Camera BoF Session Notes
November 17, 2010

Jussi Rautio, Neusoft, convener
Alison Chaiken, Nokia Mobility solutions, note-taker
Michael Yao, Intel UMG
Christian Gaugeraud, Techworks Marine
Antti Klemetti, Nokia MeeGo Imaging
Jing Wang, Intel OTC
Cormac Brick, Movidius
Justin Armstrong, Aspex Semiconductor
Zheng Huan, Intel OTC
Halley Zhao, Intel OTC
Felipe Crochik, CSS LLC
Toni Nikkanen, Teleca Germany
Edward Herve, Collabora Gstreamer maintainer

There are 3 image streams per camera on MeeGo: a video stream, a video
preview stream and a still stream.   Switching between them is slow
because doing so requires a HW resolution reset.   By comparison, the
gstreamer pipeline switch is fast.

The Fcam/Frankencamera project at Stanford garnered a lot of positive
publicity for the N900.  The N900 has more open firmware than other
platforms.  FCam allowed full control of the camera sensor in software
and moved the image processing into software for greater flexibility.
Fcam was Nokia-funded and its future is uncertain.

Fcam most notably allowed acquistion of high-dynamic range images by
acquiring multiple exposures with different shutter opening interval
on one button press.    Acquisition of HDR images is naturally slow
and requires a tripod.     The DCraw and uFRaw plugins of GIMP permit
easy manipulation of HDR images.    

The CheeseCam that's included with PulseAudio is a resource hog.
Going forward, MeeGo will use camerabin for embedded cameras instead.
Rob Clark of TI has already submitted a patch.    libjpeg, libpng and
gstreamer are all part of MeeGo Core.   vlfeat open source libraries
allow more general image processing like Google Goggles although
Google Goggles obviously has a massive backend as well.

libQuill is a Nokia-contributed image post-processing library for
MeeGo.  Each image has an XML-formatted history file that allows easy
reversion.  In the future, an implementation of standard XML to
describe features like horizon position and occurrence of faces would
be useful.  The resulting data could be stored in XMP metadata, which
is extensible, as opposed to EXIF, which is prescribed.

Tile-segmentation of images allows memory consumption to be limited to
the portion which is displayed on-screen.  libQuill has a plugin
architecture will allows easy extension.  QImages have 4 channels, 3
for RGB and one "alpha" that controls transparency.  Use of OpenCV is
under consideration.

A new libQuill mailing list has been started by Jussi.    The face
tracking he has contributed uses a standard algorithm and is a
candidate for inclusion in Qt Mobility.