Biorad images, in general, are only readable "as is" by the Bio-rad operating
system software (COMOS or SOM).  You can, of course, strip the 76 byte header
from them and read the raw digital values into other programs to reconstruct the
image.  Subsequently, the images can be re-saved as TIFF or PICT images from
NIH-Image, Photoshop or other image image processing programs.
 
Merged images are another matter as each image of the pair is scaled to 4 bits,
then the two are combined into a 8 bit image.  (This is my understanding at any
rate.)
 
A better way to do this is to load each image into Adobe Photoshop (or similar
16-bit or higher image processing program) by importing the images as "raw"
images, giving the width and height and using "76" as the byte size of the
header to be skipped (often called 'offset').
 
By loading your red image into the red channel of the RGB mode, and loading your
green image into the green channel of the RGB mode, and setting the blue channel
to black, you can display both images at 8 bits each for a total 16 bit image,
thus avoiding the loss of half your data.
 
Subsequently, this full bit depth image can be saved in Photoshop as a TIFF file
and exported to any high-quality dye sublimation printer or slide maker.
Alternately, a photo of the screen wth a long enough exposure time to catch the
alternate scans can be just as high quality.
 
There are, I believe, programs such as WIN-MERGE and others which merge the
Bio-Rad files into full bit-depth files readable by Photoshop.  Perhaps someone
else can comment on those programs as I've not used them myself.
 
Charles Thomas
Integrated Microscopy Resource
UW-Madison
608-263-6288