tiff images totally black

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Level 1

21 points

tiff images totally black

Iʻm using GIS software on my older Mac Pro running the current Yosemite, 10.10.5. After a great deal of effort I finally obtained geotiff files for a USGS set of survey maps from 1928-1930. This was not easy.

The tiff images are totally black - no detail. I have successfully imported many other maps into my GIS system. They all open in Preview or Photoshop or whatever as topo maps, as in maps with lots of details. No matter what I do, these are 100% black.

I obtained these from a person employed in a firm that uses the maps on a Windows platform. Apparently they work fine over there. He simply zipped them and made them available to me on a file server. I unzipped them and - total blackness.

This is an issue I have read about elsewhere. Can anybody suggest a fix?

Thnx!

Mac Pro, Mac OS X (10.6.3)

Posted on Dec 25, 2015 8:59 PM

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Answer 1

Jan Becket Author

Level 1

21 points

Dec 25, 2015 11:32 PM in response to Jan Becket

I found this post on another user group that partially resolves this issue:

http://stackoverflow.com/questions/13925995/options-to-convert-16-bit-image

I opened each image, performed auto levels and then auto contrast. It worked for 14 of the 16 images - not bad. I need all 16, and so this is still not workable for my needs. Two of the 16 maps I need do not respond to auto in the levels dialogue box - they remain totally black.

Suggestions welcome.

- J

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