<p>When ENVI considers a pixel with a "no data" value, it doesn't consider the pixel to not exist. It still recognizes that there is a pixel there. It just doesn't use the value from that pixel in some processing. So, the logic is that pixels with "no data" values are still in the image. That is why layer stacking includes those areas.&nbsp;</p> <p>You would need to perhaps create a subset that does not include the "no data" pixels, and use that as input to the layer stacking.</p> <p>- Peg</p>