[gdal-dev] Looking for some gdal-python-math-stuff help: HighLightCompressVisualizer

[Paul Harwood]

Another more common way to address the problem is to perform a log
transform on the image see
https://theailearner.com/2019/01/01/log-transformation/

I am not aware of any ootb log transform libraries. That link above does
show how to do it in OpenCV and numpy. I would probably use Pillow my self
and here is a link talking about how to do that - not my link and I have
never used it so it could be wrong or very slow etc

https://pythontic.com/image-processing/pillow/logarithmic%20transformation

I guess the same thing could be done in GDAL.

On Mon, 10 Oct 2022, 10:40 Stefan Gofferje, <lists at home.gofferje.net> wrote:

> Hi all,
>
> I'm still tinkering on my
> automatic-download-satellite-data-and-create-images-from-my-area scripts
> and I was wondering if anybody could help me out or point me to some math.
>
> I'm currently using percentiles in a little Python script to compress
> the contrast of my images. The result is pretty OK but it breaks if
> large areas of the image are very bright, like clouds or snow.
>
> The Sentinelhub EO Browser offers a function HighlightCompressVisualizer
> (see
>
> https://docs.sentinel-hub.com/api/latest/evalscript/functions/#highlightcompressvisualizer)
>
> which does that "a little" better.
>
> Is there anything comparable in gdal, python or any related library?
> That level of math is a little bit above me. High school was long ago...
>
> T:Stefan
>
> --
>   (o_   Stefan Gofferje            | SCLT, MCP, CCSA
>   //\   Reg'd Linux User #247167   | VCP #2263
>   V_/_  https://www.gofferje.net   | https://www.saakeskus.fi
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/gdal-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20221010/cc322168/attachment.htm>