| 摘要 |
Methods and apparatus for displaying images, e.g., text characters, on display devices which have multiple separately controllable luminance elements per pixel are described. Multiple alpha values are generated per pixel, e.g., one per pixel sub-component. Filtering is then performed to generate a filtered alpha value for each pixel sub-component. The filtering operation uses as its input multiple alpha values, e.g., 5 per pixel. The alpha values used for the filtering operation may come from neighboring pixels. Accordingly, in the case where character glyphs are combined to form larger images, e.g., text strings, the filtering operation performed on glyph edge pixels depends on the content of a neighboring character glyph. In one embodiment unfiltered alpha values used to represent character glyphs are stored in a glyph cache. After caching, the unfiltered alpha values from multiple glyphs are combined and then the filtering operation is performed. To avoid repeated filtering of character glyphs, in another embodiment, character glyphs are padded along their vertical edges, filtered and then stored in the glyph cache. Glyphs are output from the cache as required and then combined with filtered alpha values corresponding to overlapping image portions being summed. As a result of the summing processes, correct filtered alpha values are generated along glyph edges for the combined image corresponding to multiple glyphs.
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