Th`ese Marouan BOUALI - Sites personnels de TELECOM ParisTech

12 1. Introduction
A common issue for Earth observing instruments, known as striping effect have persisted
for more then 30 years, i.e, since the launch of Landsat 1. It was since reported on
many imaging spectrometers :
- Landsat Multi Spectral Scanner (MSS) and Thematic Mapper (TM)
- Geostationary Operational Environmental Satellites (GOES)
- Advanced Very High Resolution Radiometer (AVHRR)
- Moderate Resolution Imaging Spectrometer (MODIS)
- Compact High Resolution Imaging Spectrometer (CHRIS)
- HYPERION
- MEdium Resolution Imaging Spectrometer (MERIS)
- Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)
- GLobal Imager (GLI)
- Advanced Land Imager (ALI)
The previous list inludes both whiskbroom and pushbroom sensors which are the two
main techniques used for Earth observation.
Whiskbroom instruments, also known as cross-track scanners acquire a series of lines in
the direction perpendicular to the satellite orbital motion. A scan sweep from one side of
the swath to the other is ensured by a continuously rotating mirror. A limited set of detectors,
sensitive to spectific wavelenghts, then captures the radiation emitted or reflected
by the Earth before its convertion into digital numbers.
Pushbroom sensors (along-track scanners) also exploit the orbital motion of the platform
to generate the second dimension of the acquired signal. They differ from the whiskbroom
design in that the rotating mirror is replaced by a linear array of numerous detectors that
capture simultaneously each pixel of a single scan line.
In both acquisition principles, images are formed by enterlacing or concatanating scan
lines, acquired separately by different detectors. Consequently, the imperfect calibration
of individual detectors induces a sharp pattern across or along the scanning direction that
compromises both visual interpretation and quantitative analysis. More specifically, striping
is disturbingly visible over low-radiance homogeneous regions, which often coincide
with oceanographic areas. In fact, the impact of stripe noise on satellite derived geophysical
variables, including ocean color products, is increasingly attracting the interest of
remote sensing research groups.
Although an extensive litterature has tackled the striping issue, existing techniques are
often not able to satisfie the requirements imposed by several remote sensing applications
namely, complete stripe removal without signal distortion or additional post-processing
artifacts.
The goal of this thesis is to analyse the limitations of standard destriping methods
and to explore the issue of stripe noise removal using variational models. We illustrate the