Flat-field calibration method for hyperspectral frame cameras

Alexander Kokka, Tomi Pulli, Eija Honkavaara, Lauri Markelin, Petri Kärhä, Erkki Ikonen

Research output: Contribution to journalArticleScientificpeer-review

Abstract

This paper presents a method for characterising spatial responsivity of hyperspectral cameras. Knowing the responsivity of the camera as a function of pixel coordinates allows applying a flat-field correction on image data. The method is based on scanning the field of view of the camera with a broadband radiance source, based on an integrating sphere, and combining the captured frames to synthesise a uniform radiance source filling the whole field of view of the camera at the focus distance. The method was compared with a traditional approach where the aperture of an integrating sphere is imaged from a close distance, filling the entire field of view of the camera. The measurement setup was tested with a hyperspectral camera, based on a tunable Fabry-Pérot interferometer. Without the flat-field correction, the average standard deviation of the pixel responsivities across all the spectral channels of the camera was 3.78%. After the correction, the average standard deviation was reduced to 0.40% and 3.25% for the aperture-scanning method and the close-distance method, respectively. The expanded uncertainty (k = 2) for the flat-field correction obtained using the scanning method was 0.68%-0.78%, depending on the spectral channel of the camera.

Original languageEnglish
Article number055001
JournalMetrologia
Volume56
Issue number5
DOIs
Publication statusPublished - 6 Aug 2019
MoE publication typeA1 Journal article-refereed

Fingerprint

Cameras
Calibration
Scanning
Pixels
Interferometers

Keywords

  • calibration
  • camera
  • Fabry-Pérot
  • flat-fielding
  • Hyperspectral
  • measurement uncertainty
  • vignetting

Cite this

Kokka, A., Pulli, T., Honkavaara, E., Markelin, L., Kärhä, P., & Ikonen, E. (2019). Flat-field calibration method for hyperspectral frame cameras. Metrologia, 56(5), [055001]. https://doi.org/10.1088/1681-7575/ab3261
Kokka, Alexander ; Pulli, Tomi ; Honkavaara, Eija ; Markelin, Lauri ; Kärhä, Petri ; Ikonen, Erkki. / Flat-field calibration method for hyperspectral frame cameras. In: Metrologia. 2019 ; Vol. 56, No. 5.
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Kokka, A, Pulli, T, Honkavaara, E, Markelin, L, Kärhä, P & Ikonen, E 2019, 'Flat-field calibration method for hyperspectral frame cameras', Metrologia, vol. 56, no. 5, 055001. https://doi.org/10.1088/1681-7575/ab3261

Flat-field calibration method for hyperspectral frame cameras. / Kokka, Alexander; Pulli, Tomi; Honkavaara, Eija; Markelin, Lauri; Kärhä, Petri; Ikonen, Erkki.

In: Metrologia, Vol. 56, No. 5, 055001, 06.08.2019.

Research output: Contribution to journalArticleScientificpeer-review

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Kokka A, Pulli T, Honkavaara E, Markelin L, Kärhä P, Ikonen E. Flat-field calibration method for hyperspectral frame cameras. Metrologia. 2019 Aug 6;56(5). 055001. https://doi.org/10.1088/1681-7575/ab3261