Investigate Fuji RAF preview ignoring Kelvin color temperature

[giuseppealbrizio]

Investigate Fuji RAF preview ignoring Kelvin color temperature

Status: Open
Type: Bug / protocol investigation
Created: 2026-05-05

Summary

Fuji camera-backed RAF preview currently appears to ignore Kelvin / Color
Temperature changes in the D185 raw-conversion profile, while WB Shift R/B is
applied correctly.

Evidence

Tested with the RAF workspace diagnostic renders on an X-S20:

• Full recipe 2500K and Full recipe 10000K render visually identical.
• Full recipe WB R+9 B-9 and Full recipe WB R-9 B+9 render with strong,
  expected color shifts.
• The D185 profile payload is 625 bytes and the app patches:
  • WB mode index 12 = 0x8007
  • WB color temp index 15 = requested Kelvin
  • WB shift indices 13/14 = requested R/B shifts

Attempted Fix

Tried temporarily setting live camera props before RAF conversion:

• PTP WhiteBalance 0x5005 = 0x8007
• Fuji ColorTemperature 0xD007 = <Kelvin>

The camera rejected this path with PTP response 0x201c
(InvalidDevicePropValue), so the attempt was rolled back and must not be
treated as a reliable fix.

Current Product Behavior

• Keep Kelvin in recipes and camera preset/write flows.
• In RAF preview, warn that Fuji may keep the RAF file's original color
  temperature.
• Keep WB Shift R/B live in RAF preview because it is verified to work.
• Keep diagnostic variants for Kelvin extremes and WB Shift extremes.

Follow-Up Needed

Capture or otherwise discover the protocol used by FUJIFILM X RAW STUDIO for
Kelvin during RAW conversion. X RAW Studio 1.28.0 on macOS Tahoe 26.4.1 did not
detect the camera even though macOS enumerated it as Fujifilm PTP
(0x04CB:0x02F7), so Wireshark capture was blocked for now.

Acceptance Criteria

• A protocol-level fix makes 2500K vs 10000K visibly different in RAF
  preview without breaking WB Shift.
• If no fix is possible, the limitation is documented and Kelvin remains
  clearly marked as not preview-accurate in the RAF workspace.
• Tests cover any added property/opcode behavior and fallback handling.