mosaic with multiple background colors

[kramsden]

I would like to mosaic some tif's but they have two different background colors. Most of them have a black background (0,0,0) but some have a white background (255, 255, 255). Is it possible to select two different background colors so that I can mosaic them all together at once, or should I mosaic one set first and then update the sid with the other set?
Thanks!
Kate

[rparker]

There is no way to set two different background colors. In the end, you will have to change the background of one data set. You can do that in GeoExpress using a shapefile in the Area of Interest tool. Choose the mask outer method and encode with a lossless compression ratio.

[kramsden]

It took me a few steps to get there, but that worked. Thanks. Do you know if I can combine some of these steps? I ended up creating two different sid mosiacs - one with photos that had a white background and one with black background; encoding the mask on the white background; and then mosaicing the two sids together. It looks fine, but ended up taking a long time to do it that way. I also had to reproject the mosaic that had the mask because of an error I got about not being in the same projection as my shapefile, even though they were and I had defined both coordinate systems in ArcCatalog. Regardless - thanks for the workaround.
Kate

[rparker]

GeoExpress 7 has metadata editing capabilities which allow you to define a CRS rather than having to reproject it to define a CRS.

As for combining the process I think it must be done separately since the data background colors are completely different. The mosaic can (and should) only make one color transparent at a time, otherwise you would get undesired results.