Can I import a graphic and add to it?

edit

Thank you! This seems very promising. I used your code to try to add a red line on top of my image:

var('x')
p = plot(x,-2,2,color='red',aspect_ratio=1, figsize=12.3)
p.save('test.png')
import PIL
img = PIL.Image.open('pic.png')
img2 = PIL.Image.open('test.png')
img3 = PIL.Image.blend(img,img2,alpha=0.7)

I adjusted the figsize of the line image to be 12.3 so that it matches my "pic" image, and both images are 906 x 906. However, I still get the following error:

ValueError: images do not match

Do you have any suggestions? When I run just

img.show()

or

img2.show()

each associated image opens as a bmp in a separate window, so it seems that the files are treated equally.

You can resize an image. See PIL or PILLOW documentation.

...
img2 = img2.resize(img.size)
img3 = PIL.Image.blend(img,img2,alpha=0.7)