[MapProxy] Compressing JPEG tiles in YCbCr color space?

[Johannes Kröger (WhereGroup)]

Reconsidering this I think it is just a misunderstanding.

 From what I found, the JPEG tiles generated by MapProxy (via Pillow) DO 
use YCbCr color space and I think this might even be the case for all 
normal JPEG compressed files. I only knew the optimisation in the 
context of GDAL where JPEG is used in GeoTIFF and YCbCr is not the default.

So, it seems like there is no need (or opportunity) to configure 
anything special to get YCbCr JPEG compressed tiles with MapProxy.

Everything about this is kind of hard to really get details on, with 
tools showing different information for the same files. Brrr! :)

Cheers, Hannes

Am 07.06.22 um 12:12 schrieb Johannes Kröger (WhereGroup):
> Hey folk :)
>
> For compressing JPEG imagery it is highly useful to use the YCbCr 
> color space (see e.g. Paul Ramsey's classic 
> https://blog.cleverelephant.ca/2015/02/geotiff-compression-for-dummies.html 
> ). The compression rate is much higher.
>
> Is this possible to setup with MapProxy when using JPEG or GeoTIFF 
> tiles in a cache? I assume it uses RGB by default, at least that's 
> what my googling around PIL/Pillow's default settings got me.
>
> If not, would MapProxy still work as intended and allow a QGIS client 
> to consume its output via WMS/WMTS fine if I was to reencode the tiles 
> in the cache in YCbCr myself?
>
> Cheers, Hannes
>
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-- 
Johannes Kröger / GIS-Entwickler/-Berater

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