[PATCH 1/5] ipa: libipa: Add black levels to camera sensor helper

[Stefan Klug]

Hi Jacopo,

On Tue, Jul 02, 2024 at 09:53:21AM +0200, Jacopo Mondi wrote:
> Hi Stefan
> 
> On Mon, Jul 01, 2024 at 04:38:24PM GMT, Stefan Klug wrote:
> > For a proper tuning process we need to know the sensor black levels. In
> > most cases these are fixed and not reported by the kernel driver. Store
> > them inside the sensor helpers for later retrieval by the algorithms.
> >
> > Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> > ---
> >  src/ipa/libipa/camera_sensor_helper.cpp | 18 ++++++++++++++++++
> >  src/ipa/libipa/camera_sensor_helper.h   |  6 ++++++
> >  2 files changed, 24 insertions(+)
> >
> > diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp
> > index 782ff9904e81..6d8850eb25a5 100644
> > --- a/src/ipa/libipa/camera_sensor_helper.cpp
> > +++ b/src/ipa/libipa/camera_sensor_helper.cpp
> > @@ -47,6 +47,21 @@ namespace ipa {
> >   * function.
> >   */
> >
> > +/**
> > + * \brief Fetch the black levels of the sensor
> > + *
> > + * This function returns the black levels of the sensor with respect to a 16bit
> > + * pixel width in R, Gr, Gb, B order. If these are unknown an empty optional is
> 
> s/with respect to a 16bit pixel width/expressed as four 16-bits pixel values/

Does that really improve the sentence? Because the values used are
actually 32 bit, to be the same as the metadata type.

> > + * returned.
> > + *
> > + * \return The black levels of the sensor
> , or std::nullopt if not initialized
> 
> > + */
> > +std::optional<CameraSensorHelper::BlackLevels>
> > +CameraSensorHelper::blackLevels() const
> > +{
> > +	return blackLevels_;
> > +}
> > +
> >  /**
> >   * \brief Compute gain code from the analogue gain absolute value
> >   * \param[in] gain The real gain to pass
> > @@ -396,6 +411,7 @@ class CameraSensorHelperImx219 : public CameraSensorHelper
> >  public:
> >  	CameraSensorHelperImx219()
> >  	{
> > +		blackLevels_ = { 4096, 4096, 4096, 4096 };
> >  		gainType_ = AnalogueGainLinear;
> >  		gainConstants_.linear = { 0, 256, -1, 256 };
> >  	}
> > @@ -407,6 +423,7 @@ class CameraSensorHelperImx258 : public CameraSensorHelper
> >  public:
> >  	CameraSensorHelperImx258()
> >  	{
> > +		blackLevels_ = { 4096, 4096, 4096, 4096 };
> >  		gainType_ = AnalogueGainLinear;
> >  		gainConstants_.linear = { 0, 512, -1, 512 };
> >  	}
> > @@ -456,6 +473,7 @@ class CameraSensorHelperImx335 : public CameraSensorHelper
> >  public:
> >  	CameraSensorHelperImx335()
> >  	{
> > +		blackLevels_ = { 3200, 3200, 3200, 3200 };
> 
> I trust you on these values, which I presume come from the sensor's
> datasheets ? If you have measured them instead, I would add them in a
> separate commit with the commit message reporting how these have been
> measured

Yes, these are all from datsheets. I'll add a comment.

All the other commets were already answered by Lauerent and will be
fixed where needed.

Cheers,
Stefan

> 
> >  		gainType_ = AnalogueGainExponential;
> >  		gainConstants_.exp = { 1.0, expGainDb(0.3) };
> >  	}
> > diff --git a/src/ipa/libipa/camera_sensor_helper.h b/src/ipa/libipa/camera_sensor_helper.h
> > index 0d99073bea82..f025727c06ee 100644
> > --- a/src/ipa/libipa/camera_sensor_helper.h
> > +++ b/src/ipa/libipa/camera_sensor_helper.h
> > @@ -9,7 +9,9 @@
> >
> >  #include <stdint.h>
> >
> > +#include <array>
> >  #include <memory>
> > +#include <optional>
> >  #include <string>
> >  #include <vector>
> >
> > @@ -22,9 +24,12 @@ namespace ipa {
> >  class CameraSensorHelper
> >  {
> >  public:
> > +	typedef std::array<int32_t, 4> BlackLevels;
> 
> stupid question: are we sure we will always have 4 values only ? We
> tried not to assume a Bayer pattern in the design of the camera sensor
> helper classes.
> 
> > +
> >  	CameraSensorHelper() = default;
> >  	virtual ~CameraSensorHelper() = default;
> >
> > +	virtual std::optional<BlackLevels> blackLevels() const;
> 
> Should this be virtual ? Is there any case when a derived class will
> have to override this instead of just initializing BlackLevels to the
> desired values ?
> 
> Thanks
>   j
> 
> >  	virtual uint32_t gainCode(double gain) const;
> >  	virtual double gain(uint32_t gainCode) const;
> >
> > @@ -51,6 +56,7 @@ protected:
> >  		AnalogueGainExpConstants exp;
> >  	};
> >
> > +	std::optional<BlackLevels> blackLevels_;
> >  	AnalogueGainType gainType_;
> >  	AnalogueGainConstants gainConstants_;
> >
> > --
> > 2.43.0
> >