[RFC,v3,37/50] ipa: simple: agc: Separate MSV calculation

27586 diff mbox series

Add a separate function that does the MSV calculation.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
---
 src/ipa/simple/algorithms/agc.cpp | 72 ++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 30 deletions(-)

Barnabás Pőcze <barnabas.pocze@ideasonboard.com> writes:

> Add a separate function that does the MSV calculation.
>
> Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>

Reviewed-by: Milan Zamazal <mzamazal@redhat.com>

> ---
>  src/ipa/simple/algorithms/agc.cpp | 72 ++++++++++++++++++-------------
>  1 file changed, 42 insertions(+), 30 deletions(-)
>
> diff --git a/src/ipa/simple/algorithms/agc.cpp b/src/ipa/simple/algorithms/agc.cpp
> index 93505f7665..f959abeba5 100644
> --- a/src/ipa/simple/algorithms/agc.cpp
> +++ b/src/ipa/simple/algorithms/agc.cpp
> @@ -9,6 +9,7 @@
>  
>  #include <algorithm>
>  #include <cmath>
> +#include <optional>
>  #include <stdint.h>
>  
>  #include <libcamera/base/log.h>
> @@ -61,6 +62,44 @@ static constexpr float kExpProportionalGain = 0.04;
>   */
>  static constexpr float kExpMaxStep = 0.15;
>  
> +namespace {
> +
> +std::optional<float> calculateMSV(const SwIspStats::Histogram &histogram, uint8_t blackLevel)
> +{
> +	/*
> +	 * Calculate Mean Sample Value (MSV) according to formula from:
> +	 * https://www.araa.asn.au/acra/acra2007/papers/paper84final.pdf
> +	 */
> +	const unsigned int blackLevelHistIdx =
> +		blackLevel / (256 / SwIspStats::kYHistogramSize);
> +	const unsigned int histogramSize =
> +		SwIspStats::kYHistogramSize - blackLevelHistIdx;
> +	const unsigned int yHistValsPerBin = histogramSize / kExposureBinsCount;
> +	const unsigned int yHistValsPerBinMod =
> +		histogramSize / (histogramSize % kExposureBinsCount + 1);
> +	int exposureBins[kExposureBinsCount] = {};
> +	unsigned int denom = 0;
> +	unsigned int num = 0;
> +
> +	if (yHistValsPerBin == 0)
> +		return {};
> +
> +	for (unsigned int i = 0; i < histogramSize; i++) {
> +		unsigned int idx = (i - (i / yHistValsPerBinMod)) / yHistValsPerBin;
> +		exposureBins[idx] += histogram[blackLevelHistIdx + i];
> +	}
> +
> +	for (unsigned int i = 0; i < kExposureBinsCount; i++) {
> +		LOG(IPASoftExposure, Debug) << i << ": " << exposureBins[i];
> +		denom += exposureBins[i];
> +		num += exposureBins[i] * (i + 1);
> +	}
> +
> +	return (denom == 0 ? 0 : static_cast<float>(num) / denom);
> +}
> +
> +} /* namespace */
> +
>  Agc::Agc()
>  {
>  }
> @@ -158,41 +197,14 @@ void Agc::process(IPAContext &context,
>  		return;
>  	}
>  
> -	/*
> -	 * Calculate Mean Sample Value (MSV) according to formula from:
> -	 * https://www.araa.asn.au/acra/acra2007/papers/paper84final.pdf
> -	 */
> -	const auto &histogram = stats->yHistogram;
> -	const unsigned int blackLevelHistIdx =
> -		context.activeState.blc.level / (256 / SwIspStats::kYHistogramSize);
> -	const unsigned int histogramSize =
> -		SwIspStats::kYHistogramSize - blackLevelHistIdx;
> -	const unsigned int yHistValsPerBin = histogramSize / kExposureBinsCount;
> -	const unsigned int yHistValsPerBinMod =
> -		histogramSize / (histogramSize % kExposureBinsCount + 1);
> -	int exposureBins[kExposureBinsCount] = {};
> -	unsigned int denom = 0;
> -	unsigned int num = 0;
> -
> -	if (yHistValsPerBin == 0) {
> +	auto exposureMSV = calculateMSV(stats->yHistogram, context.activeState.blc.level);
> +	if (!exposureMSV) {
>  		LOG(IPASoftExposure, Debug)
>  			<< "Not adjusting exposure due to insufficient histogram data";
>  		return;
>  	}
>  
> -	for (unsigned int i = 0; i < histogramSize; i++) {
> -		unsigned int idx = (i - (i / yHistValsPerBinMod)) / yHistValsPerBin;
> -		exposureBins[idx] += histogram[blackLevelHistIdx + i];
> -	}
> -
> -	for (unsigned int i = 0; i < kExposureBinsCount; i++) {
> -		LOG(IPASoftExposure, Debug) << i << ": " << exposureBins[i];
> -		denom += exposureBins[i];
> -		num += exposureBins[i] * (i + 1);
> -	}
> -
> -	float exposureMSV = (denom == 0 ? 0 : static_cast<float>(num) / denom);
> -	updateExposure(context, frameContext, exposureMSV);
> +	updateExposure(context, frameContext, *exposureMSV);
>  }
>  
>  REGISTER_IPA_ALGORITHM(Agc, "Agc")