[libcamera-devel] [PATCH v2 06/10] ipa: ipu3: convert AWB to the new algorithm interface

Laurent Pinchart laurent.pinchart at ideasonboard.com
Mon Aug 16 01:51:37 CEST 2021


Hi Jean-Michel,

Thank you for the patch.

On Fri, Aug 13, 2021 at 10:49:56AM +0100, Kieran Bingham wrote:
> On 12/08/2021 17:52, Jean-Michel Hautbois wrote:
> > When the stats are received, pass it with the context to the existing

s/it/them/

> > AWB algorithm. IPAFrameContext now has a new structure to store the
> > gains calculated byt the AWB algorithm.
> 
> s/byt/by/
> 
> > 
> > When a EventFillParams event is received, call prepare() and set the new
> 
> /When a/When an/
> 
> > gains accordingly in the params structure.
> > There is no more a need for the IPU3Awb::initialise() function, as the
> > params are always set in prepare().
> > 
> > Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
> > ---
> >  src/ipa/ipu3/ipa_context.h |  8 ++++
> >  src/ipa/ipu3/ipu3.cpp      |  5 +--
> >  src/ipa/ipu3/ipu3_awb.cpp  | 76 ++++++++++++++++++++------------------
> >  src/ipa/ipu3/ipu3_awb.h    |  6 +--
> >  4 files changed, 54 insertions(+), 41 deletions(-)
> > 
> > diff --git a/src/ipa/ipu3/ipa_context.h b/src/ipa/ipu3/ipa_context.h
> > index e995c663..7bb4f598 100644
> > --- a/src/ipa/ipu3/ipa_context.h
> > +++ b/src/ipa/ipu3/ipa_context.h
> > @@ -38,6 +38,14 @@ struct IPAFrameContext {
> >  		double gain;
> >  	} agc;
> >  
> > +	struct Awb {
> > +		struct Gains {
> > +			double redGain;
> > +			double greenGain;
> > +			double blueGain;
> 
> They're all in a structure called gains, can they be named simpler as
> just 'red', 'green', 'blue' ?

Agree. Also, we don't necessarily need to name the structures here.

