system PAUSE system PAUSE - 5 months ago 34
CSS Question

When to use IMG vs. CSS background-image?

In what situations is it more appropriate to use an HTML

IMG
tag to display an image, as opposed to a CSS
background-image
, and vice-versa?

Factors may include accessibility, browser support, dynamic content, or any kind of technical limits or usability principles.

Answer

Proper uses of IMG

  1. Use IMG if you intend to have people print your page and you want the image to be included by default. —JayTee
  2. Use IMG (with alt text) when the image has an important semantic meaning, such as a warning icon. This ensures that the meaning of the image can be communicated in all user-agents, including screen readers.

Pragmatic uses of IMG

  1. Use IMG if you intend to have people print your page and you want the image to be included by default. —JayTee
  2. Use IMG if you rely on browser scaling to render an image in proportion to text size.
  3. Use IMG for multiple overlay images in IE6.
  4. Use IMG with a z-index in order to stretch a background image to fill its entire window.
    Note, this is no longer true with CSS3 background-size; see #6 below.
  5. Using img instead of background-image can dramatically improve performance of animations over a background.

When to use CSS background-image

  1. Use CSS background images if the image is not part of the content. —sanchothefat
  2. Use CSS background images when doing image-replacement of text eg. paragraphs/headers. —sanchothefat
  3. Use background-image if you intend to have people print your page and you do not want the image to be included by default. —JayTee
  4. Use background-image if you need to improve download times, as with CSS sprites.
  5. Use background-image if you need for only a portion of the image to be visible, as with CSS sprites.
  6. Use background-image with background-size:cover in order to stretch a background image to fill its entire window.