aiongg 1f0d815477 craft-cms: map device white to device white on every path ...

With a LUT destination, sRGB white came out as 0.3-0.5 % C/M/Y through
Transform::eval and precise float conversions: the legacy Lab encoding
puts L* 100 at 0.996 and a* = 0 at 0.50001, between the BToA grid
nodes, and fix_white only patched the device-link node, so only the
table paths were right.

Transform: for every intent but absolute colorimetric (and proofs
without paper simulation), a pixel equal to the source's device white
gives exactly the destination's device white. fix_white still sets the
device-link node; the paths that do not read that node exactly (the
exact pipeline, float interpolation, and 8-bit lookups when white is no
node) compare each pixel with white once. No other colour changes.
device_white(Lab) had a* = b* = 0.5; Lab white is 128/255 in the v4
encoding, which is no node of the 33-point grid, so Lab sources take
the per-pixel check there too.

Profile: synth::CmykParams::white_on_node maps no ink to exactly
L* 100, a* = b* = 0 in the AToB and gives the BToA tables input curves
that put that white on a node holding no ink. The Coated FOGRA39
profile is regenerated with it and separates PCS white to 2e-5 ink
(was 0.5 %), so the step into white is as smooth as its neighbours.
The default parameters and the Photocraft profile are unchanged; its
white still falls between nodes, so its last grey step into white is
up to about 0.4 % C larger than the one before, as with lcms's
white-node fix, and the test allows that for this profile.

FOGRA39 accuracy against 16a66e1: AToB against the patches unchanged
(mean 0.07, p95 0.18, max 0.53 ΔE00), reference sRGB values unchanged
(max 0.76), Lab -> CMYK -> Lab p95 1.04 -> 1.07, max 2.54 -> 2.55
(mean 0.24).

2026-10-13 01:50:14 +00:00

..

craft-coated-fogra39.icc

craft-cms: map device white to device white on every path

2026-10-13 01:50:14 +00:00

photocraft-coated-cmyk.icc

Add craft-cms: ICC colour management extracted from PhotoCraft

2026-10-13 01:23:45 +00:00