> > +		} gains;
> > +	} awb;
> > +
> >  	struct Contrast {
> >  		uint16_t lut[IPU3_UAPI_GAMMA_CORR_LUT_ENTRIES];
> >  	} contrast;
> > diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
> > index e09adfc3..dba5554d 100644
> > --- a/src/ipa/ipu3/ipu3.cpp
> > +++ b/src/ipa/ipu3/ipu3.cpp
> > @@ -230,7 +230,6 @@ int IPAIPU3::configure(const IPAConfigInfo &configInfo)
> >  	}
> >  
> >  	awbAlgo_ = std::make_unique<IPU3Awb>();
> > -	awbAlgo_->initialise(params_, context_.configuration.grid.bdsOutputSize, context_.configuration.grid.bdsGrid);
> >  
> >  	agcAlgo_ = std::make_unique<IPU3Agc>();
> >  	agcAlgo_->initialise(context_.configuration.grid.bdsGrid, sensorInfo_);
> > @@ -311,7 +310,7 @@ void IPAIPU3::fillParams(unsigned int frame, ipu3_uapi_params *params)
> >  		algo->prepare(context_, params_);
> >  
> >  	if (agcAlgo_->updateControls())
> > -		awbAlgo_->updateWbParameters(params_);
> > +		awbAlgo_->prepare(context_, params_);
> >  
> >  	*params = params_;
> >  
> > @@ -337,7 +336,7 @@ void IPAIPU3::parseStatistics(unsigned int frame,
> >  	gain = context_.frameContext.agc.gain;
> >  	gain_ = camHelper_->gainCode(gain);
> >  
> > -	awbAlgo_->calculateWBGains(stats);
> > +	awbAlgo_->process(context_, stats);
> >  
> >  	if (agcAlgo_->updateControls())
> >  		setControls(frame);
> > diff --git a/src/ipa/ipu3/ipu3_awb.cpp b/src/ipa/ipu3/ipu3_awb.cpp
> > index 0f3bcdc9..b422b095 100644
> > --- a/src/ipa/ipu3/ipu3_awb.cpp
> > +++ b/src/ipa/ipu3/ipu3_awb.cpp
> > @@ -121,42 +121,14 @@ IPU3Awb::IPU3Awb()
> >  	asyncResults_.greenGain = 1.0;
> >  	asyncResults_.redGain = 1.0;
> >  	asyncResults_.temperatureK = 4500;
> > +
> > +	zones_.reserve(kAwbStatsSizeX * kAwbStatsSizeY);
> >  }
> >  
> >  IPU3Awb::~IPU3Awb()
> >  {
> >  }
> >  
> > -void IPU3Awb::initialise(ipu3_uapi_params &params, const Size &bdsOutputSize, struct ipu3_uapi_grid_config &bdsGrid)
> > -{
> > -	params.use.acc_awb = 1;
> > -	params.acc_param.awb.config.rgbs_thr_gr = 8191;
> > -	params.acc_param.awb.config.rgbs_thr_r = 8191;
> > -	params.acc_param.awb.config.rgbs_thr_gb = 8191;
> > -	params.acc_param.awb.config.rgbs_thr_b = 8191 | IPU3_UAPI_AWB_RGBS_THR_B_EN | IPU3_UAPI_AWB_RGBS_THR_B_INCL_SAT;
> > -	awbGrid_ = bdsGrid;
> > -
> > -	params.use.acc_bnr = 1;
> > -	params.acc_param.bnr = imguCssBnrDefaults;
> > -	/**
> > -	 * Optical center is column (respectively row) startminus X (respectively Y) center.
> > -	 * For the moment use BDS as a first approximation, but it should
> > -	 * be calculated based on Shading (SHD) parameters.
> > -	 */
> > -	params.acc_param.bnr.column_size = bdsOutputSize.width;
> > -	params.acc_param.bnr.opt_center.x_reset = awbGrid_.x_start - (bdsOutputSize.width / 2);
> > -	params.acc_param.bnr.opt_center.y_reset = awbGrid_.y_start - (bdsOutputSize.height / 2);
> > -	params.acc_param.bnr.opt_center_sqr.x_sqr_reset = params.acc_param.bnr.opt_center.x_reset
> > -							* params.acc_param.bnr.opt_center.x_reset;
> > -	params.acc_param.bnr.opt_center_sqr.y_sqr_reset = params.acc_param.bnr.opt_center.y_reset
> > -							* params.acc_param.bnr.opt_center.y_reset;
> > -
> > -	params.use.acc_ccm = 1;
> > -	params.acc_param.ccm = imguCssCcmDefault;
> > -
> > -	zones_.reserve(kAwbStatsSizeX * kAwbStatsSizeY);
> > -}
> > -
> >  /**
> >   * The function estimates the correlated color temperature using
> >   * from RGB color space input.
> > @@ -303,17 +275,51 @@ void IPU3Awb::calculateWBGains(const ipu3_uapi_stats_3a *stats)
> >  	}
> >  }
> >  
> > -void IPU3Awb::updateWbParameters(ipu3_uapi_params &params)
> > +void IPU3Awb::process(IPAContext &context, const ipu3_uapi_stats_3a *stats)
> > +{
> > +	calculateWBGains(stats);
> 
> I'd put a new line here.
> 
> Perhaps a comment here saying "
> 
> /*
>  * Gains are only recalculated if enough zones were detected.
>  * The results are cached, so if no results were calculated, we set the
>  * cached values from asyncResults_ here.
>  */
> 
> 
> > +	context.frameContext.awb.gains.blueGain = asyncResults_.blueGain;
> > +	context.frameContext.awb.gains.greenGain = asyncResults_.greenGain;
> > +	context.frameContext.awb.gains.redGain = asyncResults_.redGain;
> > +}
> > +
> > +void IPU3Awb::prepare(IPAContext &context, ipu3_uapi_params &params)
> >  {
> > +	params.use.acc_awb = 1;
> 
> Set enable/use flags last... - or in this instance, after setting the
> awb parameters.

On this topic, btw, I tend to set structure fields in the order in which
they are defined in the structure. I suppose it's a matter of personal
taste.

> > +	params.acc_param.awb.config.rgbs_thr_gr = 8191;
> > +	params.acc_param.awb.config.rgbs_thr_r = 8191;
> > +	params.acc_param.awb.config.rgbs_thr_gb = 8191;
> > +	params.acc_param.awb.config.rgbs_thr_b = 8191 | IPU3_UAPI_AWB_RGBS_THR_B_EN | IPU3_UAPI_AWB_RGBS_THR_B_INCL_SAT;

Line wrap.

> > +	awbGrid_ = context.configuration.grid.bdsGrid;
> > +
> > +	params.use.acc_bnr = 1;
> 
> And this shows that there are modules to further break out of this...

Agreed, I think Bayer noise reduction should be moved to a separate
module, but note that the ImgU groups parameters in a weird way.
params.acc_param.bnr contains much more than noise reduction parameters
(namely at least white balance, lens shading correction and bad pixel
correction). acc_bnr should thus be set if any of those algorithms are
enabled, but we then need to make sure that default values are
programmed for all other algorithms.

> Anything that has it's own 'module' on the IPU3 should have it's own
> corresponding module in the code base I think.

It's a good starting point, but it can sometimes make sense to group or
split modules in different ways, to match how the algorithms are
implemented. I haven't checked, but for instance the AWB and CCM
parameters may make sense to control from a single algorithm.

> > +	params.acc_param.bnr = imguCssBnrDefaults;

Based on the above comment, maybe this should be moved to ipu3.cpp (in a
separate patch though).

