The CHRIS/Proba Toolbox (CHRIS-Box) has been brought into life to support users of data of the CHRIS sensor onboard of the ESA Proba platform. The toolbox has been developed for SNAP and is provided as a plugin. The CHRIS-Box are user tools which ESA/ESRIN is providing free of charge to the Earth Observation Community. Initially the toolbox has been developed for BEAM but has been migrated to SNAP.
The CHRIS-Box software provides extensions for SNAP, which allow accomplishing the following tasks:

  1. Noise reduction: Removes the vertical striping in CHRIS response-corrected images caused by the slit effect and a superposition of high-frequency noise

  2. Cloud screening: Marks cloudy pixels in CHRIS noise-corrected images; the cloud screening algorithm provides cloud probability and abundances for each pixel

  3. Atmospheric correction: Provides a surface reflectance retrieval algorithm. The method applies to noise-corrected radiance images with (or without) a probabilistic cloud mask as generated by the cloud screening algorithm

  4. Geometric correction: Provides a CHRIS/Proba geo-referenced product by using telemetry data and Ground Control Points (GCPs). The resulting product has information on latitude/longitude and viewing geometry for each pixel

  5. TOA reflectance computation: Computes top-of-atmosphere apparent reflectance from the top of atmosphere radiance (radiometrically calibrated data) as provided by the CHRIS noise-corrected images

  6. Feature extraction: Computes certain surface and atmospheric features which are used by the CHRIS-Box cloud screening algorithm; the feature extraction is applicable to TOA reflectance images only

The specific SNAP tools are described on the SNAP Integration page the Algorithm Theoretical Basis Documents are collected on the ATBDs page.


The CHRIS-Box software has been developed by

Both the initial BEAM development and the migration to SNAP took place under ESA/ESRIN contract. Peter Regner (ESRIN) managed the initial development and Espen Volden (ESRIN) managed the migration to SNAP.


The CHRIS-Box can be installed as a toolbox plugin for SNAP.
SNAP can be retrieved from the download page on the STEP website.

The procedure, how a toolbox can be installed, is explained via this guide

Data Source

CHRIS/Proba data can be downloaded from EO Cat.
The data is provided in the SIP format and needs to be manually extracted. When extracting the downloaded
zip file, another zip file appears. This needs to be extracted too. This zip file again contains a zip file.
This one contains the actual CHRIS/Proba data products in the hdf file format.


The CHRIS-Box is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. This program is distributed in the hope it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License v3 for more details.

Source Code

The source code for the CHRIS-Box software is available via the GitHub repository at

Issue Reporting

Issues and feature requests should be reported in the STEP user forum. This is the best way to discuss such reports. The developers will file accepted issues in the in the CHRIS-Box issue tracker.