Forums > MaxMSP

Feasibility of some sort of video echo effect

January 23, 2012 | 3:09 pm

Does anyone know how easy it would be to achieve the trailing effect as seen in this music video? http://www.youtube.com/watch?v=12zJw9varYE

I’m guessing it could be as simple as getting max to only refresh the pixels that change colour. We just need an idea of how possible this would be, given that we’re a group of students with a fairly limited amount of experience with max/jitter.

Cheers for any help


January 23, 2012 | 7:08 pm

The video you are referencing uses the AfterEffects echo effect.

See here:

http://blog.videohive.net/resources/tut-tuesday-ok-go-wtf-video-effect/

Are you looking to create a realtime version of this effect?


January 23, 2012 | 7:19 pm

This is really just standard-issue keying with feedback. You’d need to set up a backdrop that is easy to key against (deep black, blue, green, etc.), and then use something like the following:

– Pasted Max Patch, click to expand. –

January 24, 2012 | 4:02 pm

This patch seems like it will be extremely useful as a starting point, thanks a lot!!


January 24, 2012 | 4:23 pm

Correct me if I’m wrong but this patch appears to be based around the rate that certain colours of pixels fade? We are wondering if there is a way of making it so ALL colour pixels don’t decay.

My primitive logic tells me that the background colour wouldn’t matter – as long as it remains stationary, any movements in front of it would immediatly overwrite the image. So I’m basically after something that can "burn" the frame onto the screen? Sorry for all my terrible language, I’m a musician so I’m not sure what the correct terms are to use when descibing visual effects.


January 24, 2012 | 4:32 pm

And yes, we’re attempting to do the whole thing in real time as part of an installation.


January 24, 2012 | 9:18 pm

For a clean key, like what you see in the video, it’s going to require controlled lighting, turning off auto-exposure on cameras, and a solid-colored backdrop. The easiest thing to key against in a realtime setting is blackout cloth (using jit.lumakey instead of jit.chromakey), but you’ll get spillage with any black in the foreground. The feedback shouldn’t "fade" unless you have set a fade amount. The settings on the keying object will help you to define what color range should be treated as background, and what should be foreground.


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