watermark text over images using Python with PIL and textwrap, by tweaking the widths you can control the max length of text allowed and it also does the word wrap and shows extra text in next line

overlay_text_over_image.py

from PIL import Image
from PIL import ImageFont
from PIL import ImageDraw
import textwrap

base_image_location = "/home/aameer/Desktop/test.png" #base image location
W,H=(900, 100) #width and height of base image
font_location = "/home/aameer/Desktop/verdanab.ttf" #font used
output_image_location='/home/aameer/Desktop/' #location where output file will be stored


def create_watermark_image(text):
    #allowing one line of 35 chars and based on our height  
    #we can fine tune to accomodate different number of lines thus total chars limit too
    para = textwrap.wrap(text,width=35)
    #white
    text_color=(0, 0, 0,64)
    text_font = ImageFont.truetype(font_location,33)
    image = Image.open(base_image_location)
    d = ImageDraw.Draw(image)
    #padding and height for the lines breaking the text into several lines
    current_h, pad = 20, 2
    for line in para:
        w, h = d.textsize(line, font=text_font)
        d.text(((W - w) / 2, current_h), line, fill=text_color,font=text_font)
        current_h += h + pad 
    image.save(output_image_location+'overlayedimage.png')