[libcamera-devel] [RFC PATCH 0/1] IPU3 AWB gains correction

[Cao, Bingbu]

JM and Laurent,

I get some pseudo code from Algo which to calculate the gain
settings from awb results, I hope it can help you.

--------------------------------------------------------

inline int Real2fix(unsigned N, double x)
{
      return static_cast<int>(x * (1<<N) +
		(x > 0 ? 0.5 : -0.5));
}

final_b_per_g=awb_results->final_b_per_g;
final_r_per_g=awb_results->final_r_per_g;

float max_ratio = MAX(MAX(final_b_per_g, final_r_per_g), 
			1.0f);

wb_gains->r = static_cast<unsigned short>(
	Clamp<wb_apply_min_, wb_apply_max_>(Real2fix<13>(
	max_ratio / final_r_per_g - 1)));

wb_gains->b = static_cast<unsigned short>(
	Clamp<wb_apply_min_, wb_apply_max_>(Real2fix<13>(
	max_ratio / final_b_per_g - 1)));

wb_gains->gr =  wb_gains->gb =  static_cast<unsigned short>(
	Clamp<wb_apply_min_, wb_apply_max_>(Real2fix<13>(
	max_ratio - 1)));

--------------------------------------------------------
BTW, I checked the 2nd picture, it is better than 3, but it is a
little pinkish.

________________________
BRs,  
Bingbu Cao 

> -----Original Message-----
> From: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
> Sent: Friday, June 17, 2022 10:40 PM
> To: Cao, Bingbu <bingbu.cao at intel.com>; Laurent Pinchart
> <laurent.pinchart at ideasonboard.com>
> Cc: libcamera-devel at lists.libcamera.org; sakari.ailus at linux.intel.com
> Subject: Re: [libcamera-devel] [RFC PATCH 0/1] IPU3 AWB gains correction
> 
> Thank you.
> FYI, I tested the patch I sent with this fixed [1], and I obtain [2]
> while it is [3] on master.
> 
> [1]: https://patchwork.libcamera.org/patch/16256/
> [2]: https://pasteboard.co/sPXz45GjbpAg.png
> [3]: https://pasteboard.co/DLfD69BzsFuu.png
> 
> Waiting for your confirmation ;-).
> JM
> 
> On 17/06/2022 15:30, Cao, Bingbu via libcamera-devel wrote:
> > Laurent and JM,
> >
> > Give me some time, let me confirm with our algo team.
> >
> > ________________________
> > BRs,
> > Bingbu Cao
> >
> >> -----Original Message-----
> >> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> >> Sent: Friday, June 17, 2022 4:08 PM
> >> To: Cao, Bingbu <bingbu.cao at intel.com>
> >> Cc: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>;
> >> libcamera-devel at lists.libcamera.org; sakari.ailus at linux.intel.com
> >> Subject: Re: [libcamera-devel] [RFC PATCH 0/1] IPU3 AWB gains
> >> correction
> >>
> >> Hi Bingbu,
> >>
> >> Thank you very much for your quick reply.
> >>
> >> On Fri, Jun 17, 2022 at 06:58:36AM +0000, Cao, Bingbu via
> >> libcamera-devel
> >> wrote:
> >>> Hi, JM,
> >>>
> >>> For BNR parameters WB gain factor for the three channels [Ggr, Ggb,
> >>> Gb,
> >> Gr].
> >>> Their precision is U3.13 and the range is (0, 8) and the actual gain
> >>> is Gx + 1, it is typically Gx = 1.
> >>>
> >>> Pout = {Pin * (1 + Gx)}.
> >>>
> >>> So that means for wb_gains.Ggr/gb/g/r = 0.5, the actual gain is 1.5.
> >>
> >> Just to make sure my understanding is correct, does this mean the
> >> following ?
> >>
> >> wb_gains.gr = 0    -> actual gain = 1.0
> >> wb_gains.gr = 4096 -> actual gain = 1.5 wb_gains.gr = 8192 -> actual
> >> gain = 2.0
> >>
> >>> It seems not correct to changing ratio from 8192 to 4096 as its
> >>> precision is U3.13.  I am not familiar with ipa implementation in
> >>> libcamera, not sure other details.
> >>>
> >>>> -----Original Message-----
> >>>> From: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
> >>>> Sent: Thursday, June 16, 2022 5:12 PM
> >>>> To: libcamera-devel at lists.libcamera.org
> >>>> Cc: Cao, Bingbu <bingbu.cao at intel.com>;
> >>>> sakari.ailus at linux.intel.com; Jean-Michel Hautbois
> >>>> <jeanmichel.hautbois at ideasonboard.com>
> >>>> Subject: [RFC PATCH 0/1] IPU3 AWB gains correction
> >>>>
> >>>> Hi there,
> >>>>
> >>>> Bingbu, Sakari, I cc'ed you because this patch is not aligned with
> >>>> the current documentation in the intel-ipu3.h file, could you have
> >>>> a look please ?
> >>>>
> >>>> The part which worries me is that the green gains should be 0 for
> >>>> the white balance to be correct which is not stated in the
> >>>> documentation at all.
> >>>>
> >>>> In order to demonstrate it I captured two frames, [1] is the actual
> >>>> SGo2 image quality, and [2] with this patch applied.
> >>>>
> >>>> [1]: https://pasteboard.co/hUcL4U6eyyAH.png
> >>>> [2]: https://pasteboard.co/2XIbkkL8kitl.png
> >>>>
> >>>> There is a very clear benefit, that's why I submit this RFC as I
> >>>> think it needs to be clarified :-).
> >>>>
> >>>> Thanks !
> >>>> JM
> >>>>
> >>>> Jean-Michel Hautbois (1):
> >>>>    ipa: ipu3: awb: Correct the coefficient factor
> >>>>
> >>>>   src/ipa/ipu3/algorithms/awb.cpp | 8 ++++----
> >>>>   1 file changed, 4 insertions(+), 4 deletions(-)
> >>
> >> --
> >> Regards,
> >>
> >> Laurent Pinchart