| 摘要 |
Descriptions of phantom raster scan are generated with high spatial resolution in angular coordinates and in coordinates, such as radial coordinates, orthogonal to the angular coordinates. The more significant bits of these coordinates are used to generate read addresses for a relatively low spatial resolution image memory supplying, in parallel, four data at a time descriptive of spatially adjacent points in image space. The less significant bits of one of these coordinates are used in calculating first and second linear interpolations between pairs of these data, and the less significant bits of the other of these coordinates are used in calculating a third linear interpolation between the results of the earlier linear interpolations to obtain successive samples of a video signal descriptive of the image stored in image memory. This avoids the need for large-capacity ROM in making the interpolations among image memory data to avoid rastering effects in the display.
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