[mapguide-internals] RFC60 - PNG8 color palette
Jason.Birch at nanaimo.ca
Mon Mar 2 01:07:41 EST 2009
I misunderstood. I thought the precomputed values would be the only ones available in the palette. With this in mind, much of my comments are invalid. Additional thoughts follow.
> So the remaining use case is a server serving many fairly
> simple maps in different image formats....is that a common
> use case?
I can only speak to my own use case, but I'm going to be serving multiple maps with base layers. Actually I'm hoping that Fusion 2 will allow me to create dedicated tile-based map definitions, and then include those within other map groups, but I haven't looked into that yet. Anyway, one of the base layers that I'd want would be orthophotos, which I don't think really lend themselves well to 8bits, so I'd want to have a mix of 24bit and 8bit base layers. Not sure how critical this is though; I will likely end up serving the orthos as a dynamic layer.
> The color palette is only used as a hint, it does not omit
> the color quantization happening in the tile service, it just
> adds the base colors
Colour me epiphanized :)
I'm not convinced that there is value in retaining the current method when creating 8bit tiles; it's flawed in all non-trivial use cases. If the propsed method is effective, I would prefer not to see an additional configuration directive. Rather, I would like to see it used as the default method for rendering 8bit tiles, with the potential (now or in the future) of overriding the runtime-calculated palette with a manually crafted one on a per-scale-range basis.
Does the propsed process include the background colour from the map definition as well as point/line/polygon colours for each individual layer?
Does this process inspect symbology (esp. image-based symbols) and label definitions in determining what colours to add to the palette?
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