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libtuning: lsc: Prevent negative values

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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>
This commit is contained in:
Stefan Klug 2024-06-26 12:33:48 +02:00
parent e91f6c384f
commit d5db46232e
1 changed files with 4 additions and 1 deletions
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5
utils/tuning/libtuning/modules/lsc/lsc.py
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@ -59,7 +59,10 @@ class LSC(Module):
def _lsc_single_channel(self, channel: np.array, def _lsc_single_channel(self, channel: np.array,
image: lt.Image, green_grid: np.array = None): image: lt.Image, green_grid: np.array = None):
grid = self._get_grid(channel, image.w, image.h) 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: if green_grid is None:
table = np.reshape(1 / grid, self.sector_shape[::-1]) table = np.reshape(1 / grid, self.sector_shape[::-1])
else: else: