如何使用 cv2 在图像上放置文本？

Question

I'm trying to add the text before the time using cv2. Is it possible to add not only time? If so, how can I do this?

from utils import *
import cv2
import numpy as np
from datetime import datetime, timedelta

def get_black_background():
    return np.zeros((500, 500))


start_time = datetime.strptime("2021-01-01", "%Y-%m-%d")
end_time = start_time + timedelta(days=1)


def generate_image_with_text(text):
    image = get_black_background()
    font = cv2.FONT_HERSHEY_SIMPLEX
    cv2.putText(image, text, (int(image.shape[0]*0.35), int(image.shape[1]*0.5)), font, 1.5, (255, 255, 0), 2,
                cv2.LINE_AA)
    return image
    

while start_time < end_time:
    text = convert_time_to_string(start_time)
    image = generate_image_with_text(text)
    cv2.imwrite(f"time_images/{text}.jpg", image)
    start_time += timedelta(minutes=1)

Answer 1

If you alter the content of "text" in generate_image_with_text it will print it. You can call putText with other parameters, say for an upper line (if you mean "above"? the time string?):

beforeTime = "Before Caption![![enter image description here][1]][1]"
upperLineX =  (int(image.shape[0]*0.25) #Adjust multipliers etc. 
upperLineY = (int(image.shape[1]*[![enter image description here][1]][1]0.35)) 
cv2.putText(image, text, (int(image.shape[0]*0.35), int(image.shape[1]*0.5)), font, 1.5, (255, 255, 0), 2, cv2.LINE_AA)

Either add it in that function or put it where it's needed.

If you mean "before" in time, then just check the time however you need and if < etc. call such an alternative text etc.

Also, that code where you create a canvas makes a grayscale one (one channel) and all is white or gray; it should be:

def get_black_background():
    return np.zeros((500, 500, 3)) #3 channels in order to show colors