Re: [otb-users] How to perform automatic contrast enhancement and color correction ?

[Guillaume Pasero]

Hi Léo, In OTB there is an application to perform basic conversion : otbcli_Convert. This applications allows to convert the dynamic of an image to an output pixels type (linear and log transform supported). It will compute min/max for each band and stretch this dynamic to the output range of your destination pixel type (i.e. 0-255 for uint8). By default, 2% of the histogram are cut on each side (can be tuned). You can also supply a mask to discard pixels during the histogram computation (can be useful for clouds). Regards, Guillaume On 12/12/2016 04:10 AM, Léo HUERTA wrote: Hi everybody, I 'm currently working on Pleiades Datasets, and i would like to perform automatic contrast enhancement and color correction, and i would like to know if anybody know a workflow to do that... I would like to reproduce a thing like "OVR" from Pleiades Data distributed by Airbus Defense & Space. I experimented software like Image magick with this kind of code: convert -monitor -modulate 100,130 -channel R -gamma 1 -channel G -gamma 0.95 -channel B -gamma 0.875 -channel RGB -sigmoidal-contrast 11x40% %OUT%BUNDLE_ORTHO_RGB.TIF -compress lzw %OUT%BUNDLE_ORTHO_RGB_CC.TIF It's not bad but, i spend lot of time trying to find the correct parameters... And i don't know how to calculate them automatically. A good software (but not open source) do a thing like that: Spectral discovery (by Geosage, an Australian company), this software perform L8 pre-processing (for data visualisation only): this soft read metada (MTL files, like DIMAP for pleiades), to estimate parameters for stretching, and scaling to produce a good looking L8 RGB tiff. I think it is possible to do that with the dimap but i don't know how... I have read a good paper about color correction for sat imagery: An Inquiry on Contrast Enhancement Methods for Satellite Images They speak about to very good algo: MSR (Multi Scale Retinex) and LCC (Local Color Correction), but i don't know how to aplly them on my Pleiades dataset. If anyone want to share about contrast enhancement and color correction, i am very happy to share my ressource. Thank you for your time Léo -- -- Check the OTB FAQ at http://www.orfeo-toolbox.org/FAQ.html   You received this message because you are subscribed to the Google Groups "otb-users" group. To post to this group, send email to otb-users@googlegroups.com To unsubscribe from this group, send email to otb-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/otb-users?hl=en --- You received this message because you are subscribed to the Google Groups "otb-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to otb-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout. -- Guillaume PASERO Responsable technique Business Unit ESPACE & GeoInformation - Département Payload Data & Applications CS Systèmes d'Information Parc de la Grande Plaine - 5, Rue Brindejonc des Moulinais - BP 15872 31506 Toulouse Cedex 05 - FRANCE +33 561 17 64 21 - guillaume.pas...@c-s.fr -- -- Check the OTB FAQ at http://www.orfeo-toolbox.org/FAQ.html   You received this message because you are subscribed to the Google Groups "otb-users" group. To post to this group, send email to otb-users@googlegroups.com To unsubscribe from this group, send email to otb-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/otb-users?hl=en --- You received this message because you are subscribed to the Google Groups "otb-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to otb-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.