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ipa: rkisp1: awb: Prevent RGB means from being negative

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Due to hardware rounding errors in the YCbCr means, the calculated RGB
means may be negative. This would lead to negative gains, messing up
calculation. Prevent this by clamping the means to positive values.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
This commit is contained in:
Laurent Pinchart
2022-09-04 03:57:08 +03:00
parent 7d0004a410
commit c43c8b1fa0
1 changed files with 10 additions and 0 deletions
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10
src/ipa/rkisp1/algorithms/awb.cpp
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@@ -242,6 +242,16 @@ void Awb::process(IPAContext &context,
redMean = 1.1636 * yMean - 0.0623 * cbMean + 1.6008 * crMean;
greenMean = 1.1636 * yMean - 0.4045 * cbMean - 0.7949 * crMean;
blueMean = 1.1636 * yMean + 1.9912 * cbMean - 0.0250 * crMean;
/*
* Due to hardware rounding errors in the YCbCr means, the
* calculated RGB means may be negative. This would lead to
* negative gains, messing up calculation. Prevent this by
* clamping the means to positive values.
*/
redMean = std::max(redMean, 0.0);
greenMean = std::max(greenMean, 0.0);
blueMean = std::max(blueMean, 0.0);
}
/*