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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>We are trying to convert a 16-bit img into an 8-bit tif. Unfortunately,
the colors appear VERY dark (not downconverted, but just plain dark). I
suspect that this has something to do with the histogram. The gdalinfo of
the original image can be found <a href="http://pastebin.com/cmVxRJyE">here</a>.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>When I tell GDAL to convert straight from 16-bit to 8-bit
with:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>gdal_translate -ot Byte -of GTiff 28jan09_worldview_tucumcari_nm.img
output.tif<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I get what looks like the original image with clouds
covering it… almost solid white. (See the gdalinfo <a
href="http://pastebin.com/ike52mMp">here</a>)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>When I scale around 16-bits:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>gdal_translate -ot Byte -of GTiff <b><span style='font-weight:
bold'>-scale 0 65535 0 255</span></b> 28jan09_worldview_tucumcari_nm.img
output.tif<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I get a solid black image. (See the gdalinfo <a
href="http://pastebin.com/XpJL6AQY">here</a>)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>When I scale around the extents specified by the histogram:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>gdal_translate -ot Byte -of GTiff <b><span style='font-weight:
bold'>-scale 117 2047</span></b> 0 255 28jan09_worldview_tucumcari_nm.img
output.tif<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I get the dark image described above. (See the gdalinfo <a
href="http://pastebin.com/Ju4azd47">here</a>)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I suspect if we can get GDAL to process and remove the
histogram, we will not have these issues. Any help in doing this or
further diagnosing the issue would be greatly appreciated.<o:p></o:p></span></font></p>
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