What Simon Linked to:

"The width and height attributes on applet, embed, iframe, img, object or video 
elements, and input elements with a type attribute in the Image Button state, 
map to the dimension properties 'width' and 'height' on the element 
respectively."

"When the text below says that an attribute attribute on an element element 
maps to the dimension property (or properties) properties, it means that if 
element has an attribute attribute set, and parsing that attribute's value 
using the rules for parsing dimension values doesn't generate an error, then 
the user agent is expected to use the parsed dimension as the value for a 
presentational hint for properties, with the value given as a pixel length if 
the dimension was an integer, and with the value given as a percentage if the 
dimension was a percentage."

"The rules for parsing dimension values are as given in the following 
algorithm. When invoked, the steps must be followed in the order given, 
aborting at the first step that returns a value. This algorithm will return 
either a number greater than or equal to 1.0, or an error; if a number is 
returned, then it is further categorized as either a percentage or a length."

There is a note on the preceeding paragraph stating it is Ready for first 
Implementations and that is dated 10/23/2009

"Some rules are intended for the author-level zero-specificity presentational 
hints part of the CSS cascade; these are explicitly called out as 
presentational hints."

"When an img element is available, it provides a paint source whose width is 
the image's intrinsic width, whose height is the image's intrinsic height, and 
whose appearance is the intrinsic appearance of the image."

So, it seems img's width and height being "intrinsic values" are meant to tell 
the browser what the actual width and height of the specified image is UNLESS 
the type attribute is set to ImageButton in which case percentage will be used 
but the image will be a button.

However, the paint source is CSS-able and therefore you can scale the image via 
CSS.

I'm not sure whether I want to be right about that or not. Being right means I 
read and followed the spec and that can't be healthy ;).  If I got it wrong 
please forgive me I can only read English fluidly ;)

Art C.
 

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