| 摘要 |
<p>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).</p> |
