Xerox Corp
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Filing: 1989-07-07
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Granted: —
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Expires: 2009-07-07
Abstract
Abstract Method and apparatus for a wide range of correction of photosite offset and gain. Each photosite is provided with a correction value for offset and gain based on measured light intensity value. Each photosite correction value is also provided with an attribute value which is detected by a decoder (208) and indicates (i) whether the correction values are to be used as stored (in a memory 200); (ii) whether a shift of the values (by shift means 210 a , 210 b ) is appropriate, in accordance with a shift value stored in a shift memory (212); or (iii) whether the photosite is non-correctable, and accordingly requires the implementation by an output selector (214) of a bad pixel routine comprising the substitution of an approximated photosite response derived at a bad pixel correction device (218).
Inventors
- 👤 Ying-Wei Lin
- 👤 Anthony F. Calarco
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 20:02
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/409; H04N1/401; H04N25/00; H04N25/60; H04N25/67; H04N25/671; H04N25/673; H04N25/68; H04N25/70; H04N25/701
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
128 words
An image scanning device having a scanning array with a plurality of photosites detecting light from an image, each photosite producing a response indicative of light intensity, and including means for correction of responsivity of the photosites, said means (100) comprising: a memory (200) storing correction values for photosites along the array, said correction values including a correction portion and an attribute value; means (204, 206) to apply said correction portion to the photosite response; a decoder (208) for detecting said attribute value; shift means (210 a , 210 b ) for shifting said correction portion prior to application to the photosite response by a selected number of places, said shift means being responsive to detection by said decoder of an attribute value indicating that shifting should occur.
Claim 2
Dependent Claim
128 words
An image scanning device having a scanning array with a plurality of photosites detecting light from an image, each photosite producing a response indicative of light intensity, and including means for correction of responsivity of the photosites, said means (100) comprising: a memory (200) storing correction values for photosites along the array, said correction values including a correction portion and an attribute value; means (204, 206) to apply said correction portion to the photosite response; a decoder (208) for detecting said attribute value; shift means (210 a , 210 b ) for shifting said correction portion prior to application to the photosite response by a selected number of places, said shift means being responsive to detection by said decoder of an attribute value indicating that shifting should occur.
Claim 3
Dependent Claim
93 words
A device as defined in claim 1, wherein: the correction portion of said correction values includes an offset correction and a gain correction; the means for applying said correction portion comprises offset correcting means (204) for correcting the offset of photosite response in accordance with the stored offset corrections and gain correcting means (206) for correcting the gain of the photosite response in accordance with the stored gain corrections; and the shift means is operable to shift said offset correction and said gain correction prior to the application thereof to said photosite response.
Claim 4
Dependent Claim
43 words
A device as defined in claim 1 or claim 2, wherein said attribute value is one of a limited number of different values (m x , n x ), each different value indicating a different shift to be applied to said shift means.
Claim 5
Dependent Claim
28 words
A device as defined in claim 3, including a shift memory (212) for storing the shift function indicated by the attribute values, for use by said shift means.
Claim 6
Independent Claim
28 words
A device as defined in any one of the preceding claims, and including means (214) for substituting an approximated response for an actual response from a particular photosite.
Claim 7
Dependent Claim
40 words
A device as defined in claim 5, wherein said means for substituting an approximated response for an actual response from a particular photosite is responsive to detection by said decoder of an attribute value indicating that said substitution should occur.
Claim 8
Independent Claim
48 words
A device as defined in any one of the preceding claims, wherein said correction value is a multi bit binary value, including a first number of bits for gain correction, a second number of bits for offset correction and a third number of bits for the attribute value.
Claim 9
Dependent Claim
32 words
A device as defined in claim 7, wherein said third number of bits for the attribute value is equal to two bits, providing a total of four choices for the attribute value.
Claim 10
Dependent Claim
68 words
A device as defined in claim 8, wherein for the possible choices for the attribute value, a first value indicates that the gain and offset values should be shifted by 0 places, second and third values indicate that said gain and offset correction should be shifted selected numbers of places respectively, and a fourth value indicates that an approximated photosite response should be substituted for the photosite response.
Claim 11
Independent Claim
103 words
A method of correcting the responsivity of photosites in an image scanning device having a scanning array with a plurality of photosites detecting light from an image, each photosite producing a response indicative of light intensity, said method comprising the steps of: storing correction values for correction of photosite response in a memory; providing each said correction value with an attribute value; for each photosite response to be corrected, sensing said attribute value; applying a predetermined shift function to said correction value responsive to said attribute value to derive a new correction value; and applying said new correction value to said photosite response.
Claim 12
Independent Claim
103 words
A method of correcting the responsivity of photosites in an image scanning device having a scanning array with a plurality of photosites detecting light from an image, each photosite producing a response indicative of light intensity, said method comprising the steps of: storing correction values for correction of photosite response in a memory; providing each said correction value with an attribute value; for each photosite response to be corrected, sensing said attribute value; applying a predetermined shift function to said correction value responsive to said attribute value to derive a new correction value; and applying said new correction value to said photosite response.
Claim 13
Independent Claim
145 words
A method of correcting the responsivity of photosites in an image scanning device having a scanning array with a plurality of photosites detecting light from an image, each photosite producing a response indicative of light intensity, said method comprising: for each photosite correctable to a normalized value, storing a correction value in a correction memory to be applied to the photosite response for correction thereof; for each photosite not correctable to a normalized value, storing a distinctive value in said correction memory indicating that an approximated photosite response should be substituted for an actual photosite response; detecting said distinctive value and enabling a photosite approximation function to produce an approximated response; applying said correction value to said photosite response to correct said response to a normalized value; substitution an approximated response for the actual response for each photosite response not correctable to a normalized value.
Claim 14
Independent Claim
145 words
A method of correcting the responsivity of photosites in an image scanning device having a scanning array with a plurality of photosites detecting light from an image, each photosite producing a response indicative of light intensity, said method comprising: for each photosite correctable to a normalized value, storing a correction value in a correction memory to be applied to the photosite response for correction thereof; for each photosite not correctable to a normalized value, storing a distinctive value in said correction memory indicating that an approximated photosite response should be substituted for an actual photosite response; detecting said distinctive value and enabling a photosite approximation function to produce an approximated response; applying said correction value to said photosite response to correct said response to a normalized value; substitution an approximated response for the actual response for each photosite response not correctable to a normalized value.
References Cited (Backward Citations)
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