Color adjustments before chroma keying

[oklava]

Hi,
I have a green screen shot which is taken as s-log video.

I have to push the values because green background has slight reflection on skin.

If I increase saturation and contrast exaggeratedly before keylight, would it improve keying?

[Dave_LaRonde]

This is known as spill suppression.  There is a spill suppressor built into keylight, and there is a newer stand-alone spill suppressor in AE.

Since we don't have a picture to see, we can't comment on any color adjustments with any confidence.

[oklava]

byroncortez​
Thanks a lot both of you for reply,
But doesn't spill suppressor effect "after" the keylight?
I just thought maybe it would be better for keylight if we seperate colors more with contrast and saturation before selecting screen color.

By the way I tried this today but somehow keyed edges deteriorated.

[Dave Merchant · Accepted solution]

Yes, spill suppression happens after (or as part of) keying.

If the key itself isn't working very well (AE's inbuilt keyers are not the best on the market) then the normal workaround is to create a separate mask:

1. Duplicate the layer containing the footage.
2. Adjust the colors of the top layer (contrast, curves, etc) so it's extreme and will key more easily, even though it looks awful.
3. Apply the keyer to the top layer only, and adjust to get clean edges - ignoring things like spill. Often easiest to switch the keyer to the B&W alpha/mask view for this.
4. Hide the top layer, then set the bottom - untouched - layer to use the top layer's alpha channel as a mask.

[oklava]

Thank you,
So which keyer do you recommend?
Also I read about using two layers (top one has keylight + key cleaner, bottom one has only spill supressor and alpha matte) works better than using them in one layer even if you don't use color adjusting.

[Dave Merchant]

Keying with multiple layers has always been the solution for footage which is beyond the limited abilities of the keying software. It harks back to the very origins of matte keying, where physical film was masked with a specially processed copy. Splitting the processing into layers can get better results, but if the footage is awful then it's hardly ever going to come out perfect unless you spend weeks rotoscoping every frame. 99% of keying is about capturing the best footage, on the best camera, with the best lighting; and 1% is about complaining when the footage is awful.

There's no "recommended" keyer for every situation; which works best depends entirely on the footage, and some of the best are only available in one product. While Keylight is technically a third party tool, the suite of key and spill effects bundled with AE is only available in AE, and things like the new Delta keyer are only available in Fusion. Independent products like Primatte will work in most editors, though being more expensive doesn't make something better. Since most have a free trial, the most sensible thing to do is take advantage of that and see for yourself which you prefer.

[oklava]

My footage is pretty good ( it is taken with sony fs7 with proper lighting )
The only downside is; green background is normal green fabric and it doesn't has the best color for keying. A slight reflection on skin causes a bit chattering.

But I am close to a satisfying result right now. I should work a little more.
Thanks a lot

[Byron Cortez]