> new line?
> 
> > +	/**
> 
> s#/**#/*#
> 
> > +	 * Optical center is column (respectively row) startminus X (respectively Y) center.

I know this is moved from a different location, but I have trouble
understanding the comment. The typo s/startminus/start minus/ could
already be fixed here. Oh, and please reflow the comment to 80 columns.

> > +	 * For the moment use BDS as a first approximation, but it should
> > +	 * be calculated based on Shading (SHD) parameters.
> > +	 */
> > +	Size &bdsOutputSize = context.configuration.grid.bdsOutputSize;
> > +	params.acc_param.bnr.column_size = bdsOutputSize.width;
> > +	params.acc_param.bnr.opt_center.x_reset = awbGrid_.x_start - (bdsOutputSize.width / 2);
> > +	params.acc_param.bnr.opt_center.y_reset = awbGrid_.y_start - (bdsOutputSize.height / 2);
> > +	params.acc_param.bnr.opt_center_sqr.x_sqr_reset = params.acc_param.bnr.opt_center.x_reset
> > +							* params.acc_param.bnr.opt_center.x_reset;
> > +	params.acc_param.bnr.opt_center_sqr.y_sqr_reset = params.acc_param.bnr.opt_center.y_reset
> > +							* params.acc_param.bnr.opt_center.y_reset;
> > +
> > +	params.use.acc_ccm = 1;
> 
> Same, but keep both BNR and CCM here in this patch, and they can move
> out to their own modules separately.
> 
> Fairly trivial comments in this patch.
> 
> With those handled as best as you see fit,
> 
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> > +	params.acc_param.ccm = imguCssCcmDefault;
> > +
> >  	/*
> >  	 * Green gains should not be touched and considered 1.
> >  	 * Default is 16, so do not change it at all.
> >  	 * 4096 is the value for a gain of 1.0
> >  	 */
> > -	params.acc_param.bnr.wb_gains.gr = 16;
> > -	params.acc_param.bnr.wb_gains.r = 4096 * asyncResults_.redGain;
> > -	params.acc_param.bnr.wb_gains.b = 4096 * asyncResults_.blueGain;
> > -	params.acc_param.bnr.wb_gains.gb = 16;
> > +	params.acc_param.bnr.wb_gains.gr = 16 * context.frameContext.awb.gains.greenGain;
> > +	params.acc_param.bnr.wb_gains.r = 4096 * context.frameContext.awb.gains.redGain;
> > +	params.acc_param.bnr.wb_gains.b = 4096 * context.frameContext.awb.gains.blueGain;
> > +	params.acc_param.bnr.wb_gains.gb = 16 * context.frameContext.awb.gains.greenGain;

Does this mean that a gain of 1.0 is encoded as 16 for the green
channels and 4096 for the red and blue channels ?

This also doesn't match the comment in intel-ipu3.h that states

/**
 * struct ipu3_uapi_bnr_static_config_wb_gains_config - White balance gains
 *
 * @gr: white balance gain for Gr channel.
 * @r:  white balance gain for R channel.
 * @b:  white balance gain for B channel.
 * @gb: white balance gain for Gb channel.
 *
 * Precision u3.13, range [0, 8). White balance correction is done by applying
 * a multiplicative gain to each color channels prior to BNR.
 */

This indicates that 1.0 maps to 8192. Do we have evidence that this is
incorrect ?

> >  
> >  	LOG(IPU3Awb, Debug) << "Color temperature estimated: " << asyncResults_.temperatureK;
> >  
> > diff --git a/src/ipa/ipu3/ipu3_awb.h b/src/ipa/ipu3/ipu3_awb.h
> > index eeb2920b..4de3fae2 100644
> > --- a/src/ipa/ipu3/ipu3_awb.h
> > +++ b/src/ipa/ipu3/ipu3_awb.h
> > @@ -29,9 +29,8 @@ public:
> >  	IPU3Awb();
> >  	~IPU3Awb();
> >  
> > -	void initialise(ipu3_uapi_params &params, const Size &bdsOutputSize, struct ipu3_uapi_grid_config &bdsGrid);
> > -	void calculateWBGains(const ipu3_uapi_stats_3a *stats);
> > -	void updateWbParameters(ipu3_uapi_params &params);
> > +	void prepare(IPAContext &context, ipu3_uapi_params &params) override;
> > +	void process(IPAContext &context, const ipu3_uapi_stats_3a *stats) override;
> >  
> >  	struct Ipu3AwbCell {
> >  		unsigned char greenRedAvg;
> > @@ -72,6 +71,7 @@ public:
> >  	};
> >  
> >  private:
> > +	void calculateWBGains(const ipu3_uapi_stats_3a *stats);
> >  	void generateZones(std::vector<RGB> &zones);
> >  	void generateAwbStats(const ipu3_uapi_stats_3a *stats);
> >  	void clearAwbStats();

-- 
Regards,

Laurent Pinchart


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