[GRASS-user] unexpected i.pansharpen results
mlennert at club.worldonline.be
Mon Jul 29 01:19:02 PDT 2013
On Mon, July 29, 2013 01:45, Nikos Alexandris wrote:
> Eric Goddard wrote:
>> > I gave up on that pansharpening attempt. I can test some of my imagery
>> > tomorrow and let you know if I still have issues with it.
> Nikos Alexandris wrote:
>> [rest deleted]
>> I can't get any decent looking colors, with any of the methods. I
>> wonder if
>> my images are not properly "aligned" or the like. PCA seems to approach
>> right -- the value ranges seem to fit the reflectance scheme (below 1.0)
>> but the colors are so fancy... ?
>> Will work on it later in the evening.
> To-day/-night I got it to work with 11-bit images! I rescaled them to [0,
> 255] and that seems to work just fine. Even color rebalancing (i.e. of
> Green and Red fusioned with Pan -IKONOS spectral bands) after the
> appears acceptable.
> A bit skeptical though since the rescaling action throws away some of the
> data's details... :-?
> All of my other attempts using out of [0, 255] range values, for example
> Top-of-Atmosphere Reflectances (floating point values < 1.0) or the raw
> IKONOS bands that range between [0, 2047], were not successful.
> So, does i.pansharpen expect only 8-bit images? Can someone confirm or
Looking at the i.pansharpen source code, I see that in all algorithms a
function for histogram matching is called and IIUC, in that function,
values seem to be limited to [0,255].
Maybe you should open a ticket on that.
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