[mapserver-users] running out of colors in PC256 output

[Richard Greenwood]

Thanks Steve. Yet another beer that I owe you! I've used Photoshop create
palettes for source imagery a long time ago but didn't think of it for the
output.

Hope you're doing well, and as always, I appreciate your help.

Rich


On Sat, Jan 16, 2016 at 8:29 AM, Lime, Steve D (MNIT) <
Steve.Lime at state.mn.us> wrote:

> You can create a predefined palette and use that. Here's an example
> definition:
>
>   OUTPUTFORMAT
>
>     NAME png8
>
>     DRIVER "AGG/PNG"
>
>     MIMETYPE "image/png"
>
>     IMAGEMODE RGB
>
>     EXTENSION "png"
>
>     FORMATOPTION "INTERLACE=OFF"
>
>     FORMATOPTION "PALETTE_FORCE=TRUE"
>
>     FORMATOPTION "PALETTE=/usr/local/mapserver/shared/my.palette" # needs
> to be a full path
>
>   END
>
>
> where the palette file is just a text file with a bunch of RGB triplets:
>
>
>   201,222,252
>
>   40,172,218
>   ...
>
> I've used PhotoShop to take sample MapServer 24-bit output that is
> representative of maps as a whole (shows all feature types and labeling
> scenarios) and create an 8-bit GIF. That software does a nice job of color
> reduction but I'm sure there are other ways. Then you can use gdalinfo to
> extract the palette information. I have a little perl script that parses
> the gdalinfo output if you're interested.
>
> Steve
>
> ------------------------------
> *From:* mapserver-users [mapserver-users-bounces at lists.osgeo.org] on
> behalf of Richard Greenwood [richard.greenwood at gmail.com]
> *Sent:* Friday, January 15, 2016 8:43 PM
> *To:* mapserver
> *Subject:* [mapserver-users] running out of colors in PC256 output
>
> I'm running into more or less the same problem described in this 12 year
> old ticket:
>   https://trac.osgeo.org/mapserver/ticket/397
> In my case black truetype font labels will be rendered in dark green or
> similar when there are a lot of colors in accompanying vector layers with
> anit-aliasing or opacity. I think the 256 color palette gets used up before
> the labels are rendered.
>
> I don't want to go to full RGB output because the image sizes are so much
> larger. If I put a black feature into one of the layers it seems to add it
> to the palette and then the black labels are render correctly in black. But
> that seems pretty kludgy.
>
> Any other suggestions?
>
> Thanks
>
> --
> Richard W. Greenwood, PLS
> www.greenwoodmap.com
>



-- 
Richard W. Greenwood, PLS
www.greenwoodmap.com
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