v.contrast single stream: set the contrast for a stream dual stream: use the brightness of stream 2 to set the contrast for corresponding pixels in stream 1 single stream: set the contrast for a stream dual stream: use the brightness of stream 2 to set the contrast for corresponding pixels in stream 1 In single stream mode, v.contrast adjusts the contrast of each pixel by a value. Streams with int16, int32 and float components are processed in their existing component sizes. For yuv images, you can choose to pass along uv components unchanged. In dual stream mode, v.contrast adjusts the contrast of each pixel in stream 1 by the brightness of the corresponding pixel in stream 2. The streams are both forced to int8 before processing. You can set gain and define how second stream values are interpreted using gain and modulation_center messages.

from the library : softVNS Format : External Environment : jitter / max commercial Max 4.x http://homepage.mac.com/davidrokeby/softVNS.html