Question / Help Help me understand chroma key!

[Voodin]

I've been experimenting with chroma key, but Im not close to a wall to put up a big poster, so ive been experimenting with cloth. BUT, I've found a dark green blanket and when I set chroma to that color, the bright white objects in my room get filtered out also, why?then I tried a green book http://prntscr.com/3tx61h , http://prntscr.com/3tx66f here is the comparison of chroma on and off

 

[Lain]

The "similarity" setting is probably too high, 400+ feels quite high, causing it to bleed off in to other colors.

Chroma key ideal for filtering out colors specifically within real world video capture and images. The most ideal way to set up chroma key is to have a brightly lit (and not shiny) backdrop of a very pronounced color, particularly green or blue. Having that backdrop well lit also helps. Ideally, you want the "similarly" value to be as low as possible, yet just high enough to create the effect, to prevent it from sampling other parts of the picture.

 

[Voodin]

The "similarity" setting is probably too high, 400+ feels quite high, causing it to bleed off in to other colors.

Chroma key ideal for filtering out colors specifically within real world video capture and images. The most ideal way to set up chroma key is to have a brightly lit (and not shiny) backdrop of a very pronounced color, particularly green or blue. Having that backdrop well lit also helps. Ideally, you want the "similarly" value to be as low as possible, yet just high enough to create the effect, to prevent it from sampling other parts of the picture.

The odd thing is ive tried similarity as low as 40 and still had the problem, im leaning more towards the belief that the webcam doesnt have a high megapixel count.

 

[Fantus_Longhorn]

It might be worth trying a different colour, it doesn't have to be green; green is used because it's the furthest from skin tones (colour theory). Also, digital cameras use green light to detect luminance so there tends to be double the amount of green detection on the sensor to do this (I'm keeping this real basic :P).

It's not the megapixels that will be the issue, more likely to be an issue with the sensor itself. Also, the white surfaces are likely picking up some reflection from the green sheet, turning them slightly green (even if you can't see it with your own eyes).

So, try a different colour and, if possible, try a different webcam.