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vectorcraft/docs
dotCooCoo fe82f68d6f TIFF: a 16-bit CMYK or gray TIFF with alpha converts at 16 bits
Place, Open and relink read a CMYK or grayscale TIFF with an alpha
channel through extra_samples_tiff_rgba, which cut every 16-bit sample
to its high byte before converting it. A faint ink or a low alpha was
lost: cyan 129 at full alpha showed as white, and an alpha of 129
became fully transparent.

The samples are now normalized at the depth the file stores them, and
only the resulting color and alpha are rounded to 8 bits (a 16-bit
alpha to the nearest 8-bit value). Associated alpha is divided out at
16 bits. A pixel whose associated alpha is zero now has no color,
instead of keeping its stored color. TIFF 6.0's Associated Alpha
Handling section states this arithmetic and the zero-alpha rule for
RGB data; applying them to CMYK and gray samples is VectorCraft's own
rule.
2026-11-14 03:44:41 -08:00
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