We are geo referencing a series of scanned historical maps. The map scans are 16 bit tif images which open ok in Photo Shop before referencing.
Once geo refed and rectified the images look ok in ArcMAP but appear all black in PS despite still being 16bit tifs.
The only fix we have found so far is to convert in Arc to an 8 bit tif or jpeg via Raster to New Format. This is ok for general use but we still need original full 16 bit tifs as our master files since some of our users will want the highest resolution an color depth possible fro these maps.
Can anyone tell me why the image shows up ok in Arc but not in PS and how I can get these to display in PS as geo refed 16 bit tifs?
What version of ArcMap your are using? Across versions the NoData handling has changed with ESRI and I suspect it might have something to do with that. Before doing Geo-referencing confirm the pixel depth and then after doing it. Try with a high no data value and see if it resolves the problem
I've been meaning to update this.
The issue was resolved, sort of. It turned out that our original images were not 16 bit as previously thought, they were only 8 bit. ArcGIS, on rectifying, converted them to 16 bit as a result of the no data value being set to 256 by default.
This added an extra color, or an alpha channel, not sure. the result was the image bumped up to 16bit and was also unreadable in PS (although I still don't know why, PS can read 16 bt images). Converting back to 8 but fixes the issue as does manually setting the no pixel value to 0.
I would have assumed Arc to be smart enough to set the defaults based on the input data set, but hey.
Recommendations from others in the field who are doing this same type of work has been to work in a GIS package that handles raster formats better than ArcGIS does, like Global Mapper.
What version of ArcMap your are using? Across versions the NoData handling has changed with ESRI and I suspect it might have something to do with that. Before doing Geo-referencing confirm the pixel depth and then after doing it. Try with a high no data value and see if it resolves the problem
What version of ArcMap your are using? Across versions the NoData handling has changed with ESRI and I suspect it might have something to do with that. Before doing Geo-referencing confirm the pixel depth and then after doing it. Try with a high no data value and see if it resolves the problem
I've been meaning to update this.
The issue was resolved, sort of. It turned out that our original images were not 16 bit as previously thought, they were only 8 bit. ArcGIS, on rectifying, converted them to 16 bit as a result of the no data value being set to 256 by default.
This added an extra color, or an alpha channel, not sure. the result was the image bumped up to 16bit and was also unreadable in PS (although I still don't know why, PS can read 16 bt images). Converting back to 8 but fixes the issue as does manually setting the no pixel value to 0.
I would have assumed Arc to be smart enough to set the defaults based on the input data set, but hey.
Recommendations from others in the field who are doing this same type of work has been to work in a GIS package that handles raster formats better than ArcGIS does, like Global Mapper.
