Percentages for a width/height often give odd behavior. Keep in mind, these
percentages have nothing to do with the size of the image, but on the
current horizontal/vertical space available. So if an image is set for 50%,
and the current width of the object it is in is not set, or it has
collapsed, then the image won't be visible. But if the table cell is 50% of
the page, then the image would have a width of 50% of the table cell or %25
of the page.
Most people don't use percentage widths for images because they behave
oddly, and may have varying degrees of support among the browser vendors.
Also, because the percentages are based upon space available and not the
initial size of the object, their appearance can warp as a width=50% and a
height=50% does not mean scale the object to 50% in each dimension, but use
50% of the available space in each dimension. Because the space
availablility can be different in each dimension warping is a definite
possibiity.
