testpillow.py

from PIL import Image, ImageDraw, ImageFont

sourceFileName = "fsafa.jpg"
avatar = Image.open(sourceFileName)
drawAvatar = ImageDraw.Draw(avatar)

xSize, ySize = avatar.size
fontSize = min(xSize, ySize) // 11

myFont = ImageFont.truetype("/Library/Fonts/OsakaMono.ttf", fontSize)

drawAvatar.text([0.9 * xSize, 0.1 * ySize - fontSize], "32", fill=(255, 0, 0), font=myFont)
del drawAvatar

avatar.show()