diff --git a/sprite-optimizer.py b/sprite-optimizer.py
index f82a73e..63c6c1f 100755
--- a/sprite-optimizer.py
+++ b/sprite-optimizer.py
@@ -1,5 +1,16 @@
 #!/usr/bin/env python3
 
+### Readme ###################################################################
+# name: sprite-optimizer
+# version: 1.1
+# author: Dark-Storm
+# license: CeCILL v2.1
+#
+# comments:
+# lines are stored as arrays of pixels
+##############################################################################
+
+
 from argparse import ArgumentParser
 from bresenham import bresenham
 from PIL import Image, ImageDraw
@@ -7,12 +18,12 @@ from random import randint
 import sys
 from time import time
 
-
 rand = lambda: randint(0,200)
 progress = False
 
 
 def print_stats(img):
+	"""Print number and percentage of black pixels"""
 	pixels = img.getdata()
 	count = sum([1 for i in pixels if i == 0])
 	if progress:
@@ -20,6 +31,7 @@ def print_stats(img):
 
 
 def get_lines(img):
+	"""Generate all potential lines the image contains"""
 	lines = []
 	pixels = [(x, y) for x in range(img.width) for y in range(img.height) if img.getpixel((x, y)) == 0]
 
@@ -27,6 +39,7 @@ def get_lines(img):
 
 	if progress:
 		print("Get lines:", end = "")
+	# for each pair of pixels, get the line
 	for a in pixels:
 		for b in pixels:
 			line = list(bresenham(a[0], a[1], b[0], b[1]))
@@ -35,6 +48,7 @@ def get_lines(img):
 				if p not in pixels:
 					is_in = False
 					break
+			# if image contains the line, put it on the array
 			if is_in:
 				lines.append(line)
 			i += 1
@@ -49,11 +63,15 @@ def get_lines(img):
 
 
 def removing_doubles(lines):
+	"""Remove lines that are symetric"""
 	results = []
 	n = len(lines)
 
 	if progress:
 		print("Remove duplicated lines:", end = "")
+	# for each line, see if it's already in the output array
+	# beware not to change the orientation of the line (bresenham is not symetric)
+	# TODO: optimize a bit this operation
 	for i, l in enumerate(lines):
 		s = sorted(l)
 		same = False
@@ -74,18 +92,23 @@ def removing_doubles(lines):
 
 
 def removing_useless(lines):
+	"""Remove lines that are sub-lines of other ones"""
 	results = []
 	n = len(lines)
 
 	if progress:
 		print("Remove useless lines:", end = "")
+	# for each line, see if there is a line that contains every pixel of it
 	for i, l in enumerate(lines):
 		inclusions = 0
+		# others are all lines that are not l
 		others = (x for x in lines if x != l)
 		for k in others:
 			if len(list(set(l).intersection(set(k)))) == len(l):
 				inclusions += 1
 				break
+		# or len(l) == 1 : we keep single pixels to complete the image if necessary
+		# TODO: do some tests to see if it's worth or not
 		if inclusions == 0 or len(l) == 1:
 			results.append((len(l), l))
 		if progress:
@@ -99,16 +122,22 @@ def removing_useless(lines):
 
 
 def get_best_solution(img, lines):
+	"""Compute an optimized solution. The magic part of the algorithm"""
 	px_left = [(x, y) for x in range(img.width) for y in range(img.height) if img.getpixel((x, y)) == 0]
 	results = []
 	n = len(px_left)
 
 	if progress:
 		print("Draw:", end = "")
+	# while the entier image has not been drown
 	while len(px_left):
+		# define the length of lines
 		lines = [(sum([1 for p in l if p in px_left]) - len(l)/(2*max(img.size)), l) for n, l in lines]
+		# sort them by length
 		lines = sorted(lines)
+		# pop the longest
 		(p, line) = lines.pop()
+		# define the pixels that are not covered by any lines
 		px_left = [p for p in px_left if p not in line]
 		results.append((line[0], line[-1]))
 		if progress:
@@ -122,13 +151,16 @@ def get_best_solution(img, lines):
 
 
 def generate_code(lines, args):
+	"""Generate Basic Casio code"""
 	str_x, str_y = "{", "{"
 
-	for (xa, ya), (x, y) in lines:
-		x, y = x + int(args.offset[0]), y + int(args.offset[1])
-		xa, ya = xa + int(args.offset[0]), ya + int(args.offset[1])
-		str_x += "{}, ".format(get_coord(x, xa))
-		str_y += "{}, ".format(get_coord(y, ya))
+	# Casio's bresenham is reversed compared to classic ones
+	# so we need to reverse the ends of the lines
+	for (x_end, y_end), (x_start, y_start) in lines:
+		x_start, y_start = x_start + int(args.offset[0]), y_start + int(args.offset[1])
+		x_end, y_end = x_end + int(args.offset[0]), y_end + int(args.offset[1])
+		str_x += "{}, ".format(get_coord(x_start, x_end))
+		str_y += "{}, ".format(get_coord(y_start, y_end))
 
 	str_x = str_x[:-2] + "}"
 	str_y = str_y[:-2] + "}"
@@ -138,6 +170,7 @@ def generate_code(lines, args):
 
 # From Zezeombye's BIDE
 def get_coord(start, end):
+	"""Convert a pair of coordonates to the appropriate x+yT  Multi DrawStat output"""
 	result = "";
 	if start != 0:
 		result += str(start)