Advanced

Stray Light Compensation in Optical Systems

Pirinen, Aleksis LU and Toytziaridis, Angelos LU (2015) In Master's Theses in Mathematical Sciences FMA820 20151
Mathematics (Faculty of Engineering)
Abstract
All optical equipment suffers from a phenomenon called stray light, which is defined as unwanted light in an optical system. Images contaminated by stray light tend to have lower contrast and reduced detail, which motivates the need for reducing it in many applications. This master thesis considers computational stray light compensation in digital cameras. In particular, the purpose is to reduce stray light in surveillance cameras developed by Axis Communications. We follow in the spirit of other digital stray light compensation approaches, in which measurements are fit to a parametric shift-variant point spread function (PSF) describing the stray light characteristics of the optical system. The observed contaminated image is modelled as... (More)
All optical equipment suffers from a phenomenon called stray light, which is defined as unwanted light in an optical system. Images contaminated by stray light tend to have lower contrast and reduced detail, which motivates the need for reducing it in many applications. This master thesis considers computational stray light compensation in digital cameras. In particular, the purpose is to reduce stray light in surveillance cameras developed by Axis Communications. We follow in the spirit of other digital stray light compensation approaches, in which measurements are fit to a parametric shift-variant point spread function (PSF) describing the stray light characteristics of the optical system. The observed contaminated image is modelled as an underlying ideal image convolved with the PSF. Once the PSF has been determined, a deconvolution is performed to obtain a restored image. We provide comparisons of a few deconvolution strategies and their performances regarding the restoration of images. Also, we discuss different techniques for decreasing the computational cost of the compensation. An experiment in which the images are compared to a ground-truth is proposed to objectively measure performance. The results indicate that the restored images are closer to the ground-truth compared to the observed image, which implies that the stray light compensation is successful. (Less)
Popular Abstract (Swedish)
se bilaga.
Please use this url to cite or link to this publication:
author
Pirinen, Aleksis LU and Toytziaridis, Angelos LU
supervisor
organization
course
FMA820 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
stray light, point spread function, deconvolution, image processing
publication/series
Master's Theses in Mathematical Sciences
report number
LUTFMA-3279-2015
ISSN
1404-6342
other publication id
2015:E21
language
English
id
5463896
date added to LUP
2015-06-18 12:13:07
date last changed
2015-06-18 12:13:07
@misc{5463896,
  abstract     = {All optical equipment suffers from a phenomenon called stray light, which is defined as unwanted light in an optical system. Images contaminated by stray light tend to have lower contrast and reduced detail, which motivates the need for reducing it in many applications. This master thesis considers computational stray light compensation in digital cameras. In particular, the purpose is to reduce stray light in surveillance cameras developed by Axis Communications. We follow in the spirit of other digital stray light compensation approaches, in which measurements are fit to a parametric shift-variant point spread function (PSF) describing the stray light characteristics of the optical system. The observed contaminated image is modelled as an underlying ideal image convolved with the PSF. Once the PSF has been determined, a deconvolution is performed to obtain a restored image. We provide comparisons of a few deconvolution strategies and their performances regarding the restoration of images. Also, we discuss different techniques for decreasing the computational cost of the compensation. An experiment in which the images are compared to a ground-truth is proposed to objectively measure performance. The results indicate that the restored images are closer to the ground-truth compared to the observed image, which implies that the stray light compensation is successful.},
  author       = {Pirinen, Aleksis and Toytziaridis, Angelos},
  issn         = {1404-6342},
  keyword      = {stray light,point spread function,deconvolution,image processing},
  language     = {eng},
  note         = {Student Paper},
  series       = {Master's Theses in Mathematical Sciences},
  title        = {Stray Light Compensation in Optical Systems},
  year         = {2015},
}