[libcamera-devel] [PATCH] ipa: rpi: alsc: Do not allow zero colour ratio statistics

[Naushir Patuck]

Hi David,

Thank you for this fix.

On Wed, 22 Nov 2023 at 09:13, David Plowman via libcamera-devel
<libcamera-devel at lists.libcamera.org> wrote:
>
> The algorithm computes R/G and B/G colour ratio statistics which we
> should not allow to go to zero because there is clearly no gain you
> could apply to R or B to equalise them. Instead flag such regions as
> having "insufficient data" in the normal manner.
>
> Signed-off-by: David Plowman

Missing your email there :)

Reviewed-by: Naushir Patuck <naush at raspberrypi.com>

> ---
>  src/ipa/rpi/controller/rpi/alsc.cpp | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/src/ipa/rpi/controller/rpi/alsc.cpp b/src/ipa/rpi/controller/rpi/alsc.cpp
> index b7413611..8a205c60 100644
> --- a/src/ipa/rpi/controller/rpi/alsc.cpp
> +++ b/src/ipa/rpi/controller/rpi/alsc.cpp
> @@ -548,7 +548,9 @@ static void calculateCrCb(const RgbyRegions &awbRegion, Array2D<double> &cr,
>         for (unsigned int i = 0; i < cr.size(); i++) {
>                 auto s = awbRegion.get(i);
>
> -               if (s.counted <= minCount || s.val.gSum / s.counted <= minG) {
> +               /* Do not return unreliable, or zero, colour ratio statistics. */
> +               if (s.counted <= minCount || s.val.gSum / s.counted <= minG ||
> +                   s.val.rSum / s.counted <= minG || s.val.bSum / s.counted <= minG) {
>                         cr[i] = cb[i] = InsufficientData;
>                         continue;
>                 }
> --
> 2.30.2
>