[COG] Rendering Non-RGB COG's

[Daniel Dufour]

Hi, everyone.  I was wondering if there is a best practice / community
consensus on how to render an arbitrary non-RGB COG?  In other words, how
do we decide what pixel color a raster value corresponds to?  I haven't
kept fully up-to-date on recent developments, so I might totally be missing
something.  As far as I recall, the min and max aren't usually stored in
GeoTIFF metadata.  I came across MinSampleValue[1] and MaxSampleValue[2],
but can't recall seeing them in use before.  Should we be using these tags
to scale a value for rendering?  Or is it more common to compute the
statistics XML or JSON file using GDAL and fetch that?

This question came about as a result of the great work that Michael Hiley
is doing to add COG support to georaster-layer-for-leaflet[3].  You can see
the code here:
https://github.com/GeoTIFF/georaster-layer-for-leaflet/pull/11/files#diff-38ec623c78d873e84e6a002f0cf0f25bR241

Thank you very much for any advice you can provide and have a great weekend!

Sincerely,
Daniel J. Dufour
geotiff.io | geoblaze.io

References
1) https://www.awaresystems.be/imaging/tiff/tifftags/minsamplevalue.html
2) https://www.awaresystems.be/imaging/tiff/tifftags/maxsamplevalue.html
3) https://github.com/GeoTIFF/georaster-layer-for-leaflet
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/cog/attachments/20190118/cbdf71e4/attachment.html>