how can I mosaic a 16 bit image with an 8 bit image?

[HarrietMcQuade]

Hi There,

I have approx 20 .tiff images, 18 of those are 8 bit unsigned but 2 of them are 16 bit unsigned. I need to mosaic all of these images together to create one raster. I have mosaiced the 18, but when i try to add the 2 16 bit images the whole image turns black? Is there anyway this can be done?

Cheers
Harriet

[TimothyHales]

If your image is displaying black, it is probably from the symbology being used.  If you are using a stretched renderer, then the values are being stretch from 0 to 65535 as apposed to 0 to 255.  If the majority of your values are on the lower end then they will display as black.  You might try adjusting the stretch using the Min/Max stretch type or even use a unique values or classified renderer.

As for the mosaic process, you could either convert the 8 bit raster to 16 bit using the Copy Raster tool and then mosaic, or you could use the Mosaic to New Raster tool and set the output Pixel Type to 16 bit.

[GordonSumerling]

G'day Harriet,

There is a really good discusion around managing imagery collections at the following web page: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009t000001vr000000. It discusses multi-bit dept imagery and multi-resolution imagery.

The recommended work flow is to create a mosaic for each source of image formatd and then combine them together in a derived mosaic dataset containing three bands. This one will be used to provide the best color imagery combination for all input images.

Hope this helps
Gordon