That's a great idea. However, the following must be ensured: * The mip-mapped images can be purged manually. * The mip-mapped media files are removed if a software change affects how images are rendered, (e.g. if new metadata are considered) * Mip-mapped media files are updated if an image was overwritten; it is essentially important that *all* of them are updated. Inconsistencies here would cause a lot of confusion. * Currently, JPEG images are sharpened. Does this affect how the end-result looks like if they are sharpened twice? Do you expect other quality-issues, for example for GIF or PNG? Is there a comparison of applying down-scaling twice with doing it just once?
--Rillke