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<div class="moz-cite-prefix">Mark,<br>
<br>
You could try doing a "gdalinfo -stats" to get the min/max pixel
values, then do a "gdal_translate -scale" to stretch the min/max
values to 0 255 (the full range of an 8-bit band).<br>
<br>
You may be able to do the same thing in mapserver by referencing
a GDAL vrt file with a LUT entry to do the exact same thing as the
above gdal_translate command, but it would be [almost] pointless
(and there would be a performance hit).<br>
<br>
<pre class="moz-signature" cols="72">Best Regards,
Brent Fraser</pre>
On 7/11/2013 8:07 AM, Mark Volz wrote:<br>
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Richard,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
partially figured it out, but I still could use some help.
<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
problem that I had was not with the created image itself,
but how ESRI displayed it. By default ArcMap uses no
stretch to display the SID image while it uses a percent
clip stretch for the created tif . After I changed the
stretch from percent clip to none the images appeared almost
the same, but there was still some differences. Next, I
changed the stretch to minimum-maximum on the created tif
image and I could not tell any difference between the sid
file and the tif image.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Questions:<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo1"><!--[if !supportLists]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><span
style="mso-list:Ignore">1)<span style="font:7.0pt
"Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">When
creating a tiff file in gdal_translate, can I adjust
settings so that the new image will appear exactly like the
old image without having to turn stretch to minimum-maximum?<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo1"><!--[if !supportLists]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><span
style="mso-list:Ignore">2)<span style="font:7.0pt
"Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Is
there a way in mapserver to change the stretch from none to
minimum maximum (or other types of stretches if desired) and
if so is there a performance hit?<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo1"><!--[if !supportLists]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><span
style="mso-list:Ignore">3)<span style="font:7.0pt
"Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Is
there a way to modify a tiff file so that any GIS program
including ArcGIS that opens up the file will use the correct
stretch type, or is there a setting within ArcGIS that will
always use a certain type of stretch when it opens up tiff
images?<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Mark
Volz, GISP<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">GIS
Specialist<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in
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1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
Richard Greenwood [<a class="moz-txt-link-freetext" href="mailto:richard.greenwood@gmail.com">mailto:richard.greenwood@gmail.com</a>]
<br>
<b>Sent:</b> Wednesday, July 10, 2013 6:32 PM<br>
<b>To:</b> Mark Volz<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:fwtools@lists.maptools.org">fwtools@lists.maptools.org</a><br>
<b>Subject:</b> Re: [FWTools] gdal translate - air
photo seems washed out after converting image<o:p></o:p></span></p>
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</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<div>
<p class="MsoNormal">On Wed, Jul 10, 2013 at 3:08 PM,
Mark Volz <<a moz-do-not-send="true"
href="mailto:MarkVolz@co.lyon.mn.us" target="_blank">MarkVolz@co.lyon.mn.us</a>>
wrote:<o:p></o:p></p>
<p class="MsoNormal">Hello,<br>
<br>
I converted a mr sid air photo to a tif file. The
colors appear washed out and too bright compared to
the mr sid file.<br>
<br>
<br>
I would like to create an image file that has the
following three characteristics:<br>
<br>
1) Fast for Mapserver to read.<br>
2) Relatively the same size as the MrSID file. - I
would prefer a file size that is no larger than twice
the size of the Mr SID file, even if it means that I
have to take a small hit by using compression<br>
3) retains the same image quality as the original
MrSID file<br>
<br>
The following two commands made the image fast for
mapserver, and relatively small. But the colors were
washed out...<br>
<br>
c:\ms4w\apps\PipestoneMaps\Raster\Picto2013>gdal_translate
-CO TILED=YES -CO PHOTOMETRIC=YCBCR -CO TFW=YES -CO
COMPRESS=JPEG -CO BIGTIFF=YES MNPIPE13-SID-9INCH.sid
New.tif<br>
c:\ms4w\apps\PipestoneMaps\Raster\Picto2013>gdaladdo
-r average --config compress_overview JPEG --config
photometric_overview YCBCR New.tif 2 4 8 16 32 64 128
256<br>
<br>
<br>
What can I do to improve the image quality, while
retaining the speed and a moderate file size?<br>
<br>
Thanks<br>
<br>
Mark Volz, GISP<br>
GIS Specialist<o:p></o:p></p>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt">Mark,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Those are pretty much the
commands that I regularly use to prepare imagery for
mapserver. I have never experienced any noticeable
color distortion. What does it look like with a
straight
<br>
gdal_translate MNPIPE13-SID-9INCH.sid New.tif<o:p></o:p></p>
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<div>
<p class="MsoNormal">obviously that's not what you
want for a final product, but it would be my first
step toward 'debugging' the problem.<br>
<br>
Rich<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><br>
-- <br>
Richard Greenwood<br>
<a moz-do-not-send="true"
href="mailto:richard.greenwood@gmail.com">richard.greenwood@gmail.com</a><br>
<a moz-do-not-send="true"
href="http://www.greenwoodmap.com">www.greenwoodmap.com</a>
<o:p></o:p></p>
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