REXReader v0001
This program is made with Livecode Community Edition 6.0.2
You can open the included "REXReaderv0001.livecode" file and edit
the user interface or scripts if you like.

Click the "Convert 320x200 REXPaint" button
Select an image exported by REXPaint that uses the Aquarius Computer custom ROM font.
320x200 and 640x400 screens are supported
 
The file will be processed and a text file with the BASIC program with POKES and
characters will be save in the same location.
The program doesn't recognize or write the  color data.

The program is very slow.
About two minutes to cover the 1000 character locations.
 
The BASIC output is for the Aquarius Computer System, and can be pasted into 
the default BASIC of the Virtual Aquarius or the MESS.
The DATA can be used in other BASICs by converting using this formula:
N is the number of pairs of DATA to read
D is the  total number of character locations from the origin (0,0)
C is the ascii character code

Read N 
for i = 1 to N
read D,C
REM put the cursor D positions away from screen 0,0
REM print, put, poke, ascii character C
next i

There's a script to read REXpaints Font images and convert them to 
strings of binary ones and zeros in a button on the stack.
Not the focus of the program, but necessary to get what it does done,
and it was what I was trying to figure out a day earlier. :D

Everything is public domain do what you want with this.