[libcamera-devel] [PATCH v3 5/5] ipa: raspberrypi: Normalise region sums to 16-bits
Kieran Bingham
kieran.bingham at ideasonboard.com
Tue Jan 31 14:53:38 CET 2023
Quoting Kieran Bingham (2023-01-31 13:52:40)
> Quoting Naushir Patuck (2023-01-31 12:29:07)
> > Hi Kieran,
> >
> > On Mon, 30 Jan 2023 at 13:31, Kieran Bingham
> > <kieran.bingham at ideasonboard.com> wrote:
> > >
> > > Quoting Naushir Patuck via libcamera-devel (2022-12-13 11:48:36)
> > > > The VC4 ISP uses a pipeline bit-depth of 13-bits. The AGC algorithm needs to
> > > > know this bit-depth when computing the Y value for the image.
> > > >
> > > > Instead of hardcoding the VC4 bit-depth in the AGC source code, normalise all
> > > > region sums to 16-bits when filling the Statistics structure. AWB and ALSC are
> > > > agnostic about pipeline depth, so do not need changing.
> > >
> > > pipeline bit-depth to not confuse pipeline depth with the number of
> > > buffers as this term has been used for previously?
> > >
> > > >
> > > > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> > > > Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
> > > > ---
> > > > src/ipa/raspberrypi/controller/rpi/agc.cpp | 10 ++++------
> > > > src/ipa/raspberrypi/raspberrypi.cpp | 16 ++++++++++------
> > > > 2 files changed, 14 insertions(+), 12 deletions(-)
> > > >
> > > > diff --git a/src/ipa/raspberrypi/controller/rpi/agc.cpp b/src/ipa/raspberrypi/controller/rpi/agc.cpp
> > > > index 868c30f03d66..7ec8292d32ff 100644
> > > > --- a/src/ipa/raspberrypi/controller/rpi/agc.cpp
> > > > +++ b/src/ipa/raspberrypi/controller/rpi/agc.cpp
> > > > @@ -28,8 +28,6 @@ LOG_DEFINE_CATEGORY(RPiAgc)
> > > >
> > > > #define NAME "rpi.agc"
> > > >
> > > > -static constexpr unsigned int PipelineBits = 13; /* seems to be a 13-bit pipeline */
> > > > -
> > > > int AgcMeteringMode::read(const libcamera::YamlObject ¶ms)
> > > > {
> > > > const YamlObject &yamlWeights = params["weights"];
> > > > @@ -593,9 +591,9 @@ static double computeInitialY(StatisticsPtr &stats, AwbStatus const &awb,
> > > > double rSum = 0, gSum = 0, bSum = 0, pixelSum = 0;
> > > > for (unsigned int i = 0; i < stats->agcRegions.numRegions(); i++) {
> > > > auto ®ion = stats->agcRegions.get(i);
> > > > - double rAcc = std::min<double>(region.val.rSum * gain, ((1 << PipelineBits) - 1) * region.counted);
> > > > - double gAcc = std::min<double>(region.val.gSum * gain, ((1 << PipelineBits) - 1) * region.counted);
> > > > - double bAcc = std::min<double>(region.val.bSum * gain, ((1 << PipelineBits) - 1) * region.counted);
> > > > + double rAcc = std::min<double>(region.val.rSum * gain, ((1 << 16) - 1) * region.counted);
> > > > + double gAcc = std::min<double>(region.val.gSum * gain, ((1 << 16) - 1) * region.counted);
> > > > + double bAcc = std::min<double>(region.val.bSum * gain, ((1 << 16) - 1) * region.counted);
> > >
> > > 1 << 16 - 1 now looks a bit 'magic', and it may not be clear to a
> > > reader what it's refering to?
> > >
> > > Before it referenced PipelineBits so it was clearer. I expect this
> > > ((1 << 16) - 1)
> > >
> > > could be a constexpr somewhere at the top of the file, or a helper to
> > > wrap the scaling of region.counted?
> > >
> > >
> > > Hrm ... it 'was' already a constexpr at the top...
