- a:biLevel (Color > Black and White) was ignored. It is now read, written
and drawn: white where the luminance reaches the threshold, else black
(observed thresholds at 30/50/70% on colour swatches).
- a:alphaInv was ignored; an opaque picture with it is invisible in
PowerPoint. Now read, written and drawn.
- Grayscale, duotone and saturation weighed channels 0.299/0.587/0.114;
PowerPoint's export greys pure red to 54 and green to 182: Rec. 709
weights (0.2126/0.7152/0.0722).
Wild synthetic set: recolour slide 7.60 -> 1.15, picture corrections
13.36 -> 7.36.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
71182b6631