I have a project captured in DV420.   If I decompose the sequence and bring it back in at 1:1 mxf am I getting a higher resolution?   I was under the impression that dv420 was compressed.

thanks

You won't gain any quality by coming back in at 1:1. But all EFX & titles should be rendered at 1:1 for best quality.

What format is the original footage? If it is anything better than dv then yes you'll get better quality by coming back in at 1:1. If it's dv footage anyway then there's minor benefits to capturing at 1:1 if you plan to color correct.

siencs:

...there's minor benefits to capturing at 1:1 if you plan to color correct.

Yes true. I assumed you had DV sources. Original DV sources won't improve quality by capturing at 1:1, but if you do capture them at 1:1, color correction and multiple renders will hold up better.

If you have already captured your footage at DV resolution (4:2:0) then coming back to 1:1 mxf from captured DV 4:2:0 will not help, as Frosty said.

If your source material is DV 4:2:0, and you brought it into Avid via a firewire connection then you did the right thing by capturing your footage at its native resolution as Avid will not change/transcode your DV source to anything else at capture if brought in via a firewire connection (and Avid will simply re-wrap it, people of knowledge please correct me if I am wrong here).

If your source footage is in a format other then DV, however, then digitizing it at 1:1 mxf or 1:1x (for 10 bit) would be the best option for maintaining your source footage's original quality (whatever it maybe).  And as Frosty mentioned, you would want to set your render settings to 1:1(x) as well.

"....benefits to capturing at 1:1 if you plan to color correct."

Interesting Siencs, didn't think of it this way as I always have wanted to leave my original DV originated footage untouched thru capture process until the time came for any fx or correction etc.