[libcamera-devel] [PATCH v2 1/5] ipa: rpi: histogram: Add interBinMean()
Jacopo Mondi
jacopo.mondi at ideasonboard.com
Tue Aug 29 17:18:30 CEST 2023
Hi David
On Wed, Aug 23, 2023 at 01:09:11PM +0100, David Plowman via libcamera-devel wrote:
> 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.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi 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
>
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