Pixelization of Reds in 720p24n

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doccutter

Well-known member
Hey folks,

Pretty much since I've bought this camera 3 months ago, I've been shooting almost daily on a documentary in the Middle East. Well, now that I'm home and can look at the footage critically, I can see a few problems with the footage. The noise is there, but that's been hashed and rehashed, so I don't see any improvement happening there. What I'm wondering about is the fact that bright reds are consistently pixelated. I'm not sure if other folks have seen this problem. I can't seem to upload photos here, but I have some example jpegs if people are interested.
 
redpixelexample.jpg
 
Look at the red shirt around the wsu symbol, you can see a strange grid pattern. It happens on all saturated reds. The purple CA is also atrocious.
 
It's not CA. It's overexposure. The green CCD is blowing out to complete overexposure before the red and blue CCDs, so they're still delivering signal (and red + blue = purple).

If you see a purple fringe on one side, and a green fringe on the other, that's chromatic aberration.

If you see purple along the fringe of a blown-out overexposed shot, that's not CA, that's what happens when you overexpose. It also happens with a yellow tinge, frequently on clouds or something like that (when the blue blows out, but the red & green are still delivering signal, and R+G=yellow).
 
Ok, but what about the pixelization in the reds? It happens in any shots where there are bright, deep reds.
 
doccutter said:
Ok, but what about the pixelization in the reds? It happens in any shots where there are bright, deep reds.
Click to expand...
And it'll happen worse on an HD100 or FX1 or XLH1 too. It's color subsampling. The HVX uses 4:2:2, so bright saturated primary colors (red, blue, and green) get quantized into 2x1 pixel blocks.

Search around the boards, especially in the DV sections, and you'll see lots and lots of talk about this issue. Especially in DV where the reds and blues get lumped into 4x1 pixel blocks. On HDV they get lumped into 2x2 pixel blocks.
 
Ok, so it's a codec issue. Is there anyway to minimize it in post, can I smooth a color channel or something, or do I just have to live with it? It's also much more pronounced in the reds, bright greens and blues don't exhibit the same pattern.
 
Chroma bluuuuuuuuuurrrrrrrrrrr to the rescue. I'm beginning to think that there needs to be a chroma blur sticky topic, something like. . .

Got bad Reds? . . . Just apply a little chroma blur to the offending image and viola, like new. Please apply only as directed, not ment for internal ingestion.
 
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