From 36ba0e5515075f87490048aa1d5f57b6c3864bae Mon Sep 17 00:00:00 2001 From: David Plowman Date: Mon, 28 Apr 2025 11:36:03 +0100 Subject: utils: raspberrypi: ctt: Fix NaNs in lens shading tables The problem occurs when the calculation could lead to a final row (or column) of grid squares with no pixels in them (and hence, NaNs). One specific case is a Pi 5 with an image width (or height) of 1364, so that's 682 Bayer quads. To give 32 grid squares it was calculating 22 quads per cell. However, 31 * 22 = 682 leaving nothing in the final column. The fix is to do a rounding-down division by the number of cells minus one, rather than a rounding-up division by the number of cells. This turns the corner case from one where the final row/column has no pixels to one where we don't quite cover the full image, which is how we have to handle these cases. Bug: https://github.com/raspberrypi/libcamera/issues/254 Signed-off-by: David Plowman Reviewed-by: Naushir Patuck Acked-by: Kieran Bingham Signed-off-by: Kieran Bingham --- utils/raspberrypi/ctt/ctt_alsc.py | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'utils/raspberrypi/ctt/ctt_alsc.py') diff --git a/utils/raspberrypi/ctt/ctt_alsc.py b/utils/raspberrypi/ctt/ctt_alsc.py index 1d94dfa5..f4fd09e3 100644 --- a/utils/raspberrypi/ctt/ctt_alsc.py +++ b/utils/raspberrypi/ctt/ctt_alsc.py @@ -127,11 +127,12 @@ def alsc(Cam, Img, do_alsc_colour, plot=False, grid_size=(16, 12), max_gain=8.0) channels = [Img.channels[i] for i in Img.order] """ calculate size of single rectangle. - -(-(w-1)//32) is a ceiling division. w-1 is to deal robustly with the case - where w is a multiple of 32. + The divisions here must ensure the final row/column of cells has a non-zero number of + pixels. """ w, h = Img.w/2, Img.h/2 - dx, dy = int(-(-(w-1)//grid_w)), int(-(-(h-1)//grid_h)) + dx, dy = (w - 1) // (grid_w - 1), (h - 1) // (grid_h - 1) + """ average the green channels into one """ -- cgit v1.2.1