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Can someone please tell me what this purple anomaly is on the imagery that we just received. The only thing I have done processing wise is to build the pyramids when they first came into ArcMap. Other than that, I have not done anything. I also should add that the purple dissapears when zoomed in to an extent past 1:10000, and gets larger as you zoom out. Any help would be great. Thanksalt text

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Could it be something to do with the rgb colours?, and for anyone who needs clarification, it is a TIFF image. Thanks... –  Andrew Dec 1 '10 at 21:50

2 Answers 2

up vote 4 down vote accepted

I would certainly go back to the original image and try rebuilding the pyramids. The fact that it disappears when zooming in to me means it's a pyramid issue. If it persists in ArcMap, do as @scw says, and try GDAL.

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Thanks for that. Re-building the pyramids gave me a much cleaner image, and everything looks great. –  Andrew Dec 2 '10 at 14:03

I can't specifically address why ArcGIS overviews are creating the purple block, but perhaps try creating overviews with GDAL on a copy of the file, and see if the artifact persists:

gdaladdo --config USE_RRD YES input.tif 2 4 8 16
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I also tried this process, and it worked as well, so thanks!! –  Andrew Dec 2 '10 at 14:04

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