Create pgm_utils.py

examples/pgm_utils.py

@@ -0,0 +1,74 @@
+'''
+pgm_utils.py : Python utilties for PGM files
+             
+Copyright (C) 2014 Simon D. Levy
+
+This code is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as 
+published by the Free Software Foundation, either version 3 of the 
+License, or (at your option) any later version.
+
+This code is distributed in the hope that it will be useful,     
+but WITHOUT ANY WARRANTY without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License 
+along with this code.  If not, see <http://www.gnu.org/licenses/>.
+
+Change log:
+
+20-APR-2014 - Simon D. Levy - Get params from command line
+'''
+
+def pgm_load(filename):
+
+    print('Loading image from file %s...' % filename)
+    
+    fd = open(filename, 'rt')
+    
+    # Skip constant header
+    fd.readline()
+    
+    # Grab image size (assume square)
+    imgsize = [int(tok) for tok in fd.readline().split()]
+        
+    # Start with empty list
+    imglist = []
+    
+    # Read lines and append them to list until done
+    while True:  
+        
+        line = fd.readline()
+        
+        if len(line) == 0:
+            break       
+            
+        imglist.extend([int(tok) for tok in line.split()])   
+
+    fd.close()
+    
+    # Convert list into bytes
+    imgbytes = bytearray(imglist)     
+
+    return imgbytes, imgsize
+    
+def pgm_save(filename, imgbytes, imgsize):    
+    
+    print('\nSaving image to file %s' % filename)
+        
+    output = open(filename, 'wt')
+    
+    output.write('P2\n%d %d 255\n' % imgsize)
+    
+    wid, hgt = imgsize
+    
+    for y in range(hgt):
+        for x in range(wid):
+            output.write('%d ' % imgbytes[y * wid + x])
+        output.write('\n')
+
+    output.close()
+
+     
+