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<p class="MsoNormal">Hi everyone,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have multiple Landsat 8 scenes taken on the same day/same path, but they vary in brightness. I believe this to be caused by the time of day that the image was taken as the northern image is brighter (taken earlier in the day) and the
southern image is darker (taken later in the day). This has occurred for multiple images. Is there a way to make the colors match between tiles?
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve attempted to use i.histo.match on my composite rgb images which resulted in distorted colors. Should this tool only be used on grayscale images? Are there other GRASS tools I am not aware of that I should be using? Is the color distortion
caused by any of the other tools that I am using?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Below are the steps that I’ve taken to process my images:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Import all Landsat 8 bands to GRASS 7.0.4<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Convert DN to reflectance<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>i.landsat.toar input=LC81100362016082LGN00_B output=LC81100362016082LGN00_refl metfile=LC81100362016082LGN00_MTL.txt<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Pansharpen using i.fusion.hpf<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>i.fusion.hpf pan=LC81100362016082LGN00_relf8 msx=LC81100362016082LGN00_refl4, LC81100362016082LGN00_relf3, LC81100362016082LGN00_refl2 suffix=hpf<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">4.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Histogram equalization<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>r.colors –e map=LC81100362016082LGN00_refl4.hpf color=grey<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">5.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Color balance using i.colors.enhance<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>i.colors.enhance red=LC81100362016082LGN00_refl4.hpf green=LC81100362016082LGN00_refl3.hpf blue=LC81100362016082LGN00_refl2.hpf<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">6.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Set region<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>g.region raster=LC81100362016082LGN00_refl2.hpf<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">7.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Create RGB composite<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>r.composite red=LC81100362016082LGN00_refl4.hpf green=LC81100362016082LGN00_refl3.hpf blue=LC81100362016082LGN00_refl2.hpf output=LC81100362016082LGN00_refl_rgb<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">8.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>Export image<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>r.out.gdal input= LC81100362016082LGN00_refl_rgb output= LC81100362016082LGN00.tif format=’GTiff’<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Michele Toma<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"><a href="mailto:michele.toma@airborne.aero"><span style="color:blue">michele.toma@airborne.aero</span></a></span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"><a href="www.airborne.aero"><span style="color:blue">www.airborne.aero</span></a></span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:#1F497D"><img border="0" width="133" height="36" id="Picture_x0020_1" src="cid:image001.jpg@01D1F704.E5A76DE0" alt="New Small2"></span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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