Concise Radiometric Calibration Using The Power of Ranking

Han Gong, Graham Finlayson, Maryam Mohammadzadeh Darrodi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

18 Downloads (Pure)

Abstract

Compared with raw images, the more common JPEG images are less useful for machine vision algorithms and professional photographers because JPEG-sRGB does not preserve a linear relation between pixel values and the light measured from the scene. A camera is said to be radiometrically calibrated if there is a computational model which can predict how the raw linear sensor image is mapped to the corresponding rendered image (e.g. JPEGs) and vice versa. This paper begins with the observation that the rank order of pixel values are mostly preserved post colour correction. We show that this observation is the key to solving for the whole camera pipeline (colour correction, tone and gamut mapping). Our rank-based calibration method is simpler than the prior art and so is parametrised by fewer variables which, concomitantly, can be solved for using less calibration data. Another advantage is that we can derive the camera pipeline from a single pair of raw-JPEG images. Experiments demonstrate that our method delivers state-of-the-art results (especially for the most interesting case of JPEG to raw).
Original languageEnglish
Title of host publicationBritish Machine Vision Conference (BMVC)
PublisherBMVA Press
DOIs
Publication statusPublished - 4 Sep 2017

Keywords

  • radiometric calibration
  • rank-based

Cite this