Another example of the pleasantville effect:
http://www.geniusdv.com/weblog/archives/pleasantville_effect_for_final_cut_pro.php
I had not watched Sonnyboo's first video completely at first (the guitar player)...
The guy is painting an alpha channel of what he wants to (de)saturate on the guitarist, I thought at first this kind of
alpha painting was called rotoscoping! But I think rotoscoping is more painting what you see live on the screen, not really alpha masks/selections.
That being said, when you paint masks over time frames, you have to "animate" your selection over time to keep up with the movement (what Sonnyboo said you would spend TONS of time doing), and then you can apply any transformation to your mask, color, opacity... By painting alpha channel I also mean to include drawing polygonal masks in compositing softwares.
But if you plan well your shooting, you key out elements of the image and leave them saturated instead of post-painting colors on moving selections...
In order to achieve the pleasantville effect, everything must be planned before you film I guess. So that the elements that you want to isolate with the software's keyer receive enough light, and the keying will be easy set up. If a pixel is too dark or too bright (black and white selection), you won't be able to select it from a RGB value (chroma selection). So if you want to extract a color from the image, your need enough lighting in your image and also good color contrast between your keyed objects and the rest of the image.
Isn't the pleasantville effect warmer and smoother than selections because the pixel selection over time is based on color (it kind of behave like a wave), instead of angles like painting and masks. Ok ok I need to go to sleep hahaha...
