# What SDR and HDR output transforms does an ALEXA 35 apply in camera under ARRI Color Management, and which LUT files correspond?

- id: art_01M5MSYRE75ANCFM57XDNM2T1R
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T12 · tags: none
- updated: 2026-10-23T16:36:55.279Z
- url: https://veyrul.com/articles/art_01M5MSYRE75ANCFM57XDNM2T1R

ARRI documents four fixed in-camera display render transforms for ALEXA 35/265 under ARRI Color Management: Rec 709 (SDR), Rec 2020 (SDR), Rec 2100 PQ (HDR), Rec 2100 HLG (HDR), each with an equivalent file in the official LogC4 LUT package. A July 2025 naming guideline adds an HLG variant with 203 nit diffuse white (BT.2408) and renames the PQ/HLG colour-space tag from Rec2100 to Rec2020 in file names, while the workflow FAQ still shows the older names. ARRI's pages do not publish tone-map or roll-off parameters for these DRTs.

ARRI documents four fixed in-camera display render transforms for ALEXA 35/265 under ARRI Color Management: Rec 709 (SDR), Rec 2020 (SDR), Rec 2100 PQ (HDR), Rec 2100 HLG (HDR), each with an equivalent file in the official LogC4 LUT package. A July 2025 naming guideline adds an HLG variant with 203 nit diffuse white (BT.2408) and renames the PQ/HLG colour-space tag from Rec2100 to Rec2020 in file names, while the workflow FAQ still shows the older names. ARRI's pages do not publish tone-map or roll-off parameters for these DRTs.

Curator qualifications: Quotes and file names verified. The producer's rights_conflicts entry is a naming discrepancy, not a rights conflict. The 2025-07-10 guideline documents the change itself ('Changed Color Space Tags from Rec2100 to Rec2020'), so the FAQ's Rec2100 names are stale relative to the guideline. This is a supersession relationship, not two contradictory authorities. Reclassify the S9-vs-S12 discrepancy as a documented supersession: the 2025-07-10 LUT naming guideline renamed the PQ/HLG colour-space tags (Rec2100 to Rec2020) and added an HLG DW203 variant. The FAQ (read 2026-10-22) still shows the pre-rename names. It is not a rights conflict; remove it from rights_conflicts_for_curation. Add the HLG DW203 file name (ARRI_LogC4-to-HLG_1K_Rec2020-D65_DW203_v1_65.cube) as the BT.2408 203-nit variant.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://arri.com/en/learn-help/learn-help-camera-system/alexa-35-workflows/alexa-35-workflow-faq",
      "note": "work/arri_a35faq.html (equals producer sha cb0e5357) ALEXA 35 workflow FAQ, DRT table; work/arri_lutnaming.pdf (equals producer sha 722a0974) version history and introduction"
    },
    {
      "url": "https://www.arri.com/resource/blob/294602/99cf69084be7f6638181660483d3e39d/arri-lut-naming-convention-logc4-and-logc3-guideline-en-data.pdf",
      "note": "work/arri_a35faq.html (equals producer sha cb0e5357) ALEXA 35 workflow FAQ, DRT table; work/arri_lutnaming.pdf (equals producer sha 722a0974) version history and introduction"
    },
    {
      "url": "https://www.arri.com/en/learn-help/learn-help-camera-system/image-science/reveal-color-science",
      "note": "work/arri_a35faq.html (equals producer sha cb0e5357) ALEXA 35 workflow FAQ, DRT table; work/arri_lutnaming.pdf (equals producer sha 722a0974) version history and introduction"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] ARRI documents four fixed in-camera display render transforms for ALEXA 35/265 under ARRI Color Management: Rec 709 (SDR), Rec 2020 (SDR), Rec 2100 PQ (HDR), Rec 2100 HLG (HDR), each with an equivalent file in the official LogC4 LUT package. A July 2025 naming guideline adds an HLG variant with 203 nit diffuse white (BT.2408) and renames the PQ/HLG colour-space tag from Rec2100 to Rec2020 in file names, while the workflow FAQ still shows the older names. ARRI's pages do not publish tone-map or roll-off parameters for these DRTs. · locator: work/arri_a35faq.html (equals producer sha cb0e5357) ALEXA 35 workflow FAQ, DRT table; work/arri_lutnaming.pdf (equals producer sha 722a0974) version history and introduction · source: https://arri.com/en/learn-help/learn-help-camera-system/alexa-35-workflows/alexa-35-workflow-faq

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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