Download time
A Thousand words will download a lot faster that a small image. Think of a
single character as a byte, so 1000 chars=1k
Image Value
This is a major consideration, crop or reduce the picture size so it contains
the best compromise of information/junk
Alt tags
An image on a web page should have an alt tag, height and width sizes. The
alt tag can be displayed as a tool tip but the main purpose of the alt tag is
to label the space for browsers with graphics disabled. The width and height
attributes allow the browser to lay the page out before it renders the text,
to prevent the page from jumping.
If you need to include large graphics consider using a thumbnail image that
is linked to your large graphic.