Ctt fixes #257
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Ctt fixes #257
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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. Signed-off-by: David Plowman <[email protected]>
NaNs can appear if no black dots can be found and analysed in a particular region of the calibration image. There needs to be at least one such dot in every 8x8 cell covering the image. This is now detected, and an error message issued. No CAC tables are generated, so CAC is disabled. Signed-off-by: David Plowman <[email protected]>
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This fixes a couple of calculation issues in the ctt.
The first is a bug in the lens shading calibration measurement, which is now fixed.
The second occurs during CAC calibration, if not enough parts of the image have dots in them. In this case it will print a message and disable CAC.