Resolume Forum

Hi, I’m having an issue where the effectiveness of chroma key is changing and I can’t figure out why or how to stabilize it, can you please help?

The effectiveness of chroma key seems to be changing based on whether I have a guitar in my hands, even when the guitar is cropped out of the shot. I don’t understand why holding a guitar would change the effectiveness of the chroma key- the color of the green screen (and the lighting and settings in the chroma key effect) remain the same whether i am holding the guitar or not. But I noticed that a perfect chroma key that made the green screen completely invisible is always showing parts of the green screen when i pick the guitar up, then it returns to being perfect when i put the guitar down.

If I move the Key Hue a little bit while i hold the guitar in my hands, then I can make the chroma key perfect once again while the guitar is in my hands, but then the same problem just occurs in reverse- the chroma key will be messed up whenever i put the guitar down (unless i tweak the Key Hue again).
I also tried cropping out the guitar from the shot fully so that the frame of the output looked the same whether i was holding the guitar or not holding the guitar (all you saw was my face and upper body), and it still had the same issue with chroma key.

Why is this happening and how can i fix it?

I want to make it so that the chroma key just works well when i have the guitar in my hands or not, without having to change Key Hue setting every time. Video and pics below:



https://www.youtube.com/watch?v=mTVWy52LJOw



holding guitar (bottom is cropped out)

https://www.dropbox.com/s/sbdvlwpidm92j ... 2.png?dl=0


not holding guitar (bottom is cropped out)

https://www.dropbox.com/s/7xhez9l98dxv7 ... 1.png?dl=0


holding guitar, chroma key is off, (bottom is cropped out)

https://www.dropbox.com/s/giuil2f6x3cug ... 1.png?dl=0


not holding guitar, chroma key is off, (bottom is cropped out)

https://www.dropbox.com/s/dilpsuoisb0uk ... s.png?dl=0

When you pick up the guitar, the light reflections of it bounce on your green screen.
The easiest fix would be to increase the hue threshold in the Chroma Key.

Green screen needs a very uniform lighting to work well - that's why you see the shadows flicker in it -, and some distance, so it also doesn't bounce the green light back to you. Distance would also help keep minimizing the light that bounces from the guitar to the screen.

Another tip would be not wearing green/blue in front of a green screen