[theora] Theora Intra (ptalarbvorm) vs. MJPEG

Andrey Filippov theora at elphel.com
Wed May 12 12:27:48 PDT 2010

> I see a lot of sense in these assertions.  However, what pops-up to me
> for a regular user is that it's an additional step they have to take,
> and most tools don't already feature this capability.  It seems that, if
> we incorporate such a codec into the resulting product, then we will
> have to also have software ready for the consumer to use to do the
> post-processing.

Yes, sure it needs software to process. But there are multiple ways how to
make it seamless.

> I'm looking at the page now.  It's very interesting...

That page was designed to be a supplement to the article
but during some site re-design the articles got javascript corrupted

Here is a link to ImageJ plugin for JP46. Additionally it reads Exif
MakerNote field and un-applies gamma and analog gains, so ImageJ gets
floating point pixel data proportional to the number of photons the sensor
actually detected:

> > So far most JP46 images were used for still images (with Elphel model
> > 323 and 353 cameras) but now we at least some solutions for the video
> > and continue to work in this direction. And there could be
> > alternatives to literal JP4 implementation
> I did see some video samples of the JP46 video, but I don't think I saw
> the resulting demosaiced video.

There are several here and there - made by ourselves (i.e.
but you can find much more processed stills made by others.

> It would be great if we had some raw Bayer video footage.  I don't have
> any right now...can anyone point us to some?  It would also be nice if
> JP46 was available as an actual codec to use for "compressing" the raw
> Bayer video as well.  Supposedly my webcam (Logitech Webcam C600) has
> the ability to send raw Bayer pixel data, but I don't know in what
> format that is.

Yes, it could be applicable to other cameras too - JP4 is basically JPEG
with different color components and pixels rearranged for optimal
compression of Bayer data. Funny thing that I am not aware of any software
JP4/JP46 encoder - from the very beginning it ran in the hardware (
http://elphel.cvs.sourceforge.net/viewvc/elphel/elphel353-8.0/fpga/x3x3/) -
modified from the regular color 4:2:0 JPEG I implemented earlier. And there
are multiple software decoders.


PS. We do have cameras available for developers (
http://wiki.elphel.com/index.php?title=Pricing/Discount/Donation_Policy )
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