Checkpoint 5.4 - Core

When height and width are explicitly set, the browser will allocate this space on the browser as it renders the HTML and insert the downloaded image once it makes a separate connection to the server to get it. If these are not set, then the browser will not know what space dimensions to create to insert the image, and will thus cause the browser to re-render the screen image once the images are downloaded. This causes a second flickering of the screen which can interrupt the user's activity.

Images must be resized in a graphics program to the physical dimensions required on the page. It is incorrect to force images to resize by adjusting the height and width attributes of the img element.

Requirement

All images must have the height and width attributes specified in the img element.

Checking Tool

• Internet Explorer - AIS Toolbar: Images > Image List [New Window]
  Check whether size and width of the images are correctly specified in the "Image List" window. If the image height and width were not specified, the program will display "zero" values for image width and height.
• Firefox - Web Developer's Toolbar: Images > Outline Images > Images Without Dimensions