[MPlayer-dev-eng] [PATCH] Coring filter

[Guillaume POIRIER]

Hi,

On 6/27/05, Jan Paul Schmidt <jps at fundament.org> wrote:
> 
> Am 27.06.2005 um 01:12 schrieb Rich Felker:
> 
> > On Sun, Jun 26, 2005 at 11:28:12PM +0200, Jan Paul Schmidt wrote:
> >> Hi there,
> >>
> >> this is my type of a coring filter for MPlayer/MEncoder. See
> >> attachments. vf_coring.c is the new filter file and vf_coring.diff the
> >> patches to integrate it into the source tree.
> >>
> >> Coring sets everything below a treshold to black. This coring filter
> >> only uses luminance to make the decision.
> >>
> >> Feedback is really appreciated, as this is my first encounter with the
> >> MPlayer/Mencoder filters.
> >>
> >> jps
> >
> > This filter's not bad as far as I can see, but I question how good the
> > results will be. You'd be better off using eq2 to adjust brightness
> > and contrast so as to clip off the values below a certain level.
> > Otherwise you'll introduce artifacts right at the cutoff threshold,
> > and even if they're not visible on your monitor they'll show up for
> > people with different brightness/gamma settings, especially on lcd
> > panels.
> 
> Well, it is a cheap filter. Coring is always cheap but fast. You may
> get similar result with eq2, but not that easy and fast. To that you
> know for sure everything is zeroed below the treshold, even if you
> might not see it. Coring is for butchering the low levels - no doubt -
> and as always, the quality depends an the user. To reduce artifacts
> there is the black parameter that cores to the treshold instead to
> zero. But this is more like a last resort.
> 
> I guess you are probably questioning the nature of coring :o)

Let me see if I understand correctly what this filter is about:
you give it a threshold, and all areas that are below that threshold
get all painted with the same black.
One benefit I see from this kind of filter is to reduce the amount of
information that a video encoder might have to encode, pretty much
like lumi_mask, but at the filter level...
Am I right about this?

What other practical useful example may you come up with?

Guillaume
-- 
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