Cannot save annotated image in matplotlib

Question

I have read every SO thread I could find on this topic, and have read the documentation rather extensively, and even copied and pasted code from these questions/tutorials. But I am still unable to load a jpg, annotate it, and save the figure with matplotlib. I really could use some advice on this topic.

Here is an example of one of my many attempts:

import cv2
import matplotlib.pyplot as plt

image = cv2.imread(...filepath-to-img...)
fig, ax = plt.subplots()
ax.imshow(image)
ax.add_patch(plt.Rectangle(...params...)
plt.savefig(...filepath...)

The image loads correctly, and when I work interactively and run the plt.subplots( and ax.imshow(image) commands, I see a plot with the image pop up, and I get a note saying that it is an AxesImage object.

But when I got to save, it says 'Figure size 432x288 with 0 Axes,' and the resulting image saved to disk is blank.

I've also tried the following for saving to no avail.

my_fig = plt.cgf()
my_fig.savefig(...filepath...)

Basically, it seems that creating a figure and axes, and calling ax.imshow() is not adding the image to my axes, nor are the ax.add_patch() calls doing anything to the axes.

I've also tried it without creating separate axes, as with:

plt.figure()
plt.imshow(image)
my_axes = plt.gca()
my_axes.add_patch(plt.Rectangle(...params...)
plt.savefig(...filepath...)

Again, the resulting figure is blank and has 0 axes.

I know I'm probably missing an obvious step, but I can't figure out what it is, and even copying and pasting code has been no help.

Edit: Adding complete code in response to comment

import cv2
from matplotlib import pyplot as plt

img = './1.png' # 364x364

image = cv2.imread(img)
fig, ax = plt.subplots()
ax.imshow(image)

color = (1, 0, 0, 1)
ax.add_patch(plt.Rectangle((139, 25), 85, 336,
    color = color,
    fill = False,
    linewidth = 2))
plt.savefig('./annotated.png')

Answer 1

I also faced the same problem and here is what worked for me.

from matplotlib.patches import Rectangle
fig,ax = plt.subplots(figsize=(15,12))
ax.imshow(frames[0])
x,y,w,h = bboxes[0]
ax.add_patch(Rectangle((x,y),w,h, linewidth=3, edgecolor='r', facecolor='none'))
plt.axis('off')
plt.savefig("out.png",bbox_inches='tight',pad_inches=0)
plt.show()

I was also getting a blank image on disk when plt.show() was written before plt.savefig()