[v2,5/6] ipa: simple: blc: Prevent division by zero in BLC
diff mbox series

Message ID 20250911135144.56586-6-mzamazal@redhat.com
State Superseded
Headers show
Series
  • Fix stats related problems in software ISP
Related show

Commit Message

Milan Zamazal Sept. 11, 2025, 1:51 p.m. UTC 
When there are no values in the histogram, BLC simple IPA can crash on
division by zero.  We cannot get anything meaningful in such a case
anyway, let's simply return from `process()' then.

Tested-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
---
 src/ipa/simple/algorithms/blc.cpp | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Maciej S. Szmigiero Sept. 19, 2025, 4:11 a.m. UTC | #1 
On 9/11/25 15:51, Milan Zamazal wrote:
> When there are no values in the histogram, BLC simple IPA can crash on
> division by zero.  We cannot get anything meaningful in such a case
> anyway, let's simply return from `process()' then.
> 
> Tested-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
> Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
> Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
> ---

Reviewed-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>

Thanks,
Maciej

Patch
diff mbox series 

diff --git a/src/ipa/simple/algorithms/blc.cpp b/src/ipa/simple/algorithms/blc.cpp
index 8c1e9ed08..ea5356443 100644
--- a/src/ipa/simple/algorithms/blc.cpp
+++ b/src/ipa/simple/algorithms/blc.cpp
@@ -77,6 +77,11 @@  void BlackLevel::process(IPAContext &context,
 	constexpr float ignoredPercentage = 0.02;
 	const unsigned int total =
 		std::accumulate(begin(histogram), end(histogram), 0);
+	if (total == 0) {
+		LOG(IPASoftBL, Debug) << "Not guessing black level, histogram is empty";
+		return;
+	}
+
 	const unsigned int pixelThreshold = ignoredPercentage * total;
 	const unsigned int histogramRatio = 256 / SwIspStats::kYHistogramSize;
 	const unsigned int currentBlackIdx =