img_to_ascii.py

# Python code to convert an image to ASCII image. 
import sys, random, argparse 
import numpy as np 
import math 
  
from PIL import Image 
  
# gray scale level values from:  
# http://paulbourke.net/dataformats/asciiart/ 
  
# 70 levels of gray 
gscale1 = "$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\|()1{}[]?-_+~<>i!lI;:,\"^`'. "
  
# 10 levels of gray 
gscale2 = '@%#*+=-:. '
  
def getAverageL(image): 
  
    """ 
    Given PIL Image, return average value of grayscale value 
    """
    # get image as numpy array 
    im = np.array(image) 
  
    # get shape 
    w,h = im.shape 
  
    # get average 
    return np.average(im.reshape(w*h)) 
  
def covertImageToAscii(fileName, cols, scale, moreLevels): 
    """ 
    Given Image and dims (rows, cols) returns an m*n list of Images  
    """
    # declare globals 
    global gscale1, gscale2 
  
    # open image and convert to grayscale 
    image = Image.open(fileName).convert('L') 
  
    # store dimensions 
    W, H = image.size[0], image.size[1] 
    print("input image dims: %d x %d" % (W, H)) 
  
    # compute width of tile 
    w = W/cols 
  
    # compute tile height based on aspect ratio and scale 
    h = w/scale 
  
    # compute number of rows 
    rows = int(H/h) 
      
    print("cols: %d, rows: %d" % (cols, rows)) 
    print("tile dims: %d x %d" % (w, h)) 
  
    # check if image size is too small 
    if cols > W or rows > H: 
        print("Image too small for specified cols!") 
        exit(0) 
  
    # ascii image is a list of character strings 
    aimg = [] 
    # generate list of dimensions 
    for j in range(rows): 
        y1 = int(j*h) 
        y2 = int((j+1)*h) 
  
        # correct last tile 
        if j == rows-1: 
            y2 = H 
  
        # append an empty string 
        aimg.append("") 
  
        for i in range(cols): 
  
            # crop image to tile 
            x1 = int(i*w) 
            x2 = int((i+1)*w) 
  
            # correct last tile 
            if i == cols-1: 
                x2 = W 
  
            # crop image to extract tile 
            img = image.crop((x1, y1, x2, y2)) 
  
            # get average luminance 
            avg = int(getAverageL(img)) 
  
            # look up ascii char 
            if moreLevels: 
                gsval = gscale1[int((avg*69)/255)] 
            else: 
                gsval = gscale2[int((avg*9)/255)] 
  
            # append ascii char to string 
            aimg[j] += gsval 
      
    # return txt image 
    return aimg 
  
# main() function 
def main(): 
    # create parser 
    descStr = "This program converts an image into ASCII art."
    parser = argparse.ArgumentParser(description=descStr) 
    # add expected arguments 
    parser.add_argument('--file', dest='imgFile', required=True) 
    parser.add_argument('--scale', dest='scale', required=False) 
    parser.add_argument('--out', dest='outFile', required=False) 
    parser.add_argument('--cols', dest='cols', required=False) 
    parser.add_argument('--morelevels',dest='moreLevels',action='store_true') 
  
    # parse args 
    args = parser.parse_args() 
    
    imgFile = args.imgFile 
  
    # set output file 
    outFile = 'out.txt'
    if args.outFile: 
        outFile = args.outFile 
  
    # set scale default as 0.43 which suits 
    # a Courier font 
    scale = 0.43
    if args.scale: 
        scale = float(args.scale) 
  
    # set cols 
    cols = 80
    if args.cols: 
        cols = int(args.cols) 
  
    print('generating ASCII art...') 
    # convert image to ascii txt 
    aimg = covertImageToAscii(imgFile, cols, scale, args.moreLevels) 
  
    # open file 
    f = open(outFile, 'w') 
  
    # write to file 
    for row in aimg: 
        f.write(row + '\n') 
  
    # cleanup 
    f.close() 
    print("ASCII art written to %s" % outFile) 
  
# call main 
if __name__ == '__main__': 
    main()