Interesting. If you're worried about correctness I'd just do integration testing. Get a bunch of raw files from different manufacturers and test them with rawspeed on the desktop and on the browser, comparing output. If it's performance though it seems strange when there are 3D engines being ported to asm.js that something like rawspeed wouldn't optimize well.
The alternative seems a little crazy to me. Reimplementing a full raw library in JS is a huge task. I've just spent a total of 6-7 hours getting the basics of MRW support in rawspeed and those formats are just insane, and change continuously between models of the same manufacturer. And even within a single model you'll get crazy variations depending on camera settings.
AFAIK these 3D-engines was specially prepared to be ported to JS. We have abit another specific than just moving 3D objects, creating scenes and blend textures.
Sure, its very similar, but our "textures" is bigger and we should know about more than one pixel per time to do correct demosaic process. Its not the same to create cool WebGL 3D effect and do JPG decompression for example.
The alternative seems a little crazy to me. Reimplementing a full raw library in JS is a huge task. I've just spent a total of 6-7 hours getting the basics of MRW support in rawspeed and those formats are just insane, and change continuously between models of the same manufacturer. And even within a single model you'll get crazy variations depending on camera settings.
Best of luck.