[mapserver-users] Re: Use of palette file: Problems with changingcolors when tiling

Sat Nov 7 02:48:50 PST 2009

Is this the only way to make it work correctly? It seems a lot easier
to extract all the RGB colors we use from the map file and add that to
the palette file? That is what we have done now, and it will be a lot
more work to actually extract the colors from all the different map
images we then have to create(different colors going from mountain
areas, forest areas down to urban areas).

Espen

2009/11/6 Steve Lime <Steve.Lime at dnr.state.mn.us>:
> Correct. My palette creation process has been to:
>
> 1) create a master image that shows as many possible rendering outputs as possible as a 24-bit PNG.
>
> 2) use a tool to reduce the colors in that image to the desired number and create a 8-bit file. In my case
> I use PhotoShop and produce a gif. Here's a link to the one I used for our rec. compass app but after
> color reduction to 128 colors.
>
>  http://maps.dnr.state.mn.us/compass/remove/compass_color_master.gif
>
> 3) extract a palette from the 8-bit image. I wrote a little perl script that processes gdalinfo output.
>
> 4) my outputformat block is like so:
>
>  OUTPUTFORMAT
>    NAME png
>    DRIVER "AGG/PNG"
>    MIMETYPE "image/png"
>    IMAGEMODE RGB
>    EXTENSION "png"
>    FORMATOPTION "INTERLACE=OFF"
>    FORMATOPTION "PALETTE_FORCE=TRUE"
>    FORMATOPTION "PALETTE=/mapserver/compass/compass.palette"
>  END
>
> I've not had problems with this method...
>
> It's possible there's a bug but it's going to be difficult to fix without a good test case.
>
> Steve
>
>>>> On 11/6/2009 at 9:52 AM, in message
> <a4cd3760911060752i609ad757g9872b8ff5a9b5c27 at mail.gmail.com>, Espen Isaksen
> <espen.isaksen at gmail.com> wrote:
>> Sorry, this still creates trouble. And you have omitted
>>
>> FORMATOPTION   "PALETTE_FORCE=TRUE"
>>
>> on this one. That means it does not use the palette file right?
>>
>> Espen
>>
>>
>> 2009/11/6 Stephen Woodbridge <woodbri at swoodbridge.com>:
>>> Espen,
>>>
>>> Try using this:
>>>
>>>    OUTPUTFORMAT
>>>        NAME agg
>>>        DRIVER "AGG/PNG"
>>>        MIMETYPE "image/png"
>>>        IMAGEMODE RGB
>>>        FORMATOPTION "INTERLACE=false"
>>>        FORMATOPTION "QUANTIZE_FORCE=ON"
>>>        FORMATOPTION "QUANTIZE_DITHER=OFF"
>>>        FORMATOPTION "QUANTIZE_COLORS=256"
>>>        FORMATOPTION "PALETTE=/data/maps/palette.txt"
>>>    END
>>>
>>> And see if it does what you want. Also note that I use "ON" and note "TRUE"
>>> as the value of "QUANTIZE_FORCE", but I'm not sure if the matters or not.
>>>
>>> -Steve
>>>
>>> Espen Isaksen wrote:
>>>>
>>>> Yes, that is what we have been doing all along. I guess I never should
>>>> have mentioned our testing with putting lots of colors in the palette
>>>> file, as it just confuses people :-)
>>>>
>>>> So forget our testing, we have only put the colors we use in the
>>>> mapfile once in the palette file(attached in the first mail), and the
>>>> error in the color is like on the map I attached(first mail).
>>>>
>>>> Espen
>>>>
>>>>
>>>>
>>>> 2009/11/6 Thomas Bonfort <thomas.bonfort at camptocamp.com>:
>>>>>
>>>>> Stephen Woodbridge replied to this thread, and gave the correct usage
>>>>> of the palette file: set the same colors in your palette file as in
>>>>> your mapfile.
>>>>>
>>>>> regards,
>>>>>
>>>>> thomas
>>>>>
>>>>> www.camptocamp.com
>>>>> +33 5 16 57 01 02
>>>>>
>>>>>
>>>>>
>>>>> On Fri, Nov 6, 2009 at 14:24, Espen Isaksen <espen.isaksen at gmail.com>
>>>>> wrote:
>>>>>>
>>>>>> Justed wanted to bring this question into attention again since we did
>>>>>> not get a solution to the problem, and we have not found one either.
>>>>>>
>>>>>> Could this possibly be a bug in Mapserver? Should we report it?
>>>>>>
>>>>>> Espen
>>>>>>
>>>>>>
>>>>>>
>>>>>> 2009/10/28 Espen Isaksen <espen.isaksen at gmail.com>:
>>>>>>>
>>>>>>> Hi!
>>>>>>>
>>>>>>> We are testing out using a palette file in our outputformat to
>>>>>>> decrease file size in the png output. Most of the time this works
>>>>>>> great, but some times when we are tiling the data we get some errors.
>>>>>>> The color seem to shift to a similar color from one tile to another.
>>>>>>>
>>>>>>> We have added the colors we use in the map file in the palette.txt
>>>>>>> file. The documentation says it needs 256 colors in the map file, but
>>>>>>> we do not use that many colors right now. (we tried adding the same
>>>>>>> color more than one time, but that created other problems....)
>>>>>>>
>>>>>>> I have attached a png file showing the problem across a lake. The
>>>>>>> color on the right side is the correct color and the color we have
>>>>>>> added to the palette file. The color on the left side of the lake is
>>>>>>> not something we have set.
>>>>>>>
>>>>>>> I have also added the palette.txt file and the outputformat we use is
>>>>>>> this:
>>>>>>>
>>>>>>>        OUTPUTFORMAT
>>>>>>>                       NAME             "png"
>>>>>>>                       DRIVER           "AGG/PNG"
>>>>>>>                       MIMETYPE         "image/png"
>>>>>>>                       IMAGEMODE        "rgb"
>>>>>>>                       EXTENSION        "png"
>>>>>>>                       FORMATOPTION     "PALETTE_FORCE=TRUE"
>>>>>>>                       FORMATOPTION     "PALETTE=/data/maps/palette.txt"
>>>>>>>                END
>>>>>>>
>>>>>>> Does anybody know why this happens in Mapserver and how to fix it?
>>>>>>>
>>>>>>> Espen
>>>>>>>
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