Do you ever heard of
PLACEHOLD.IT ? A quick and simple image placeholder service. How does it work?
Just put your image size after our URL and you’ll get a placeholder.
You can also use it in your code, like this:
You will get a image placeholder like below:
But markdown does not support defining the height and width for the image.
so you can choose to use
<image> tag if need.
Is it very simple and useful? Have fun!