Oh really? Is this using the Scale2x algorithm too? If so, it would save me a step. It looks like it isn't, which is why I applied it after generating. Scale2x is great for upscaling pixel art in a power of 2 size to a power of 2 size 1 greater (like 32x32 to 64x64), as it never adds colors and tries to preserve details.
Sorry, didn't realise you were using an algorithm to upscale! This looks really good, going to have a play with some sprites myself. Will look at the possibility of integrating this or something similar in future versions. Thanks again and keep up the good work.