[Kdenlive-devel] Color spaces and MLT

[Simon Eugster]

Dear friends,

I've just added an RGB parade to kdenlive. While testing I found
something interesting: Although I'm painting on a rect with height 256
(as atm we're dealing with 8 bits per channel only) and scaling the
parade afterwards to the target height, I got kind of scanlines.
Compare these two images:
http://granjow.net/uploads/kdenlive/kdenlive-mlt-rgbparade-noeffect.png
http://granjow.net/uploads/kdenlive/kdenlive-mlt-rgbparade-witheffect.png
With the MLT effect there are scanlines, without it there are none.

This is quite interesting, as this visualizes how color information
gets lost when converting between different color spaces (according to
[1], MLT is using YUV422, the input image is RGB).

Basically I just wanted to show you this because it is interesting.
But in the long term one of our goals should also be to avoid either
conversion to other color spaces or the loss of information caused by
the conversion.

Simon

[1] http://www.mltframework.org/twiki/bin/view/MLT/Framework