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help using chroma key on uneven screen?
I am fairly new to using the chroma key, but unfortunately I’ve started out with a tough case. The blue screen I’m trying to key out has a few wrinkles causing saturated white lighting in spots and also the blue light intensity becomes darker as the flood lighting was not as even as desired. I’ve tried standard instructions like here
https://digitalproducer.digitalmedianet.com/articles/viewarticle.jsp?id=31596
which can get somewhat close, but I am left with screen reminants especially where the original blue screen became darker. It’s almost as if I need two separate keys, but not sure if that’s the correct approach.Any help would be appreciated here.
Thanks,
Jon -
9 Replies
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If you can post a sample clip or screen grab that would be helpful.
However, you can mask out the portion of the screen that is giving you the problem and key it separately (or just place your replacement media on that track and let it show through. If your talent is often coming in and out of that portion of the screen, you will have a more difficult task. I assume you have used chroma blur? Another option (free) is to use the trial version of NewBlueFX’s ChromaKeyer to see if it can do a better job for you. And yet another free option is Cinegob’s keyer. They may or may not get you the desired results but they can be worth the try. That’s about as good as advice as I can give you until you post a screenshot or sample clip.
j razz
https://www.jrazzcreations.com
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Hey Jon,
I just acquired a green screen, although I haven’t tried it yet, it came with an educational DVD, which I have watched.
They do stress the importance of lighting in BS or GS. They demo it using two 500 W lights, with softboxes aimed at the screen in a criss-cross manner. they claim that once you do this, (with no wrinkles in your screen), you can then add a key light on your subject.
I hope this helps.
Gilles
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Jeremy Rasnic said:
“However, you can mask out the portion of the screen that is giving you the problem and key it separately…”
That would be ideal as the portion that still needs keyed out does not conflict with the subject. How would I go about it? Thanks, Jon
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Click on the pan/crop icon on the event that has the blue screen. On the keyframe timeline on the pan/crop window there are two modes- the bottom one is for masking. If you select this the masking tools will show up on the left hand column. Simply “cut” out the portion that is giving you problems. (notice there is a positive/negative dropdown- this affects which part shows through. Either the part you cut will show up or everything but the part you cut will show up)
Make sure your replacement background is on the track below that one.
j razz
https://www.jrazzcreations.com
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A little off topic
But in the
https://digitalproducer.digitalmedianet.com/articles/viewarticle.jsp?id=31596-0
article they draw out a rectangle with the eye dropper and it does not do that in my sv9.Pentium 2.4 quad|Asus P5G41C-M LX mobo|2 gig corsairs 6400 ram|Corsairs 630 power supply|Gigabyte 8800gt|2x seagate 500gig Hd’s|Lg dvd burner|windows7 premium , SV9E
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“…they draw out a rectangle with the eye dropper and it does not do that in my sv9.”
This was another useful feature that got changed in the newest release.
Lots of us complained loud and long to Sony but to no avail 🙁
The rectangle is still there but no longer shows up when dragging.
Go ahead and draw it out like you normally would, making sure to stay within a good sample area. -
Thanks. This sort of works, but I find it awkward. I’m fairly new to Vegas, so perhaps that’s the reason. What I think would be easiest for me is to create two separate compositions, each with different keyframed portions, and then layer the two compositions and erase sections of the top layer leaving the composition underneath. I don’t know if there’s a way to do this in Vegas 9. In After Effects, I would simply create two “pre-comps” and then use the “eraser tool” to erase the top layer leaving the bottom. Does Vegas 9 have an eraser tool and can I create the equivalent of precomps?
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It’s almost as if I need two separate keys, but not sure if that’s the correct approach.
One way to fix this is by using the Color Corrector (Secondary). The secondary color corrector allows you to change the color of parts of a video. What you do is add the secondary color corrector before the Chroma Keyer and set it to only affect the dark blue, and change it to match the light blue. Add it again if needed to smooth out the color of the screen until it is just one color. Then chroma key that.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
Hey thanks guys, I wasn’t really happy with my chroma keying results, I will try this next time.
Pentium 2.4 quad|Asus P5G41C-M LX mobo|2 gig corsairs 6400 ram|Corsairs 630 power supply|Gigabyte 8800gt|2x seagate 500gig Hd’s|Lg dvd burner|windows7 premium , SV9E
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