Thank you, Even! In the event that we are provided only 4 bands, but from an 8-band system, will this still hold? It is what we have to work with, unfortunately or not.
-Joe ________________________________ From: Even Rouault <even.roua...@spatialys.com> Sent: Thursday, January 9, 2025 13:24 To: 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. 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.
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