# What does the DNG 1.7.1.0 specification define for colour matrices, calibration, camera profiles and opcode lists, and what is the exact camera-to-XYZ transform a reader must implement?

- id: art_01M5MR10JJEKV3996BSDTX6T6Q
- 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, T17 · tags: none
- updated: 2026-10-23T16:03:12.075Z
- url: https://veyrul.com/articles/art_01M5MR10JJEKV3996BSDTX6T6Q

DNG 1.7.1.0 (September 2023) requires ColorMatrix1 for every non-monochrome file and gives two routes to camera-to-XYZ (D50): invert the colour matrix (with reduction-matrix or pseudo-inverse variants when there are more than three channels) and then adapt with linear Bradford, or use the ForwardMatrix tags as FM * D * Inverse(AB * CC), which the spec recommends. Camera calibration matrices are applied only when the file's CameraCalibrationSignature exactly matches the profile's ProfileCalibrationSignature. Opcode lists can mark corrections optional, and readers should skip WarpRectilinear/WarpFisheye opcodes that immediately follow an optional WarpRectilinear2, so a conformant reader may legitimately ignore some corrections.

DNG 1.7.1.0 (September 2023) requires ColorMatrix1 for every non-monochrome file and gives two routes to camera-to-XYZ (D50): invert the colour matrix (with reduction-matrix or pseudo-inverse variants when there are more than three channels) and then adapt with linear Bradford, or use the ForwardMatrix tags as FM * D * Inverse(AB * CC), which the spec recommends. Camera calibration matrices are applied only when the file's CameraCalibrationSignature exactly matches the profile's ProfileCalibrationSignature. Opcode lists can mark corrections optional, and readers should skip WarpRectilinear/WarpFisheye opcodes that immediately follow an optional WarpRectilinear2, so a conformant reader may legitimately ignore some corrections.

Curator qualifications: Specification read 2026-10-22; no DNG decoded; arithmetic not executed. Opcode flag-bit details and ProfileEmbedPolicy values (E5-E7) not separately re-read. Adobe hosting blocked curl (403).

Limitations: Specification read 2026-10-22; no DNG decoded; arithmetic not executed.

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

```json
{
  "citations": [
    {
      "url": "https://helpx.adobe.com/content/dam/help/en/photoshop/pdf/DNG_Spec_1_7_1_0.pdf",
      "note": "[producer working copy; not public] sha256 abdecfd8e104e8b8 (equal to pin S47); pdftotext lines 2-3, 1695, 6476-6510; [producer working copy; not public] sha256 abdecfd8e104e8b8 (equal to pin S47); pdftotext lines 2864, 6385, 6586-6596"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] DNG 1.7.1.0 (September 2023) requires ColorMatrix1 for every non-monochrome file and gives two routes to camera-to-XYZ (D50): invert the colour matrix (with reduction-matrix or pseudo-inverse variants when there are more than three channels) and then adapt with linear Bradford, or use the ForwardMatrix tags as FM * D * Inverse(AB * CC), which the spec recommends. Camera calibration matrices are applied only when the file's CameraCalibrationSignature exactly matches the profile's ProfileCalibrationSignature. Opcode lists can mark corrections optional, and readers should skip WarpRectilinear/WarpFisheye opcodes that immediately follow an optional WarpRectilinear2, so a conformant reader may legitimately ignore some corrections. · locator: [producer working copy; not public] sha256 abdecfd8e104e8b8 (equal to pin S47); pdftotext lines 2-3, 1695, 6476-6510; [producer working copy; not public] sha256 abdecfd8e104e8b8 (equal to pin S47); pdftotext lines 2864, 6385, 6586-6596 · source: https://helpx.adobe.com/content/dam/help/en/photoshop/pdf/DNG_Spec_1_7_1_0.pdf

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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