There is a band_nums parameter (and weights) you can provide to gdal_pansharpen, which led to me thinking about this question in the first place.
band_nums: Optional[Sequence[int]] = None weights: Optional[Sequence[float]] = None So, providing either band_nums=[1,2,3,4] along with weights and extracting bands 1 and 4 after-the-fact, or band_nums=[1,4] and providing the corresponding weights for those bands, in my mind should produce something similar? I haven't tried it just yet. ________________________________ From: Barry DeZonia <bdezo...@gmail.com> Sent: Thursday, January 9, 2025 14:04 To: Even Rouault <even.roua...@spatialys.com> Cc: Joe McGlinchy <j...@aidash.com>; gdal-dev@lists.osgeo.org <gdal-dev@lists.osgeo.org> Subject: Re: [gdal-dev] pansharpen subset of multispectral bands EXTERNAL SENDER. DO NOT click links, or open attachments, if the sender is unknown, or the message seems suspicious in any way. DO NOT provide your user ID or Password. Does that snippet of code need to be that way? It seems it could pretty easily be changed to work a band at a time and a weight of zero would contribute nothing. Now I do not know the domain at all and maybe that violates some assumptions. Curious as to what you think. On Thu, Jan 9, 2025 at 2:36 PM Even Rouault via gdal-dev <gdal-dev@lists.osgeo.org> wrote: > > > Le 09/01/2025 à 20:27, Joe McGlinchy via gdal-dev a écrit : > > Hello, > > I'm wanting to pansharpen only a subset of multispectral bands I have > available. Say for instance I have blue-green-red-nir, and a panchromatic > band, I can calculate the relative weights to specify when using > `gdal_pansharpen` on the full multispectral dataset. If I want to only > pansharpen, for example, the red and NIR bands, is it best to perform the > pansharpening on the full dataset and only retain the bands I need? Or can i > provide only the weights specific to the bands I want to pansharpen? If I can > do the latter (which I can, given the parameter set to `gdal_pansharpen`), do > I need to recalculate those weights, or only provide the subset of weights > for those specific bands? > > Given the formula at > https://gdal.org/en/stable/drivers/raster/vrt.html#gdal-vrttut-pansharpen > > pseudo_panchro[pixel] = sum(weight[i] * spectral[pixel][i] for i=0 to > nb_spectral_bands-1) > ratio = panchro[pixel] / pseudo_panchro[pixel] > for i=0 to nb_spectral_bands-1: > output_value[pixel][i] = input_value[pixel][i] * ratio > > > if you only provide a subset of the input spectral bands, you won't be able > to reconstruct a plausible pseudo_panchro values, hence the scaling ratio > will not be accurate. > > > If your spectral dataset has bands in the R,G,B,NIR order, you can achieve > what you want with: > > > $ gdal_pansharpen panchro.tif rgbnir.tif,band=1 rgbnir.tif,band=2 > rgbnir.tif,band=3 rgbnir.tif,band=4 out.tif -b 1 -b 4 > > Even > > -- > http://www.spatialys.com > My software is free, but my time generally not. > Butcher of all kinds of standards, open or closed formats. At the end, this > is just about bytes. > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/gdal-dev
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