[mapguide-internals] changing mapguide's image type

[Trevor Wekel]

Hi Walt,

Yes. I agree.  Using a lossy image format for tiles could introduce a
number of undesirable effects.  For tiles of vector-only data, I suspect
JPG will introduce a speckling effect against the hard boudaries of the
various features.

For raster based hybrid tiles, ie. Raster imagery with some overlaid
vector data, a JPG may be appropriate.  The base raster image could
provide enough consistency to reduce edge effects.

Thanks,
Trevor


-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Walt
Welton-Lair
Sent: Tuesday, February 06, 2007 12:08 PM
To: MapGuide Internals Mail List
Subject: RIF: [mapguide-internals] changing mapguide's image type

Think carefully about using any lossy image format for tiles.  To look
correct adjacent tiles need to match at their borders...
 
Walt

	-----Messaggio originale----- 
	Da: mapguide-internals-bounces at lists.osgeo.org per conto di
Trevor Wekel 
	Inviato: lun 2/5/2007 7:21 
	A: MapGuide Internals Mail List 
	Cc: 
	Oggetto: RE: [mapguide-internals] changing mapguide's image type
	
	


	Yes.  I think so.  The tiles and the overlay are two separate
HTTP
	requests.  Tiles could be JPG and overlay could be PNG.  If
you're using
	tiles, then the overlay should be PNG so transparency can be
used to
	show the tiles underneath.
	
	I'm not sure this has been tested though.  It would be
interesting to
	see if the various browsers can deal with overlaying a
transparent PNG
	image over a non-transparent JPG.
	
	And I agree that image type and image size should ideally be set
per
	base layer group.  However, that's a fair bit more work to
implement
	(map definition, Web Studio, Studio, viewers) than adding
configuration
	parameters for default behaviours.
	
	Thanks,
	Trevor
	
	-----Original Message-----
	From: mapguide-internals-bounces at lists.osgeo.org
	[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of
Paul
	Spencer (External)
	Sent: Monday, February 05, 2007 10:57 AM
	To: MapGuide Internals Mail List
	Subject: Re: [mapguide-internals] changing mapguide's image type
	
	Ideally the image type would be set per base layer group.
	
	Paul
	
	On 5-Feb-07, at 12:43 PM, Jason Birch wrote:
	
	>
	> So, if the tiling service image type could be specified, would
that
	> allow Paul to use JPG for the tiles, and the interface would
still use
	
	> PNG for the overlays?
	>
	> Jason
	>
	> -----Original Message-----
	> From: mapguide-internals-bounces at lists.osgeo.org
	> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf
Of
	> Trevor Wekel
	> Sent: Monday, February 05, 2007 09:40
	> To: MapGuide Internals Mail List
	> Subject: RE: [mapguide-internals] changing mapguide's image
type
	>
	>
	> Yes.  Andy is right.  If you're not using tiles then the image
type
	> can be specified.  However, tile generation is currently
hardcoded as
	> PNG.
	>
	> Thanks,
	> Trevor
	> _______________________________________________
	> mapguide-internals mailing list
	> mapguide-internals at lists.osgeo.org
	> http://lists.osgeo.org/mailman/listinfo/mapguide-internals
	
	
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	|Paul Spencer                          pspencer at dmsolutions.ca
|
	
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