From d5db46232e87dd23790c99f8460cb3a920e72668 Mon Sep 17 00:00:00 2001
From: Stefan Klug <stefan.klug@ideasonboard.com>
Date: Wed, 26 Jun 2024 12:33:48 +0200
Subject: libtuning: lsc: Prevent negative values
In cases where the calibration image contains super dark areas, or when
an invalid blacklevel was supplied, the grid might get close to zero or
negative. This would have bad effects on the 1/grid later. So clamp the
values to a small positive number.
Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
---
utils/tuning/libtuning/modules/lsc/lsc.py | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/utils/tuning/libtuning/modules/lsc/lsc.py b/utils/tuning/libtuning/modules/lsc/lsc.py
index 344a07a3..e0ca22eb 100644
--- a/utils/tuning/libtuning/modules/lsc/lsc.py
+++ b/utils/tuning/libtuning/modules/lsc/lsc.py
@@ -59,7 +59,10 @@ class LSC(Module):
def _lsc_single_channel(self, channel: np.array,
image: lt.Image, green_grid: np.array = None):
grid = self._get_grid(channel, image.w, image.h)
- grid -= image.blacklevel_16
+ # Clamp the values to a small positive, so that the following 1/grid
+ # doesn't produce negative results.
+ grid = np.maximum(grid - image.blacklevel_16, 0.1)
+
if green_grid is None:
table = np.reshape(1 / grid, self.sector_shape[::-1])
else:
--
cgit v1.2.1