rvio h264 colors 16-235?

Hello:
  When converting some images to a libx264 movie, it looks like some colorspace shifting is happening.  I'm losing a lot of detail in the darks and it looks like perhaps rv is using a 16-235 instead of 0-255 range for the colors?  Doing a:

rvio ./clean.101-193@@@.jpg -codec libx264 -o rvio_264.mov

looks a lot darker than a somewhat equivalent ffmpeg call:

ffmpeg -r 24 -start_number 101 -f image2 -i ./clean.%d.jpg -vframes 93 -vcodec libx264 -pix_fmt yuv420p ffmpeg_264.mp4

Is there a flag I can send to the outparams of rvio to emulate what ffmpeg is doing?

Thank you!
jake