![]() Key what you can and then compress the key a little further and use a dechatter effect to help out (if needed). And most of that lost info is going to be the subtle stuff that you need to separate the hair from the green screen.īut not all cameras shoot uncompressed (or have interchangeable lenses) sooo. ![]() That’s a factor of about 70! That’s a huge amount of information that has been lost. If you are using H264 you are, at best, probably running around 20 mega bits per second. HD (in 8bit) is 186 mega bytes per second. But in a green screen scenario you should have more than enough light to work with.Īlways key with as uncompressed footage as you can. I will concede a faster lens can help the noise problem out a little: when a CCD doesn’t have enough light work with it injects voltage in to the chip and you get more noise – a gopro camera does a beautiful job in full sun but looks noisy noisy noisy at night. It could also be noise from the camera’s chip. This is probably caused by the compression of the footage either in the camera or when it was compressed after the camera (to make it a manageable file size to send). ![]() That shimmer you are seeing is digital noise. The saturation of the color and the differences between the screen color and everything else are what’s important, not the actual color itself. But these days you can key off any color. You will notice gaps where information, (color information) is now missing and the smooth transitions from one color to another are now steppy.īack in the optical days we had to hit a specific color of screen to make the chemical process of the film work. Any time you color correct something you are throwing information away. Uneven is uneven and opening up your fstop (in other words: a faster lens) will make the dark spots brighter but will also make the bright spots even brighter and the lighting will still be uneven.Ĭolor correcting the screen color (punching it up) before keying is also a no-no. I’m not sure how a “fast” lens will help with uneven lighting. So the solution is to use low compression & a fast lens, however, I still believe that I managed to produce good keying in the past without either of these & I don’t understand why. If I captured footage with a slow lens then it still had the shimmer issue. This did help considerably, in fact I did manage to overcome most of the shimmering, but only when I used it in conjunction with a very fast lense. Capture footage directly & use 4:2:2 format. It’s strange, because I’m sure that I’ve achieved a perfect key with these cameras before, but on other threads it was suggested that compression will cause issues especially with DSLR cameras. So the next possibility was the camera & compression. We even covered the floor & all excess green with blacks.Ħ. The mannequin was 4 metres from the green screen & it still showed no improvement. Too close to the green screen or caused by reflective spill. Too much or too little foreground light.Īgain this made no difference after much testing.Ĥ. No matter what I did with the backlight, it made little difference….even no back light at all.ģ. This also helped a bit, but increased the rendering time enormously.Ģ. Possible solution B- I added a denoise effect before the Primatte keying. Although it did have some effect, it wasn’t significant enough. Possible solution A- I tried using zero gain and more light. Most of the time I had to use gain as high as 9dBs I actually struggled to get enough light even with 14 fluros & 4 foreground lights. ![]() The Nex VG20 has a big sensor which is supposed to compensate for the slow lens & poor low light. I suspected that it may be due to the amount of gain needed for the cameras. – foreground – 1200 LEDs (had to use a red head & softbox for added light) – warmĬameras – Sony Nex VG20 DSLRs using AVCHD & direct capture 4:2:2 & motion jpegġ. Lighting – greenscreen – fluros (both horizontal & vertical around a 5m screen) – daylight Admittedly, this has had no work done on it (one press Primatte), but even after I spent hours trying to eliminate the shimmer…I couldn’t reduce it completely via After Effects.Įditing: After Effects with Primatte plugin SAMPLE: Here’s a rough sample of what I’m talking about. I just spent several days trying isolate the problem with some results. The most troublesome issue was the shimmering effect I kept getting at the top of the hair & around the upper edges. THE PROBLEM: I used to do a lot of green screen shooting & editing & it all seemed to work easily, but recently I did a job & I had tremendous problems.
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