When I copy a portion of a TIFF image with the REM options and then merge that copy back into the original raster the copy will grow in pixels. I have also noticed that the copy will shift down and to the right during the merge process. I have tried this in both Raster Design 2005 and Raster Design 2006 with the same results. The one difference I did notice between the two is that in RD 2005 the image shifts down and to the right. When I merge the image back in RD 2006 it shifts to the left and up. I can duplicate this with the electrical.tiff image that is supplied as a sample image with Raster Design.
Ideas are greatly appreciated on this.