ascii.py

'''
This Module turns an image into ascii.

1. Make Dict of Images for each character
2. Take in Image to Convert
    - take in image piece.
3. Run image piece against char dict with smallest difference.
4. Print char image with smallest difference to console.

'''
from PIL import Image, ImageChops, ImageStat, ImageOps

def resize_image(im):
    '''
    this takes in an image and blows it up so that it will fit an 80 character string
    '''
    im_w = im.size[0]
    im_h = im.size[1]

    new_im_height = (im_h * 640)/im_w
    new_height_rem = new_im_height%12
    new_im_height = new_im_height - new_height_rem

    im = ImageOps.fit(im,(640, new_im_height),Image.ANTIALIAS)
    return im

def char_dict():
    '''
    takes char images and appends them to
    '''
    chars = dict()
    for i in range(32,127):
        im = Image.open('images/fonts/'+str(i)+'.png')
        im = im.convert("L")
        chars[i] = im
    return chars

def image_list(file):
    '''
    Constructs list of 8px x 12px greyscale pieces from input image
    (In order from top left to bottom right as you would read a document in most languages)
    '''
    im = Image.open(file)
    im = resize_image(im)
    im = im.convert("L")
    im = ImageOps.autocontrast(im)
    im = ImageOps.equalize(im)
    images = []
    yo = 0
    for y in range(im.size[1]/12):
        xo = 0
        for x in range(im.size[0]/8):
            image_piece = im.crop((xo,yo,8*(x+1),12*(y+1)))
            images.append(image_piece)
            xo += 8
        yo +=12
    return images

def image_diff(filename):
    '''
    image_string: ascii characters of a given line of an image
    image_lines:
    '''
    image_string = ""
    image_lines = []
    t = 0
    for im in image_list(filename):
        current_key = 2
        chars = char_dict()
        diff_old = 5000
        for key, char_im in chars.iteritems():
            diff_im = ImageChops.difference(im,char_im)
            stat_im = ImageStat.Stat(diff_im)

            diff_var = stat_im.mean[0]

            if diff_var < diff_old:
                diff_old = diff_var
                current_key = key
        image_string += chr(current_key)
        t+=1
        if t == 80: #
            print image_string
            line = image_string
            image_lines.append(line)
            image_string = ""
            t=0
    return image_lines