Image transfer using shared memory in Python

shared_mem_lib.py

import numpy as np
from multiprocessing import shared_memory

# Define global dimensions of 1080 video, would need to change this for a different camera resolution
w, h = 1920, 1080


class SharedMemImagePub:
    def __init__(self):
        # Create a named SharedMemory object
        shm = shared_memory.SharedMemory(
            create=True, name="image_pub", size=w * h * 3
        )

        # Create a Numpy array backed by the SharedMemory
        self.im = np.ndarray((h, w, 3), dtype=np.uint8, buffer=shm.buf)

    def publish_image(self, cv_image):
        # important! self.im = cv_image would not work. We are filling the memory, not reassigning it.
        self.im[:] = cv_image


class SharedMemImageSub:
    def __init__(self):
        self.existing_shm = shared_memory.SharedMemory(name="image_pub")

    def read_image(self):
        im = np.ndarray((h, w, 3), dtype=np.uint8, buffer=self.existing_shm.buf)
        return im