background-image scaling (CSS)

Dan Corkill writes:

 > BODY {background-image: url(images/background.jpg);  /* 150x400 image */
 >       background-repeat: repeat-y;
 >       background-color: white;}
 > 
 > 
 > When printing a background image, both NS 4.03 and IE4.0, maintain the
 > resolution of the image (JPEG in this particular case) rather scaling
 > the image to maintain the proportions shown on the screen.  So, for
 > example, the image that covers the leftmost 150 pixels of the screen,
 > also only covers the leftmost 150 pixels of the printed document (a
 > very narrow bar at 1200dpi!).
 > 
 > If this is the behavior intended by the CSS specifications

According to the CSS1 specification, the "px" unit is based on a
visual angle similar to a pixel on a typical computer screen. The spec
also suggests that "If the pixel density of the output device is very
different from that of a typical computer display, the UA should
rescale pixel values." [1]. Also, CSS1 spcifies that for replaced
elements (such as IMG), the 'width' and 'height' properties should be
"set to the intrinsic dimensions of the element" [2][3] -- which for
typical web images means pixels. I would therefor say that the
described behavior is not in accordance with CSS1. It would be
interesting to hear from implementors on this issue.

[1] http://www.w3.org/TR/REC-CSS1#length-units
[2] http://www.w3.org/TR/REC-CSS1#width
[3] http://www.w3.org/TR/REC-CSS1#height

Regards,

-h&kon

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