Figuring out a red channel workaround

doccutter

Well-known member
Well, I thought since a number of us are unhappy with the DVCPROHD codec's handling of bright reds, it would be useful to figure out a method using only FCP to clean up the red channel aliasing. It seems that one could use shake or AE, but I'd rather figure it out inside FCP. Unfortunately, my advanced effects skills are a bit rusty in FCP, so I thought maybe we could figure it out as a group. As I see it, it seems we need to follow several steps:

1)Drop problem clip on timeline
2)Make a copy of the problem clip, put on V2
3) On the V2 instance, we need to isolate the red channel
4) On the V2 clip, once it is isolated, put a guassian blur filter on
5) On v1 clip, drop out the red channel, leaving G and B
6) Key the V1 clip into the v2 clip, compositing so that red is taken from v2 and GB are taken from v1.

Any thoughts? Any better ways to do this? I've tried using the channel blur filter, but if you raise the level to a point where it is affecting the aliasing, the overall image turns to mush. What I'm trying to do is replicate what I've done with stills by sending them into photoshop and blurring the red channel. Anyone have any thoughts on this?
 
You want to do "Secondary Color Correction" which the APTS book "Advanced Color Correction and..." covers really well.

You can use the 3-Way Color Corrector filter to tone down only a specific shade of red without effecting anything else.
 
Well, to be fair, I'm not trying to tone down the red, I'm trying to blur the channel to offset the aliasing.
 
Hmmm... apply the blur in YUV space... mess around with U & V just don't touch the Y channel. I think there are a couple of plugins out there that let you do this... can't recall if Nattress or Joe's Filters can accomplish this.
 
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