open-source cross-platform real-time video effects plugin system

PeteBackDropKey

Freeframe ID: 
BCKD
Number of Inputs: 
1
Platform: 
Windows
Platform: 
Mac
Plugin Type: 
Effect
License: 
Open Source
Freeframe Version: 
FF 1.0x
Developer: 
Pete Warden

This effect stores a frame of video, and uses that to mask areas in the current frame that are different from the original 'backdrop' frame. This only works while the camera is completely still, and it helps if you've got a bright, high-contrast, colourful scene. You get out an image that is marked white where the current image differs from the backdrop, and black elsewhere. It's intended that you use this image as a mask, for example so you can apply an effect only to foreground elements in an image.
Parameters

1. Capture Frame
Turn this on to use the current frame as the backdrop. A good time to do this is when there's nothing in shot but the background, then whenever people move in front of the background, they'll show up on the mask.

2. Difference Threshold
This parameter controls how much different part of the current frame has to be from the original backdrop before it's marked on the mask. The lower this value, the less difference there has to be between the backdrop and current image before it's marked on the mask. Low values mean that you mark fewer actual foreground elements as part of the background, but also get more mistakes from noise in the image. With a higher value, you get less noise, but also miss more actual parts of the foreground in the mask.