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

[Cao, Bingbu]

Laurent,

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Sent: Monday, June 20, 2022 8:26 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,
> 
> On Mon, Jun 20, 2022 at 12:03:52PM +0000, Cao, Bingbu wrote:
> > 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)
> 
> I suppose this was meant to be
> 
> template<unsigned N>
> inline int Real2fix(double x)
> 
> based on how it's called below.

Yes, you are right, my bad.

> 
> > {
> >       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)));
> 
> Thank you, that clarifies it.

Glad to see it can help you. 😊

> 
> > --------------------------------------------------------
> > BTW, I checked the 2nd picture, it is better than 3, but it is a
> > little pinkish.
> 
> Yes, further improvements are needed. The image is also a bit too dark
> now. Still, it's much better than before :-)
> 
> > > -----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