MNIST C++ Example with Input from File

Is your feature request related to a problem? Please describe.
Many data scientists and AI engineers are experienced in using TensorFlow or PyTorch in the Python language and want to port their models to C++ for inference. However, many are inexperienced in C++. The MNIST example is good, but it is frustrating that there is not an example that takes an image from a file as input. It is much more likely that someone will want to input an image rather than draw an image and the code will be much shorter and understandable to newcomers.

Describe the solution you'd like
Please can someone provide a new example based on the MNIST C++ example that demonstrates a prediction being made on an image loaded from the disk, as opposed to drawing an image, potentially using OpenCV.

Many thanks

Start by reading the existing c_cxx/MNIST example linked in the issue and see how it currently accepts input. Design the new example around loading an image from disk, potentially using OpenCV, and verify that it produces an MNIST prediction without drawing the image.