text - render - excess luma?

Posted by howard 
text - render - excess luma?
April 23, 2011 06:28PM
Hi, on FCP 6 color correction. I color correct, everything is under 100 then I add text, everything looks good on the waveform monitor, then I render and it cancels the color correction, (goes from 95 to 105 before my eyes).

Yes when I go broadcast safe it fixes it but I?ve seen a number of people report this e.g. ?Rob Weaver Color Correction:Broadcast Safe - Render Bug?? I haven?t found a forum discussion with a fix.

Is there a fix?

Cheers, Howard
Re: text - render - excess luma?
April 23, 2011 08:05PM
Try the RGB limit plug in. It's another way of doing broadcast safe.


Re: text - render - excess luma?
April 23, 2011 09:13PM
Hi Harry, thanks that works. I must say I?m still inquisitive as to why, when I render, I lose my color correction. Eg if I put text on v2 for half my clip, I can see the scopes return to my settings the instant the playhead goes past the text. Or I can watch the RGB parade pop back to where they were before I corrected once the render is completed, if the playhead is over the text as well as the clip. Curious.

Is the RGB filter like the broadcast safe, insofar as you should use it after you?ve finished the job and use it last?
Cheers, Howard
Re: text - render - excess luma?
April 23, 2011 10:56PM
Is the text itself broadcast safe? You need the whites at about 225 to be safe. The broadcast safe filter you are applying to the clip, not the text. So if this is not safe, then the frame of course will no longer be safe.

Re: text - render - excess luma?
April 24, 2011 06:24AM
Okay, this gets more mysterious, for me at least. I?ve been working on a 3 minute section of a 60 min program. Cut and paste from the program onto new sequence for tweaking color correction before deciding on my final. Everything is under 100, nothing over saturated in the original. All green ticks.

Once I?ve pasted into new sequence (a sequence with exactly the same setting), I render this section, everything on V1, under text on V2, is now showing excess luma. Even though in the original was not.

Yes, I?ve done a few experiments; applied broadcast safe to both and separately, doesn?t work if I just do it to text but otherwise it works. But if analysed on scopes, both clip and text are within broadcast limits without needing filters.

Yellow triangles and exclamation marks. I know how that icon feels.
Re: text - render - excess luma?
April 24, 2011 10:04AM
The excess luma shows on the side of caution, so it triggers off at 100 IRE, the green stripes come on at 90%. Default FCP text at 8 bit Rgb 255,255,255, is mapped to 100 IRE and is safe for broadcast, unless your station requires less than 100 IRE for maximum luma.

The RGB safe limits your image to within RGB safe, so your colors are "legal" in this sense. There are differences to what is broadcast legal, so you should get the specs from your station if you are doing the final touches on the project.

Re: text - render - excess luma?
April 24, 2011 09:32PM
And check for flicker on your broadcast monitor. That's the big teller on whites.

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