I have a bunch of 1 bit rasters (700+) of scanned maps that I need to convert to 8-bit rasters. It's the only way Geosoft will recognize the spatial coordinates of the TIF as they don't deal in 1bit Rasters. The way I have done this in the past is to use the Copy Raster tool and check off the "Convert 1bit to 8bit" option. It has worked well up to this point.

The result I'm getting today is a raster with one value (or no value, depending on how you look at it). The symbology shows 16 as a high and 16 as a low, or sometimes it's 0 and 0. I haven't figured out why the different results, but they are both undesirable.

These raster's are not georeferenced yet.

Does someone else know of a way to do this conversion? Or do they know what checking off this option in the Copy Raster tool does compared to the "Pixel Type" combo box which has a choice for "8_BIT_UNSIGNED"? Any insight would be appreciated.

Edit: Here is an example of the Tif I'm converting, with it's symbology and the symbology of the converted Tif. Screen Capture of ArcMAP 10.0

As you can see, there is definition in the original.

  • Are you sure that the source raster isn't all 1s or all 0s? That would explain the result you're getting. Usually rasters deal with a gradient, but a one-bit raster would either be 1 or 0... not a lot of room for detail. – Mintx Jul 17 '13 at 21:40
  • You're right, it is all 1's and 0's, but usually when I do this the values turn into 255 and 254 respectively. Which seems excessive, but Geosoft Oasis and Target don't work with 1 bit rasters which is why I'm trying to convert them to 8bit. – cndnflyr Jul 17 '13 at 21:55
  • Is it possible that some rasters are all 1s with no 0s? (or vice-versa) If the raster is all one value, I could see problems converting to 8-bit. – Mintx Jul 17 '13 at 22:02
  • No, I'll post an example – cndnflyr Jul 18 '13 at 14:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.