Convert grayscale to rgb

To convert a grayscale image to an RGB image, you can use the following steps:

1. Load the grayscale image.
2. Create a new RGB image with the same size as the grayscale image.
3. Copy the grayscale image to all three color channels of the new RGB image.
4. Save the new RGB image.

Here is an example code snippet in Python using the OpenCV library:

import cv2

# Load the grayscale image
gray_img = cv2.imread('grayscale_image.jpg', cv2.IMREAD_GRAYSCALE)

# Create a new RGB image
rgb_img = cv2.cvtColor(gray_img, cv2.COLOR_GRAY2RGB)

# Save the new RGB image
cv2.imwrite('rgb_image.jpg', rgb_img)

In this example, we first load the grayscale image using the `cv2.imread()` function with the flag `cv2.IMREAD_GRAYSCALE`. Then, we create a new RGB image by converting the grayscale image to RGB using the `cv2.cvtColor()` function with the flag `cv2.COLOR_GRAY2RGB`. Finally, we save the new RGB image using the `cv2.imwrite()` function.