Scanned TIFF pixelated in ArcGIS

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10-17-2013 10:57 AM
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by Anonymous User
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Original User: dkwiens

I've scanned a pile of historical air photos (they look fine in my photo preview software, picture 1), but when I bring them into ArcMap and build pyramids, they become extremely pixelated (picture 2). Any ideas?
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If the rasters are one bit, then the issue is probably with the conversion of one bit to the copy or the pyramids that are 8 bit.  You can also look at the pyramids and the resampling method.
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by Anonymous User
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Original User: dkwiens

Thanks for the reply, Jeff. The rasters are 1 bit (in ArcGIS, at least), which I take to mean 0,1. How do I: a) change the bit depth, if they are already 1 bit, or b) fix this with the resampling method? I'm confused whether I need to re-scan the photos with different settings, or if I can fix this with ArcGIS settings/tools.

edit: building pyramids using either bilinear or cubic interpolation methods did not work.

update: with help from Customer Support, we figured out that if I use a brand new copy of the image (which has never had nearest pyramids built) and then build bilinear resampled pyramids, it works. Seems pretty random, hopefully this helps someone else...
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Glad that worked out.  As a former Support Analyst, I have used this technique before.  Since tifs can be created from a multitude of programs and there is a standard published, there are still instances that the best technique is to save the raster over in ArcMap and then see if it displays better.  Also bilinear pyramids are always seem to do better with 1 bit rasters.
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