I chose the MSX1 Screen 2 filter, as it looked quite similar to the ZX Spectrum filter. I'd never actually seen an MSX computer working (I saw some switched off in a shop once) so I didn't really know what to expect until I read up on Wikipedia.
Whereas the ZX Spectrum suffered from attribute clash on the character square level, MSX1 suffered from attribute clash on the character row level so I was expecting the resulting images to look like slightly better ZX Spectrum images. And so it turned out.
To compare, here is John Liven's photograph of a cottage:
Cottage - Photo: John Livens
And here it is processed by the ZX Spectrum filter:
Cottage - ZX Spectrum
And finally by the MSX1 filter:
Cottage - MSX1
Converting the filter was straightforward, and I managed to find and fix a small bug in the sdlBasic original whilst I was going along.
As always, the finished MSX1 filter can be downloaded from here.