[mapserver-dev] Fwd: Considering a new WMS/WMTS output format: jpeg or png (JPENG for friends)

Even Rouault even.rouault at spatialys.com
Tue Jun 7 10:59:19 PDT 2016

On Tuesday 07 June 2016 14:32:21 Jeff McKenna wrote:
> Forwarding interesting idea on the GeoServer-devel list.  Seems like
> something that would interest MapServer-ers serving through WMS as well.

Sounds like a good idea. WEBP output (available through GDAL if built against 
libwebp) could potentially achieve the same goal (with the bonus of having 
both lossy compression + alpha support), although webp is probably less 
interoperable in browsers, and burn more CPU cycles than JPEG

> -jeff
> -------- Forwarded Message --------
> Subject: 	[Geoserver-devel] Considering a new WMS/WMTS output format:
> jpeg or png (JPENG for friends)
> Date: 	Tue, 7 Jun 2016 18:50:02 +0200
> From: 	Andrea Aime <andrea.aime at geo-solutions.it>
> To: 	Geoserver-devel <geoserver-devel at lists.sourceforge.net>
> Hi all,
> when working with imagery it happens often enough that one wants the
> compression
> factor of a JPEG, but also transparency at the raster data edges.
> Unfortunately one cannot have both... or can she?
> With tiled maps we can introduce a new output format, which I nicknamed
> (JPEg or pNG) that would return the right compression depending on the
> tile content:
> if it's fully opaque, JPEG, if there is any transparency, PNG instead,
> of course setting
> the right return type headers so that the browser can do the right decoding.
> It's simple enough and would save significant bandwidth (and also CPU,
> JPEG is
> faster to compress) for imagery that also needs occasional transparency
> support.
> I'd add this at a WMS output format, and if time allows, WMTS too... but
> no guarantees,
> I have actually no funding backing any of this (I'm doing it for another
> system), but it seems
> quick to implement in GeoServer  too and would be a pity to lose it.
> Objections? Suggestions for a better name (I checked a few other
> variants, but they seem to be
> already in use on the internet with a different meaning)?
> Cheers
> Andrea
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