Small refactoring and added simple CLI

pzr.py

from PIL import Image
import sys


def addUnique(l,item):
	if item not in l:
		l.append(item)
	return l

def convertImage(image):
	#Open image
	im = Image.open(image)
	pix = im.load()

	#first create the legend
	# Creates a list containing 5 lists initialized to 0
	out_l_l = [[0 for x in range(im.size[0])] for x in range(im.size[1])] 
	col_set = []

	for j in range(im.size[0]):
		for i in range(im.size[1]):
			r, g, b, a = pix[i,j]
			curPixel = '#%02x%02x%02x' % (r, g, b)
			if a != 0:
				addUnique(col_set, curPixel)

	line = ""
	for item in col_set:
		line += item + " "
	print(line)

	for j in range (im.size[0]):
		line = ""
		for i in range (im.size[1]):
			r,g,b,a = pix[i,j]
			if (a == 0):
				line += "."
			else:
				curPixel = '#%02x%02x%02x' % (r, g, b)
				line += str(col_set.index(curPixel))
		print(line)
#Entry module
if __name__ == "__main__":
	if (len(sys.argv) == 2):
		convertImage(sys.argv[1])
	else:
		print("Usage: <file>")