What is your OS?
I'm not familiar with sublime-text, but I know how to accomplish this goal in BASH.

sudo apt-get install xclip ImageMagick

This is the most simple form of how to output to image:

xclip -selection clipboard -t image/png -o | convert - output.png

What is your OS?
I'm not familiar with sublime-text, but I know how to accomplish this goal in BASH.

sudo apt-get install xclip ImageMagick

This is the most simple form of how to output to image:

xclip -selection clipboard -t image/png -o | convert - output.png

There's an alternative to pyscreenshot called Pillow.

pip install Pillow

from PIL import ImageGrab

# Grab the image from the clipboard
im = ImageGrab.grabclipboard()

# Check if grab succeeded
if im:
    # Save the image
    im.save("/path/to/save/image.png")
else:
    # Print if the clipboard buffer is not an image
    print("Clipboard buffer is not an image.")

If I had more of an example of how you obtain this image, you might be able to incorporate xclip.

Hopefully Pillow will take care of it.