[mapserver-users] stretching imagery in MapServer

[Andy Colson]

Hi Mark.  Two questions for you:

1) I know it might be a bunch of extra work, but I don't suppose you 
could post some before and after shots (or urls or whatever).  I really 
have no idea what sort of change your talking about.

2) Holy freaking cow you have fast imagery.  I don't suppose you could 
share some processing/hardware/setup secrets?

Thanks

-Andy


On 5/26/2015 2:07 PM, Mark Volz wrote:
> Jukka, (and others)
>
> Thank you for your reply.  I think I figured out how lut works.  If you
> don’t mind please check and make sure I have this correct:
>
> I can use ArcGIS to report the correct input and output values for a
> n=2.5 standard deviation by going to
> layers->symbology->stretch->histograms->Info window.  Once I have those
> values I can modify my map file to include for example:
>
> PROCESSING "LUT_1=73:0,226:255" #changes red band input of 0-73 to 0,
> inputs of 226-255 to 255, inputs between 73-226 linearly interpolated.
>
> PROCESSING "LUT_2=60:0,199:255" #changes green band input of 0-60 to 0,
> inputs of 199-255 to 255, inputs between 60-199 linearly interpolated.
>
> PROCESSING "LUT_3=35:0,155:255" #changes blue band input of 0-35 to 0,
> inputs of 155-255 to 255, inputs between 35-155 linearly interpolated.
>
> P.S.
>
> Before I knew what the heck I was doing with LUT I noticed that I could
> identify wet areas, and tree cover quite easily with the following
> combinations:
>
> PROCESSING "LUT=50:50,60:250,70:250" is a good way to identify tree cover.
>
> PROCESSING "LUT=50:50,60:250,70:70"  is a good way to identify wet areas.
>
> Thank You
>
> Sincerely,
>
> *Mark Volz, GISP*
>
> *From:*Rahkonen Jukka (MML) [mailto:jukka.rahkonen at maanmittauslaitos.fi]
> *Sent:* Monday, May 25, 2015 9:18 AM
> *To:* Mark Volz; mapserver-users at lists.osgeo.org
> *Subject:* Re: stretching imagery in MapServer
>
> Hi,
>
> As far as I know automatic stretch by standard deviation is not supported. You can do automatic min-max stretch with PROCESSING "SCALE=AUTO". If your source data is uniform you may reach a good result with manual scale settings or with PROCESSING “LUT=  “
>
>
>
> -Jukka Rahkonen-
>
> Mark Volz wrote:
>
> Hello,
>
> I added our new Pictometry Air Photos on our mapping site at
> http://geomoose.lyonco.org/geomoose2/geomoose.html.  The air photos seem
> somewhat washed out.  In ArcGIS I was able to get a nicer looking image
> by stretching the air photo using standard deviations. Can we stretch
> imagery in MapServer?  If not please let me know if you have a comment
> regarding how I can improve the image quality.
>
> Thanks
>
> Sincerely,
>
> *Mark Volz, GISP*
>
>
>
> _______________________________________________
> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>