Methods and apparatus for displaying images, e.g., text characters, on
display devices which have multiple separately controllable luminance
elements per pixel. 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. 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. 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.