Does anyone know what hq4x does to the Doom picture? I'd be interested in comparing edge-cases like that, especially as it seems hq4x would handle it decently well, while this algorithm does pretty poorly. Understandably so, but I wonder if it can be adapted to handle broader blending forms.
However, this algorithm does actually vectorize the image, which has interesting uses for e.g. running all the sprites of a game through it and using the static results in a remake (they also talk about extending it to fill in animation frames in time which would be extra cool).
It doesn't look good, as there's not enough high-contrast edges for hqx to work.
Ref: http://en.wikipedia.org/wiki/Pixel_art_scaling_algorithms
hmmm. wikipedia turns up many http://en.wikipedia.org/wiki/Comparison_of_raster_to_vector_... but the one i was thinking of was potrace - http://potrace.sourceforge.net/
i've used potrace many times before - it works really well (i once hand-wrote some "powerpoint" slides, scanned them, then used potrace to make them appear "natural" - people thought i had made a font based on my handwriting!)
maybe it's the handling of colour that's new here? potrace only does monochrome images, as far as i know.
... If this really works as well as it seems, it's going to ruin some of our best pop-culture-technology jokes.