Pink artifacts at hard contrast junctions

NeedCreative

NeedCreative

Well-known member
Hello all. I was going back and forth with a few people on Twitter last night about some nasty artifacting I am seeing with the FS100 - a pink chromatic aberration-style fringe on white highlights. This happens on every lens, even nice high priced Zeiss glass. Here's an example where it was particularly horrible - this is a white LED strip in a ceiling (here shown in about a 300x blow up):
led pink.jpg

I thought for sure in this instance I was seeing aliasing as well as the perils of the internal 4:2:0 codec. But then I've seen it fully in the frame on other shots. Example:here, on the sparkles off of water:
pink water.jpg

Another close up, not as bad:
sparkles.jpg

And yes, it shows clearly in motion as well.

My friend James who has an Atomos Ninja tested this for me as well and the issue is even sharper on that, so it's not the internal codec.

Someone suggested that perhaps a knee setting or "flare" setting that can be applied in a picture profile (of which there is none in the Sony) might work as it does on a Panasonic camera (he didn't give me the model). Anyone have any ideas how to combat this? I was running off PP5 in the ceiling case with some minor tweaks based on Frank's settings posted here.
 
I ran into this issue as well. At the time, I did not have time to play around with the knee settings. I was getting it on some fluorescent lights in a factory, and with street lights.

Taken at 100%
o06y4z.png
 
Yep that's it. Some friends think if the Knee is modified this can go away but I am not at all sure how to do that (as far as what setting will work without wrecking the rest of the picture)
 
I don´t have the camera here in the moment, but can you guys try to provoke the problem and than set the knee slope to zero (no mater what other setting or knee you use) and see if it goes away?
This is just a wild guess, but from what I learned over the last weeks, it may be a remedy.

Frank
 
use the histogram to see where you are clipping the highlights, and adjust stops to avoid clipping the highlights...

i have the some footage here from shows i have graded shot with Si2K, RED/MX F3, & Arri Alexa camera's that show the same thing... best advice i have is - don't do it.

There's not a whole lot i can do in the finishing suite to save that either, i'd rather dig noise out of the shadows and kill that with noise reduction than i would replace pink fringed skys...

d/
 
That's the thing, no clipping was shown on the histogram (at least in the ceiling shot). I'm careful to avoid that...

Edit: I did some experiments just pointing the camera at a LED recessed light fixture. I used a slope of 0 and a knee point of 90 and 95. The lower the knee of course the worse things are. I also went with a color level of -4.

Those settings seem to help. But Dermot is correct - the only thing that seems to fix the problem for sure is minimizing to almost nothing anything that goes over to the right; in my case a zebra line of about 95. If there's a little line on the histogram that spikes at the 100 range or so - that's the pink fringing/halo. In some shots it can be hard to get rid of entirely, but with proper exposure and a lowered color setting and slope of zero, that helps.

I'm just wondering if the AF100 has this as bad. I can tell you that my Canon 60D doesn't do it all, no matter how blown out the highlight is. There's literally zero color fringing, even using the same lens. (at 6400 ISO at F1.4 just to test, intentionally overexposing the light similarly to the FS100.

Here are some examples:

(I know the focus is a little off here but you get the idea)

60D - 2500 ISO, F2.8:

60D fringe.jpg

FS100 - PP6 tweaked with a 95 manual knee and 0 slope, 0 db, F2.8:

FS100 fringe - blown.jpg

These examples aren't great due to the compression. So here's a look at them plus a moire shot here: http://gallery.me.com/pantico#100641&view=grid&bgcolor=black&sel=5
 
Last edited:
Postmaster said:
I don´t have the camera here in the moment, but can you guys try to provoke the problem and than set the knee slope to zero (no mater what other setting or knee you use) and see if it goes away?
This is just a wild guess, but from what I learned over the last weeks, it may be a remedy.

Frank
Click to expand...

Just checked Frank; it's set at zero.
 
A few more examples, likely overexposure (and before I changed PP and added +5 to slope)- look at glint on top of planes:

More Pink.jpgpink on plane.jpg
 
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