how much does Pro Res Proxy degrade image quality?

Transcoding from 7D H.264 footage, some Go Pro .mp4 and some weird Sony .mts files.
I don't see much image degradation. Bit rates are comparable. What's really going on in that transcode process? How much would I be sacrificing not going back to the raw, and re-transcoding to Pro Res for the finished piece? All I need to do is some light color correcting and effects.
Thanks,
-Alex-

He's Asking about prores proxy. I notice a decent quality loss, even when converting from gopro...

Oh...Proxy. that's an offline codec...not meant as final. Quality really isn't important at that point, as you won't be using it for the final. I cannot give you exactness in how quality degrades, but it is grainy.

But then you never should use the orignal GoPro or Canon DSLR files for finishing either. They are HIGHLY compressed, and not suited to editing nor finishing.

I've worked on shows that mixed XDCAM and GoPro and Canon 5D...we transcoded all to ProRes proxy for offline cut, then brought in everything as ProRes 422 for finish.

Proxy is an offline quality codec.

Shane
Little Frog Post
Read my blog, Little Frog in High Def

I have never seen anyone make that comparison.

Shane
Little Frog Post
Read my blog, Little Frog in High Def