I have a large Worldview 3 scene that is composed of a panchromatic image and a multispectral image. I am using ENVI modeler to create a layer stack of the pan, multispectral, and some veg indices (e.g. NDVI). I need the resulting stack to be in byte data format (0-255)

At the start of my process the multispectral and pan band images have a no data value of 0. From the multispectral I create the indices I need, then perform a linear percent stretch raster. I also stretch the multispectral band and the pan band, and feed all three of those into an aggregator node. From the aggregator I put them into a "build layer stack" and output the result.

The resulting file does not have a "data ignore value" in the header, and I cannot add one (there is no field) if I try to edit the header information. The areas that were originally "no data" no have a value of either 0 or 255 depending upon the band. I could mask the raster by data values, but I am worried that the 0 or 255 for each band will be inconsistent, and I would like to use this process for other novel images.

So, I am interested in workarounds. Is there another wat to carry the data ignore areas through the process? Could I make an roi out of them somehow at the beginning and mask with that at the end? Thanks.

System info:
ENVI 5.6
Windows 10