[libcamera-devel] [PATCH 1/5] ipa: rpi: histogram: Add interBinMean()

[David Plowman]

Actually also s/quatiles/quantiles/ !!

I can send an update to this one (and add my own reviewed-by seeing as
it's Naush's originally).

David

On Mon, 31 Jul 2023 at 10:59, Kieran Bingham
<kieran.bingham at ideasonboard.com> wrote:
>
> Quoting David Plowman via libcamera-devel (2023-07-31 10:46:37)
> > From: Naushir Patuck <naush at raspberrypi.com>
> >
> > Add a new helper function Histogram::interBinMean() that essentially
> > replaces the existing Histogram::interQuantileMean() logic but working on
> > bins instead.
> >
> > Rework the interQuantileMean() to call into interBinMean() with the
> > appropriate convertion from quatiles to bins.
>
> /convertion/conversion/
>
> >
> > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
>
>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>
> > ---
> >  src/ipa/rpi/controller/histogram.cpp | 22 ++++++++++++++--------
> >  src/ipa/rpi/controller/histogram.h   |  2 ++
> >  2 files changed, 16 insertions(+), 8 deletions(-)
> >
> > diff --git a/src/ipa/rpi/controller/histogram.cpp b/src/ipa/rpi/controller/histogram.cpp
> > index 16a9207f..0a27ba2c 100644
> > --- a/src/ipa/rpi/controller/histogram.cpp
> > +++ b/src/ipa/rpi/controller/histogram.cpp
> > @@ -45,20 +45,26 @@ double Histogram::quantile(double q, int first, int last) const
> >         return first + frac;
> >  }
> >
> > -double Histogram::interQuantileMean(double qLo, double qHi) const
> > +double Histogram::interBinMean(double binLo, double binHi) const
> >  {
> > -       assert(qHi > qLo);
> > -       double pLo = quantile(qLo);
> > -       double pHi = quantile(qHi, (int)pLo);
> > +       assert(binHi > binLo);
> >         double sumBinFreq = 0, cumulFreq = 0;
> > -       for (double pNext = floor(pLo) + 1.0; pNext <= ceil(pHi);
> > -            pLo = pNext, pNext += 1.0) {
> > -               int bin = floor(pLo);
> > +       for (double binNext = floor(binLo) + 1.0; binNext <= ceil(binHi);
> > +            binLo = binNext, binNext += 1.0) {
> > +               int bin = floor(binLo);
> >                 double freq = (cumulative_[bin + 1] - cumulative_[bin]) *
> > -                             (std::min(pNext, pHi) - pLo);
> > +                             (std::min(binNext, binHi) - binLo);
> >                 sumBinFreq += bin * freq;
> >                 cumulFreq += freq;
> >         }
> >         /* add 0.5 to give an average for bin mid-points */
> >         return sumBinFreq / cumulFreq + 0.5;
> >  }
> > +
> > +double Histogram::interQuantileMean(double qLo, double qHi) const
> > +{
> > +       assert(qHi > qLo);
> > +       double pLo = quantile(qLo);
> > +       double pHi = quantile(qHi, (int)pLo);
> > +       return interBinMean(pLo, pHi);
> > +}
> > diff --git a/src/ipa/rpi/controller/histogram.h b/src/ipa/rpi/controller/histogram.h
> > index 6b3e3a9e..e2c5509b 100644
> > --- a/src/ipa/rpi/controller/histogram.h
> > +++ b/src/ipa/rpi/controller/histogram.h
> > @@ -38,6 +38,8 @@ public:
> >         uint64_t total() const { return cumulative_[cumulative_.size() - 1]; }
> >         /* Cumulative frequency up to a (fractional) point in a bin. */
> >         uint64_t cumulativeFreq(double bin) const;
> > +       /* Return the mean value between two (fractional) bins. */
> > +       double interBinMean(double binLo, double binHi) const;
> >         /*
> >          * Return the (fractional) bin of the point q (0 <= q <= 1) through the
> >          * histogram. Optionally provide limits to help.
> > --
> > 2.30.2
> >