LYH Studio episode 6 builds every gradient from C=0 M=100 Y=0 K=0 to
C=100 M=0 Y=0 K=0. InDesign blends a gradient's process stops as inks:
halfway is C 50 M 50, a light lilac. DesignCraft converted both ends to
RGB and blended there, so the middle came out a darker violet (117, 88,
189 instead of 135, 119, 181), and every Episode 6 gradient looked
different. A midpoint between CMYK stops also became an RGB colour, so
the PDF shading turned RGB with a conversion warning.
- color: `Color::lerp` blends CMYK with CMYK (or grey), and grey with
grey, in ink space; anything with RGB still blends in RGB.
- `Gradient::display_stops`: the expanded stops plus samples through
each span that isn't RGB at both ends, for renderers that interpolate
in RGB; the screen renderer uses it.
- pdf: a midpoint's expanded stop now keeps the stops' space; the
colour-space test expects no conversion for CMYK or grey midpoints.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
