[OSM-dev] Out of copyright WMS offering - looking for assistance
lists at milliams.com
Mon Oct 19 15:28:23 BST 2009
2009/10/19 Andy Robinson (blackadder-lists) <ajrlists at googlemail.com>:
> Steve Hosgood wrote:
>>Sent: 19 October 2009 9:39 AM
>>To: dev at openstreetmap.org
>>Subject: Re: [OSM-dev] Out of copyright WMS offering - looking for
>>Must they be .jpgs? You'll get a lot of "sharp edge" artefacts using the
>>.jpg format on a map. In theory at least (and in practice whenever I've
>>done it) .png will give better results on material such as that.
> Bear in mind these are printed maps, not rasterised vector maps. We tried
> with png but you can get much lower file size without loosing too much
> definition with the jpg's.
> Now, if someone wants to spend the time proving me wrong they are welcome to
> a an original scan to try it.
I assume you've run something like optipng  over the images. I've
found with complex images you can get quite a size decrease with
'optipng -o7 *.png'. However, if the size of the images at present is
ok, there's no need to change anything. The quality looks fine as it
On another note, in my tests I managed to reduce the size of the
default Mapnik tiles by about 5% but I guess that reduction is small
since they've already been slightly optimised.
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