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oklava
oklava
Known Participant
June 19, 2019
Answered

Color adjustments before chroma keying

  • June 19, 2019
  • 2 replies
  • 1049 views

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?

This topic has been closed for replies.
Correct answer Dave Merchant

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.

2 replies

B
Community Expert
Byron CortezCommunity Expert
Community Expert
June 20, 2019

Byron.
Dave_LaRonde
Dave_LaRonde
Inspiring
June 19, 2019

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
oklavaAuthor
Known Participant
June 20, 2019

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.

D
Dave MerchantCorrect answer
Legend
June 20, 2019

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.
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