ImageDraw renders TrueType characters too skinny on 16-bit grayscale images compared to RGB ones #5591
Description
What did you do?
I tried to render a line of text on a 16-bit grayscale image using a TrueType font and the ImageDraw module.
What did you expect to happen?
I expected the shape of characters to be determined only by the actual font file and size, both of which I specified when initializing an instance of ImageFont.FreeTypeFont.
What actually happened?
For some reason the characters appear very skinny compared to the same line of text being rendered with the same font over an RGB image of the same size.
What are your OS, Python and Pillow versions?
- OS: Linux
- Python: 3.6
- Pillow: 8.1.1
import numpy as np
from PIL import Image, ImageDraw, ImageFont
image_height = 500
image_width = 700
grayscale_image_array = np.ones([image_height, image_width]).astype(np.uint16)
grayscale_image_array[0:500, 0:700] = 12000
grayscale_image = Image.fromarray(grayscale_image_array)
rgb_image_array = np.ones([image_height, image_width]).astype(np.uint8)
rgb_image_array[0:500, 0:700] = 47 # roughly same color as on `grayscale_image`
rgb_image = Image.fromarray(rgb_image_array)
font_data = ImageFont.truetype('assets/ProductSans-Regular-prehint.ttf', 50)
grayscale_draw = ImageDraw.Draw(grayscale_image)
grayscale_draw.text((300, 300), "Expected normal-width characters", fill='white', font=font_data)
rgb_draw = ImageDraw.Draw(rgb_image)
rgb_draw.text((300, 300), "Expected normal-width characters", fill='white', font=font_data)Grayscale image:
RGB image:
ProductSans-Regular-prehint.ttf
(to test locally, change ".gif" extension of this file to ".ttf" as GitHub doesn't allow to upload those directly)
