image_resize.py

import os,sys
import Image

size = 256, 256

for (path, dirname,files) in os.walk(sys.argv[1]):
  for f in files:
    ext = os.path.splitext(f)
    upper_ext = ext[1].upper()
    outfile = os.path.join(path, '/root/output', ext[0] + '_256x256' + upper_ext)
    try:
      new_img = Image.new("RGB", (256,256), "white")
      im = Image.open(os.path.join(path,f))
      im.thumbnail(size, Image.ANTIALIAS)
      load_img = im.load()
      load_newimg = new_img.load()
      i_offset = (256 - im.size[0]) / 2
      j_offset = (256 - im.size[1]) / 2
      for i in range(0, im.size[0]):
        for j in range(0, im.size[1]):
          load_newimg[i + i_offset,j + j_offset] = load_img[i,j]

          if(upper_ext == '.JPEG' or upper_ext == '.JPG'):
            new_img.save(outfile, "JPEG")
          elif(upper_ext == '.PNG'):
            new_img.save(outfile, "PNG")
    except IOError:
      print "cannot create thumbnail for '%s'" % os.path.join(path, f)