EP0278175A1
Expired / Lapsed
EP
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Image processing
Assignee: Crosfield Electronics Ltd
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Filing: 1987-12-21
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Granted: —
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Expires: 2007-12-21
Abstract
Abstract Apparatus for modifying part of an image represented digitally in the frequency domain comprises a first memory (29) for storing a representation of the image digitally in the frequency domain as at least one first block of data locations containing frequency coefficient data. A second memory (30) is provided for storing a representation of the image part in the frequency domain by second blocks of data locations containing frequency coefficient data, the first and second blocks representing, after conversion to the spacial domain, spatially shifted versions of the image part relative to a fixed spatial co-ordinate system. A suitably programmed computer (31) applies a predetermined shift function defined in the frequency domain to the or each first block of data stored in the first memory (29) to generate the or each second block, and stores the resultant second blocks of data in the second memory (30).
Inventors
- 👤 Peter William Stansfield
- 👤 Alastair Reed
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 13:24
CPC Classifications
G; G06; G06T; G06T3/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
151 words
A method of modifying part of an image represented digitally in the frequency domain by at least one first block of data locations containing frequency coefficient data in which for each first block a second block of data locations containing frequency coefficient data is generated, the first and second blocks representing, after conversion to the spatial domain, spatially shifted versions of the image part relative to a fixed spatial coordinate system, the method comprising applying a predetermined shift function defined in the frequency domain to the or each first block of data locations to generate the or each second block of data locations. 2. A method according to claim 1, wherein the image part is defined by an orthogonal array of first blocks of data locations, the step of applying a shift function comprising applying a single one dimensional shift function one or more times in each of the orthogonal directions.
Claim 2
Dependent Claim
18 words
A method according to claim 2, wherein the inverse transform of the shift function comprises a delta function.
Claim 3
Independent Claim
127 words
A method according to any of the preceding claims, the method comprising a) applying the predetermined shift function to each first block of data locations to generate modified blocks in which the content of each data location is modified; b) determining the data locations in the modified first blocks which contribute to the content of each second block of data locations; and c) for each said second block which does not define an edge of the shifted image summing the coefficients of each frequency as defined by the content of those data locations of the modified first blocks which are determined to contribute to said second block to generate resultant coefficients for each frequency, and storing the resultant coefficients in respective data locations of the second block.
Claim 4
Independent Claim
16 words
A method according to any of the preceding claims, wherein the first blocks have identical dimensions.
Claim 5
Dependent Claim
147 words
Apparatus for modifying part of an image represented digitally in the frequency domain, the apparatus comprising a first memory (29) for storing a representation of the image digitally in the frequency domain as at least one first block of data locations containing frequency coefficient data; a second memory (30) for storing a representation of the image part in the frequency domain by second blocks of data locations containing frequency coefficient data, the first and second blocks representing, after conversion to the spatial domain, spatially shifted versions of the image part relative to a fixed spatial coordinate system; and processing means (31) for applying a predetermined shift function defined in the frequency domain to the or each first block of data stored in the first memory (29) to generate the or each second block, and for storing the resultant second blocks of data in the second memory (30)
Claim 6
Dependent Claim
147 words
Apparatus for modifying part of an image represented digitally in the frequency domain, the apparatus comprising a first memory (29) for storing a representation of the image digitally in the frequency domain as at least one first block of data locations containing frequency coefficient data; a second memory (30) for storing a representation of the image part in the frequency domain by second blocks of data locations containing frequency coefficient data, the first and second blocks representing, after conversion to the spatial domain, spatially shifted versions of the image part relative to a fixed spatial coordinate system; and processing means (31) for applying a predetermined shift function defined in the frequency domain to the or each first block of data stored in the first memory (29) to generate the or each second block, and for storing the resultant second blocks of data in the second memory (30)
Claim 7
Dependent Claim
14 words
Apparatus according to claim 6, wherein the processing means (31) comprises a programmed computer.
Claim 8
Dependent Claim
19 words
A computer programmed to carry out the steps of a method according to any of claims 1 to 5.
References Cited (Backward Citations)
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