[FFmpeg-devel] Discussion about Color and light correction tools in libavfilter

[Michael Niedermayer]

On Tue, Jul 14, 2009 at 12:19:01AM +0200, Stefano Sabatini wrote:
> On date Monday 2009-07-13 10:53:24 +0200, Jean-Michel Pour? encoded:
> > Hello,
> > 
> > I just discovered libavfilter from Soc2007+soc2009.
> > It seems to be oriented toward running filters, like 'watermark'.
> > 
> > IMHO, the most important needs are in color and light correction.
> > 
> > To understand user needs, it is interesting to study a photography
> > correction tool. Of course Gimp, but it has too many features. 
> > 
> > Showfo, which is part of Digikam for KDE4, is much more interesting,
> > because it shows-up only the required material for color/light
> > correction AND it is linked to libcv a high-quality and fast processing
> > library, useful for video also.
> > 
> > To install showfo, you only need to:
> > apt-get install showfoto in Debian SID.
> > 
> > From the interface, we discover that user needs are:
> > * Display a multichannel color graph
> > 
> > Then from the color menu
> > * Curves adjust
> > * Levels adjust
> > * Channel mixer
> > * Color effects
> > * Auto correction
> > * Brightness, contrast, gamma
> > * Hue, saturation, lightness
> > * Invest, black&white
> > * Color management
> > 
> > And enhance :
> > * sharpen
> > * blur
> > * noise reduction
> > 
> > I consider these tools a priority for any video editor.
> > 
> > Why not fetch Showfoto basic code and adapt it to libavfilter Soc? 
> > 
> > This would avoid a long and tedious work. Showfoto is linked to libcv.
> > This would be the only requirement.
> 
> Usually in FFmpeg there is the tendency to avoid external
> dependancies, also the basic filters in lavfi should not require
> external libraries.
> 
> Also I don't think there are problems into implementing filters which
> uses external libraries, maybe it would be even possible to write a
> filter wrapper around a library (the same way as vf_scale.c is a
> wrapper of libswscale), for example vf_gimp.c or vf_showfo.c.

yes, such filter wrapers are very welcome, porting individual filters
is not as its a maintaince nightmare well maybe thats exagerated but
still its more work ...

Besides this, things like level/curve/gamma/mix are very simple filters
that require only <10 lines of code each, whats complex on these filters
would be the user interface. I mean a user interface that provides
feedback like preview, histogramms, ... but then thats for a picture editor
for a video player feedback/preview is a rather simple thing ...


>  
> Also note that in the medium / long term it would be a good idea to
> implement a plugin system for filters, to make easy extend lavfi
> without patching/recompilation.

doesnt seem particularely high importantance ATM 

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No great genius has ever existed without some touch of madness. -- Aristotle
-------------- 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/ffmpeg-devel/attachments/20090714/605d4969/attachment.pgp>