Op 15 apr 2009, om 16:52 heeft Stas Oskin het volgende geschreven:
Hi.
20
Are you sure that this isn't the result of the wrong scaling?
interpreting YCbCr with its 16-235 range as if it where YUV 0-255.
It's a common mistake to make, but it can be tricky to track down
where the
wrong interpretation is made.
Can you please explain a bit more of it? You basically mean that I
using
only 16-235, while the original image is 0-255, and this what causes
the
issue?
http://en.wikipedia.org/wiki/YCbCr
it comes down to the fact that at some point, YCbCr (16-235) data is
interpreted as YUV data in the range 0-255.
Because of this, the resulting RGB data is not scaled to the full
0-255 range.
This misinterpretation can have different reasons, the source can
report the wrong colorspace, the reader can misinterpret the reported
value, the data can be identified correctly but handled wrong... etc.
The same applies to the encoding..
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