I already got few replies regarding this issue but I still haven't solved and I don't even have the slightest idea what's causing it.

I tried mogrify, convert using ImageMagick, none of them works still giving me the following errors when after loading contact map & pdb file on
Contact Map Visualizer Plugin.

Any idea at all please let me know. 

Error: 1
<type 'exceptions.ValueError'> Exception in Tk callback
Function: <function <lambda> at 0xa180cdc> (type: <type 'function'>)
Args: ()
Traceback (innermost last):
File "/usr/lib/python2.7/dist-packages/Pmw/Pmw_1_3/lib/PmwBase.py", line 1747, in __call__
return apply(self.func, args)
File "/usr/lib/pymodules/python2.7/pmg_tk/startup/contact_map_visualizer.py", line 54, in <lambda>
self.menuBar.addmenuitem('Plugin', 'command','Contact Map Visualizer',label = 'Contact Map Visualizer',command = lambda s=self : getImageLocation(s))
File "/usr/lib/pymodules/python2.7/pmg_tk/startup/contact_map_visualizer.py", line 68, in getImageLocation
File "/usr/lib/pymodules/python2.7/pmg_tk/startup/contact_map_visualizer.py", line 83, in getPDBLocation
loadImageOnScreen(self.file.name, self.pdbFile.name)
File "/usr/lib/pymodules/python2.7/pmg_tk/startup/contact_map_visualizer.py", line 118, in loadImageOnScreen
im = Image.open(image_file)
File "/usr/lib/python2.7/dist-packages/PIL/Image.py", line 1976, in open
return factory(fp, filename)
File "/usr/lib/python2.7/dist-packages/PIL/ImageFile.py", line 91, in __init__
File "/usr/lib/python2.7/dist-packages/PIL/XpmImagePlugin.py", line 93, in _open
raise ValueError, "cannot read this XPM file"
<type 'exceptions.ValueError'>: cannot read this XPM file

Many thanks,