img2ascii.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')
	print(type(image))

	# 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()