[GRASS-dev] [GRASS GIS] #2048: i.pansharpen limited to 8-bit imagery

[GRASS GIS]

#2048: i.pansharpen limited to 8-bit imagery
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  Reporter:  Nikos       |      Owner:  grass-dev@…
  Alexandris             |
      Type:  defect      |     Status:  new
  Priority:  normal      |  Milestone:  7.6.1
 Component:  Imagery     |    Version:  svn-trunk
Resolution:              |   Keywords:  i.pansharpen, sharpening, fusion,
                         |  brovey, ihs, pca, 8-bit
       CPU:  All         |   Platform:  Unspecified
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Comment (by Nikos Alexandris):

 Thanks Michael, I've skimmed through.


 1. What justifies the assumption at
 https://trac.osgeo.org/grass/attachment/ticket/2048/i.pansharpen2#L138 and
 L139?

 Instead, what about returning an error, if the input bitness of an image
 is incompatible with what the program can handle, or at least, issue a big
 Warning to the user.


 2. https://trac.osgeo.org/grass/attachment/ticket/2048/i.pansharpen2#L152
 forces 8-bit range.

 Hopefully we can address this too by using something like the modified
 versions of i.rgb.his and i.his.rgb (as demonstrated here
 https://trac.osgeo.org/grass/ticket/774#comment:13). There is no
 mathematical constrain to force an 8-bit range. At least not for IHS and
 PCA. Is there?  Regarding "Brovey", the only assumption I can find by
 quickly searching on the internet, is "It assumes that the spectral range
 spanned by the panchromatic image is the same as that covered by the
 multispectral channels." (source:
 https://desktop.arcgis.com/en/arcmap/10.3/manage-data/raster-and-images
 /fundamentals-of-panchromatic-sharpening.htm).

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2048#comment:33>
GRASS GIS <https://grass.osgeo.org>