These few lines gives a quick control on the image size in case you don't want a full width or full screen image. You create the MD image as below to resize the image by 50% for instance:

This will create the below img tag in HTML. The @50% will be truncated from the caption, but it will be still present in the ALT. You can use whatever size after the @ between 1 and 100. Then the integer has to be followed by %.