[libcamera-devel] [PATCH] ipa: raspberrypi: agc: Fix overflow in Y value calculation

[Naushir Patuck]

Hi David,

Thanks for fixing this.


On Thu, 2 Mar 2023 at 12:57, David Plowman via libcamera-devel <
libcamera-devel at lists.libcamera.org> wrote:

> The maxVal variable in the computeInitialY function needs to be a
> uint64_t, otherwise the subsequent multiplications in the function
> can overflow on relatively high resolution images (when the counts in
> the regions go over 16 bits).
>
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
>

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

PS: patchwork does seem to have correctly recognised Kieran's tag (
https://patchwork.libcamera.org/patch/18330/)


> ---
>  src/ipa/raspberrypi/controller/rpi/agc.cpp | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/ipa/raspberrypi/controller/rpi/agc.cpp
> b/src/ipa/raspberrypi/controller/rpi/agc.cpp
> index ea0c82b5..4ea0dd41 100644
> --- a/src/ipa/raspberrypi/controller/rpi/agc.cpp
> +++ b/src/ipa/raspberrypi/controller/rpi/agc.cpp
> @@ -584,7 +584,7 @@ void Agc::fetchAwbStatus(Metadata *imageMetadata)
>  static double computeInitialY(StatisticsPtr &stats, AwbStatus const &awb,
>                               double weights[], double gain)
>  {
> -       constexpr unsigned int maxVal = 1 <<
> Statistics::NormalisationFactorPow2;
> +       constexpr uint64_t maxVal = 1 <<
> Statistics::NormalisationFactorPow2;
>         /*
>          * Note how the calculation below means that equal weights give you
>          * "average" metering (i.e. all pixels equally important).
> --
> 2.30.2
>
>
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