Research: validate ceptWhitePointLuminanceMbr

[xsscx]

TODO

2026-08-05 13:40:38 UTC

IccEncoding.cpp never checks that the profile's white-point luminance is physically
meaningful, so a negative Lw also flows into m_illuminantXYZ and m_surroundXYZ a few
lines above the CAM setup.

From PR #1966 ceptWhitePointLuminanceMbr fixes for: m_illuminantXYZ , m_surroundXYZ, La & Yb 

Originally posted by @xsscx in #1966 (comment)

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[xsscx]

Spec Citation

ICC.2:2023 §12.2.3.2.6 defines wlum as luminance in cd/m²

• specification supplies no zero-as-valid exception
• conversion requires it as a divisor and physical luminance cannot be non-positive
• align to reject non-finite or non-positive values
  • preserve valid inputs unchanged

CI QA Branch #1980

2026-08-05 13:48:55 UTC

• https://github.com/InternationalColorConsortium/iccDEV/tree/ci-qa-issue-1980
• Job - https://github.com/InternationalColorConsortium/iccDEV/actions/runs/31012199263
  • Note: Network Issues on Docker Fetch

[xsscx]

Net Code Change on CI Branch

+    if (!(std::isfinite((double)Lw) && Lw > 0.0f)) {
+      delete pIcc;
+      return icEncConvertBadParams;
+    }

• Plus CTest

[xsscx]

Developer Handoff

2026-08-05 14:56:24 UTC