ASCII ART - Python

# -*- coding: utf-8 -*-

"""
    Version 1.0
    Code by Delplanque Julien.
    This website help me to understand how the algorithm of conversion work : http://mattmik.com/articles/ascii/ascii.html
"""

import umage
import copy
import platform
import os
import sys

COLOURS = {
    "default"    :    "\033[0m",
    # style
    "bold"       :    "\033[1m",
    "underline"  :    "\033[4m",
    "blink"      :    "\033[5m",
    "reverse"    :    "\033[7m",
    "concealed"  :    "\033[8m",
    # text colors
    "black"      :    "\033[30m",
    "red"        :    "\033[31m",
    "green"      :    "\033[32m",
    "yellow"     :    "\033[33m",
    "blue"       :    "\033[34m",
    "magenta"    :    "\033[35m",
    "cyan"       :    "\033[36m",
    "white"      :    "\033[37m",
    # font colors
    "on_black"   :    "\033[40m",
    "on_red"     :    "\033[41m",
    "on_green"   :    "\033[42m",
    "on_yellow"  :    "\033[43m",
    "on_blue"    :    "\033[44m",
    "on_magenta" :    "\033[45m",
    "on_cyan"    :    "\033[46m",
    "on_white"   :    "\033[47m" }

def style(key):
    """
        Change the style of the output in the shell.
    """
    if (platform.system() != "Windows"):
        sys.stdout.write(COLOURS[key])

def brightness(R,G,B):
    """
        Return the brightness of a RGB triplet.
    """
    return (R+G+B)/3

def chooseCharacter(x,characterSet=['#','@','$','%','x','o','l','i','=','+','<','*','^','~','\"','|',';','-',',','.']):
    """
        Choose a character in the character set according to the brightness x in parameter.
    """
    y = 255/len(characterSet)
    a = len(characterSet)
    b = a-1
    while(b>=0):
        if x<a*y and x >= b*y:
            return characterSet[b]
        else:
            a-=1
            b-=1

def convert(img, step=3):
    """
        Convert a matrix of RGB triplet into a matrix of characters according to the brightness of each pixel.
    """
    image = copy.deepcopy(img)
    mat = []
    for i in range(0,len(image),step):
        matb = []
        for j in range(0,len(image[0]),step):
            bri = 0
            for k in range(i,i+step):
                for l in range(j,j+step):
                    try:
                        R,G,B = image[k][l][0],image[k][l][1],image[k][l][2]
                    except IndexError:
                        R,G,B = 0,0,0
                    bri += brightness(R,G,B)/(step**2)
            s = chooseCharacter(bri)
            matb.append(s)
        mat.append(matb)
    return mat

def convertToString(mat):
    """
        Convert a matrix that contains string into a string.
    """
    s = ""
    for i in range(len(mat)):
        for j in range(len(mat[0])):
            try:
                s += mat[i][j]
            except TypeError:
                pass
        s += "\n"
    return s

def question(s):
    """
        Ask the question in parameter and return True or False according to the user's choice (yes or no).
    """
    f = True
    while(f):
        style("magenta")
        r = raw_input(s+" (Y/n)")
        style("default")
        if(r == "" or r == "y" or r == "yes"):
            return True
        elif(r == "n" or r == "no"):
            return False

def error(message):
    """
        Display the error message in parameter.
    """
    style("red")
    print message
    style("default")

def configuration(inName, outName, precision):
    """
        Display the current configuration according to the parameters.
    """
    if(inName == ""):
        inName = "Not set."
    style("green")
    print "----------Configuration----------\n"
    print "In file name : "+str(inName)
    print "Out file name : "+str(outName)
    print "Precision : "+str(precision)
    print "\n---------------------------------"
    style("default")

def help():
    """
        Display the help message.
    """
    style("green")
    print "------------------------------------Help------------------------------------\n"
    print "i or in             Set the input file."
    print "o or out            Set the output file."
    print "p or precision      Set the precision. 1 = highest precision = 1char/pix"
    print "c or configuration  Show the current configuration."
    print "w or write          Write the text file using the current configuration."
    print "h or help           Show this help message."
    print "q or quit           Quit the application."
    print "cls or clear        Clear the screen."
    print "\n----------------------------------------------------------------------------"
    style("default")

def clearScreen():
    """
        Clear the string according to the os.
    """
    if platform.system() == "Windows":
        os.system("cls")
    elif platform.system() == "Linux" or os.platform() == "darwin":
        os.system("clear")
    else:
        print "Unknown os, no clear screen for you sorry..."

def main():
    style("blue")
    print "------------------------------Image to ascii 1.0----------------------------"
    print "Type h for help."
    style("default")
    inName = ""
    outName = "ascii.txt"
    precision = 3
    f = True
    while(f):
        style("blue")
        s = raw_input("ImToAscii >>> ")
        style("default")
        if(s == "in" or s == "i"):
            inName = raw_input("Enter the name of the input file (.png,.jpg,...) : ")
            if(os.path.isfile(inName) == False):
                inName=""
                error("The input file doesn't exists!")
            else:
                print "Input file set."
        elif(s == "out" or s == "o"):
            outName = raw_input("Enter the name of the output file (.txt) : ")
            txt = outName.find(".txt")
            if(txt == len(outName)-5):
                print "Output file set."
            elif(txt == -1):
                outName = outName+".txt"
        elif(s == "precision" or s == "p"):
            pre = raw_input("Enter the precision you want (must be >= 1, actually "+str(precision)+") : ")
            try:
                temp = int(pre)
                if(temp >= 1):
                    precision = temp
                else:
                    error("You must set the precision as an integer >= 1!")
            except ValueError:
                error("You must set the precision as an integer >= 1!")
        elif(s == "configuration" or s == "c"):
            configuration(inName, outName, precision)
        elif(s == "write" or s == "w"):
            if(inName == ""):
                error("You must set the input file.")
            else:
                configuration(inName, outName, precision)
                b = question("Is that the right configuration?")
                if(b == True):
                    img = umage.load(inName)
                    m = convert(img,precision)
                    st = convertToString(m)
                    fi = open(outName,"w")
                    fi.write(st)
                    fi.close()
                    print "File successfully writed."
        elif(s == "clear" or s == "cls"):
            clearScreen()
        elif(s == "quit" or s == "q"):
            f = False
        else:
            help()

if __name__ == '__main__':
    main()