Video appears brighter after H.264. export

It's difficult to say without more information,
like the codec that iShowU is using, for example.
However, FCP changes the displayed gamma in certain cases,
which can make the image look brighter or darker down the line.

Try inserting the filter Image Control > Gamma Correction
on your footage in FCP. Can you recreate the washed-out look
by adjusting the gamma to a value larger than 1?
If so, that indicates that a gamma change is happening.

One quick'n'dirty way to deal with the problem would be to apple
the inverse function. So if your washed-out effect looks like
a gamma boost of 1.5, then try applying the inverse gamma (1/1.5),
which would be .67 .

How are you exporting to H.264? Via QT Conversion or via Compressor. Either way you will pick up a slight gamma shift, and H.264 is not the best codec for preserving color accuracy, but using Compressor will yield better results.

Hi,
are you previewing your videos in Quicktime player?
If so, there is a setting in versions 7.5.5+ that corrects the gamma...

I long suspected this to be related to Quicktime player, since other players did not display the same symptoms. And all of a sudden, there was this gamma correction option under "preferences"...hmmm 🙂

Edv!n

This a known issue with Apple's implementation of the H.264 codec, but you can fix the problem by downloading x264encoder. This thread will give you more details:

http://discussions.apple.com/thread.jspa?threadID=1358418&start=0&tstart=0