One can source images on a webpage with usual urls:
<img src="some-image-url" >
or,
with data uris:
<img src="data:......." > // data:[<mediatype>][;base64],<data>
That is similar to having a script inside the HTML document or having a script linked with a script tag with the script's url.
Does second one makes page use much more memory, since it has lots of string data in the document
in the img tags' src attributes?