If the image file name ends with the suffix ".Z" then its compressed. It can be uncompressed by just double clicking on the file. A window will open, wait a couple of seconds, and then the close the window. The original file, for example "1.map.Z" would then become "1.map".

However if you would prefer the image files not to be compressed in the first place, you can do the following:
    1) Open the file manager.
    2) Go to the directory:
                 /opt/epma/conf/soft/
    3) Find the file called
                 icon_compress
    4) Change its name to
                 icon_compress.NOT
Now all future image files will not be compressed.