[SUGGESTION] ChArUco (and AI ?) camera calibration too

[MarcoRavich]

[Google-DEU]
Hallo, auch wenn LensFun bereits integriert ist, sind natürlich nicht alle Kameras/Objektive verfügbar. Daher wäre es als Ausweichlösung/Alternative sehr hilfreich, einen Assistenten für die Kalibrierungsfunktion „Verzerrungsraster“ bereitzustellen, der auf der Anleitung Matchmove's Distortion Grid - How To basiert.

Ich weiß nicht, ob es technisch umsetzbar ist, aber es wäre interessant, auch ChArUco-basierte Kalibratoren zu nutzen für:

Da FlipsiColor auf KI basiert, schlage ich außerdem vor, auch andere automatisierte Lösungen zu evaluieren/zu integrieren, wie zum Beispiel:

[ENG]
Hi there,
even if LensFun as already integrated not all cameras/lens are of course available in it, so - as a fallback/alternative - it would be very useful to provide a - based on the Matchmove's Distortion Grid - How To - wizard for the "Distortion Grid" calibration feature.

Don't know if it's technically feasible, but it could be interesting to exploit ChArUco-based calibrators too for

Anyway, since FlipsiColor is "AI-based", I also suggest to evaluate/integrate other automatized solutions too such as

Gemeinsame / Common Links

ChArUco

• @Rosatus' Camera Calibration Workbench
• @yumashino's Camera Calibration with ChArUco Board
• @nullboundary's CharucoCalibration;
• @TEXflip's calibration-pattern-generator;

...more at @natowi's CameraCalibTools collection.

KI / AI

• @anthonyreimche's Lens Correction for Safelight;
• @vanyatko126's Automatic Distortion Correction using Optuna;
• @ncquy's Generalized Camera Calibration: Camera Model Selection and Calibration with Effective Image Sampling;
• @AkshatGarg635's AI-Based-DSLR-Camera-Calibration-System.

[TechFlipsi]

Hi Marco,

thanks for the excellent suggestions! I've just implemented ChArUco camera calibration in FlipsiColor.

What's new (commit 87f4ca2):

• New CharucoCalibrator class using OpenCV ArUco marker detection + ChArUco board interpolation
• CalibrateCameraCharuco for sub-pixel-accurate lens distortion correction
• Board generation — you can generate and print a ChArUco board directly from FlipsiColor
• Multi-image calibration (recommended: 5-15 photos from different angles)
• JSON save/load, compatible with the existing DistortionGridCorrector format
• Integrated into the ImagePipeline as an alternative to the chessboard method
• Full path validation and safe JSON deserialization (security hardened)

The ChArUco calibrator works as a fallback for cameras/lenses not in the Lensfun database. It's used automatically when Distortion-Grid is not active but a ChArUco calibration is loaded.

I also looked at the AI-based calibration approaches you linked — those are interesting for a future update. For now, ChArUco covers the most urgent need.

Thanks for the detailed references and links — very helpful!

[TechFlipsi]

Implemented in v0.4.4. ChArUco camera calibration is now available as an alternative to the chessboard Distortion-Grid method. Uses OpenCvSharp4 ArUco API (CharucoBoard, CharucoDetector) with DICT_4X4_50 dictionary.