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Alexander 2018-03-26 17:34:56 +03:00
parent 3a5f0201f5
commit 845f4dbfe1
1 changed files with 10 additions and 7 deletions
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17
src/libImaging/ColorLUT.c
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@ -144,13 +144,16 @@ ImagingColorLUT3D_linear(Imaging imOut, Imaging imIn, int table_channels,
int size1D, int size2D, int size3D,
INT16* table)
{
/* The fractions are a way to avoid overflow.
For every pixel, we interpolate 8 elements from the table:
current and +1 for every dimension and they combinations.
If we hit the upper cells from the table,
+1 cells will be outside of the table.
With this compensation we never hit the upper cells
but this also doesn't introduce any noticable difference. */
/* This float to int conversion doesn't have rounding
error compensation (+ 0.5) for two reasons:
1. As we don't hit the highest value,
we can use one extra bit for precision.
2. For every pixel, we interpolate 8 elements from the table:
current and +1 for every dimension and they combinations.
If we hit the upper cells from the table,
+1 cells will be outside of the table.
With this compensation we never hit the upper cells
but this also doesn't introduce any noticable difference. */
UINT32 scale1D = (size1D - 1) / 255.0 * (1<<SCALE_BITS);
UINT32 scale2D = (size2D - 1) / 255.0 * (1<<SCALE_BITS);
UINT32 scale3D = (size3D - 1) / 255.0 * (1<<SCALE_BITS);