> > > Is there a reason you chose to hardcode the value here instead of update
> > > (/and or rename) the existing PipelineBits ?
> >
> > Since the generalised statistics are now normalised to 16-bits,
> > perhaps what is needed is to have a constexpr for (1 << 16) - 1 to be
> > (possibly) defined in the statistics structure to indicate the
> > normalisation used?
>
> Perhaps, but we're in src/ipa/raspberrypi/ so it's all up to your
> preference.
>
> I'll merge this series, and if you think it deserves a cleanup on top,
> that should be easy to treat independently.
>
aha - we crossed paths. I'll make sure your new patch still works, and
use that instead of this one. ;-)
--
Kieran
> --
> Kieran
>
>
> >
> > Naush
> >
> > >
> > > Aside from that:
> > >
> > >
> > > Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > >
> > >
> > > > rSum += rAcc * weights[i];
> > > > gSum += gAcc * weights[i];
> > > > bSum += bAcc * weights[i];
> > > > @@ -608,7 +606,7 @@ static double computeInitialY(StatisticsPtr &stats, AwbStatus const &awb,
> > > > double ySum = rSum * awb.gainR * .299 +
> > > > gSum * awb.gainG * .587 +
> > > > bSum * awb.gainB * .114;
> > > > - return ySum / pixelSum / (1 << PipelineBits);
> > > > + return ySum / pixelSum / (1 << 16);
> > > > }
> > > >
> > > > /*
> > > > diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
> > > > index cff079bbafb3..50fdeb4f0478 100644
> > > > --- a/src/ipa/raspberrypi/raspberrypi.cpp
> > > > +++ b/src/ipa/raspberrypi/raspberrypi.cpp
> > > > @@ -1154,11 +1154,15 @@ RPiController::StatisticsPtr IPARPi::fillStatistics(bcm2835_isp_stats *stats) co
> > > > /* RGB histograms are not used, so do not populate them. */
> > > > statistics->yHist = std::move(RPiController::Histogram(stats->hist[0].g_hist, NUM_HISTOGRAM_BINS));
> > > >
> > > > + /*
> > > > + * All region sums are based on a 13-bit pipeline bit-depth. Normalise
> > > > + * this to 16-bits for the AGC/AWB/ALSC algorithms.
> > > > + */
> > > > statistics->awbRegions.init({ DEFAULT_AWB_REGIONS_X, DEFAULT_AWB_REGIONS_Y });
> > > > for (i = 0; i < statistics->awbRegions.numRegions(); i++)
> > > > - statistics->awbRegions.set(i, { { stats->awb_stats[i].r_sum,
> > > > - stats->awb_stats[i].g_sum,
> > > > - stats->awb_stats[i].b_sum },
> > > > + statistics->awbRegions.set(i, { { stats->awb_stats[i].r_sum << 3,
> > > > + stats->awb_stats[i].g_sum << 3,
> > > > + stats->awb_stats[i].b_sum << 3 },
> > > > stats->awb_stats[i].counted,
> > > > stats->awb_stats[i].notcounted });
> > > >
> > > > @@ -1168,9 +1172,9 @@ RPiController::StatisticsPtr IPARPi::fillStatistics(bcm2835_isp_stats *stats) co
> > > > */
> > > > statistics->agcRegions.init(15);
> > > > for (i = 0; i < statistics->agcRegions.numRegions(); i++)
> > > > - statistics->agcRegions.set(i, { { stats->agc_stats[i].r_sum,
> > > > - stats->agc_stats[i].g_sum,
> > > > - stats->agc_stats[i].b_sum },
> > > > + statistics->agcRegions.set(i, { { stats->agc_stats[i].r_sum << 3,
> > > > + stats->agc_stats[i].g_sum << 3,
> > > > + stats->agc_stats[i].b_sum << 3 },
> > > > stats->agc_stats[i].counted,
> > > > stats->awb_stats[i].notcounted });
> > > >
> > > > --
> > > > 2.25.1
> > > >
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