[MPlayer-dev-eng] [PATCH] add 8 bit Bayer format and filter

[Michael Niedermayer]

On Fri, Mar 07, 2008 at 05:42:43AM +0100, Michael Niedermayer wrote:
> On Wed, Mar 05, 2008 at 11:09:48PM -0500, Rich Felker wrote:
> > On Wed, Mar 05, 2008 at 10:17:28PM -0500, Calvin Walton wrote:
> > > On Thu, 2008-03-06 at 00:47 +0100, Michael Niedermayer wrote:
> > > > On Mon, Mar 03, 2008 at 01:40:40PM +0100, Reimar Döffinger wrote:
> > > > > On Mon, Mar 03, 2008 at 01:10:20PM +0100, Nico Sabbi wrote:
> > > > > > new decoders belong to libavcodec
> > > > > 
> > > > > If it was a decoder, though it is more a colourspace converter and as
> > > > > such would be more suitable in libswscale. Either way a filter is the
> > > > > worst solution possible, and both of the better solutions should be
> > > > > submitted to FFmpeg...
> > > > 
> > > > Yes, also iam not completely sure if it fits better into pixelformat or
> > > > compressed stream.
> > > > What it technically is, is the raw data from a color CCD. It is in that
> > > > form only useable with a crop filter. Not even contrast or saturation
> > > > correction could be applied to it without converting it to a normal
> > > > pixel format.
> > > > Also the convertion to a normal pixel format is non trivial and non
> > > > linear and as such an implementation in swscale would be quite seperate from
> > > > everything else.
> > > > There are also dozens of different algorithms to do this convertion and
> > > > they result in very different output.
> > > > Converting it is pretty much identical to guessing missing samples.
> > > 
> > > Guessing missing samples has to be done in lots of cases in swscale,
> > > take a look at a common case like I420 => RGB32: not only do the colour
> > > values need to be converted, but the U and V planes have to be
> > > interpolated up to full picture size first.
> > > 
> > > Swscale is (at least in part) a scaler, and scaling implies
> > > interpolating missing information :)
> 
> I420/YV12/YUY2/... contains chroma planes which have been low pass filtered
> and then some of the samples removed. One can thanks to sampling theory
> recover the missing samples as the sampling rate is above the nyquist
> frequncy. This is of course not absolutely true in practice as images are
> not bandlimited but its true enough to work reasonably well. Also chroma
> is quite unsensitive to resolution loss, images still look nearly the
> same if one throws 3/4 of the chroma samples away.
> 
> What this thread is about is entirely different, there is no lowpass
> filter at all. 
> 
> 
> > 
> > I agree. There's nothing nonlinear about this interpolation. All it
> > requires is the right filter coefficients.
> 
> This reminds me of something mans said about you being an expert in
> everything you never heard of before.
> Anyway ill leave this to you to deal with, i dont have the energy for this
> fight, write some linear interpolation and let the world have some
> entertainment with the resulting images.
> Ive seen the difference, ill post a link to some of the papers if i find
> them again.

http://www.ece.gatech.edu/research/labs/MCCL/pubs/dwnlds/p5.pdf page 17
http://citeseer.ist.psu.edu/723902.html
http://www.ee.technion.ac.il/Sites/People/YoninaEldar/Download/GY2004.pdf

above are just a few random ones, ive a bunch more on my HD but google doesnt
provide any free links to them and its alraedy 6:30 here ...

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

There will always be a question for which you do not know the correct awnser.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/mplayer-dev-eng/attachments/20080307/4054d4ca/attachment.pgp>