Is colorized subpixel rendering possible?
Here's an example of a downsampling filter that takes pixel geometry into account: Increasing image resolution on portable displays by subpixel rendering.

Image (a) below is an image downsampled using pixel-based downsampling. Image (b) is downsampled using direct subpixel-based downsampling, which (as far as I can tell) effectively downsamples the R, G, and B planes of the image independently. Image (c) is downsampled using diagonal direct subpixel-based downsampling, which uses a diagonal pattern to improve apparent resolution in both horizontal and vertical directions.



You can see that the last two images look sharper, but also have the characteristic color fringing.

Here's the downsampling pattern used for the last image: