How to calculate x and y pixel width for world file?

[Paul Maine(ATS)]

I am using ESRI SOAP webservices to obtain a map for use with Mapserver. I
know that in order to use the map that is formatted as a gif - that I need
to create world file.

Since I know the extent of the map image - do I need to use a world file?

See the following for info on how to create a world file:

http://mapserver.gis.umn.edu/docs/howto/raster_data/#georeference-with-world


How can I obtain the x and y pixel widths from the following information
that is returned from the web service? I am creating the map as an 800 x 800
pixel gif file.

Here is the relevant information that is returned by the webservice:


<n2:MapImageInfo xsi:type='n2:MapImageInfo'>
...
      <mapArea xsi:type='n2:MapArea'>
...
       <extent xsi:type='n3:Envelope'>
...        <projection xsi:type='xsd:string'>4326</projection>
...
        <maxX xsi:type='xsd:double'>-117.10667</maxX>
        <maxY xsi:type='xsd:double'>34.13056</maxY>
        <minX xsi:type='xsd:double'>-117.25667</minX>
        <minY xsi:type='xsd:double'>33.98056</minY>



Thank You