9.4. Issues Concerning
Large Images in WML
WAP browsers do not have the horizontal scrolling functionality. So,
they will crop off an image if its width is larger than that of the
wireless device's screen, which means your mobile Internet site may
not look nice and professional to your users. Besides, you have to
remember wireless devices have limited memory. A WAP browser may not
be able to display the image if its size is too large.
following WML example shows how a large image will look on some
mobile phone browsers:
<!DOCTYPE wml PUBLIC
"-//WAPFORUM//DTD WML 1.3//EN"
id="card1" title="Image in WML">
to our WML tutorial.
Mobile Browser 4.0
you can see in the above screenshots, the Sony Ericsson T610 and T68i
mobile phone browsers crop off the sides of a large image while the
Nokia mobile browser allows users to scroll to the right to see the
section off the screen.
issue that you have to concern is that the image size will affect
your mobile Internet site's performance. Also, a larger image will
result in a higher WAP connection cost for those who visit your
mobile Internet site. For example, cellular network operators charge
their GPRS service subscribers by the amount of data transmitted
through their cellular network. The larger the file size, the higher
the service fee.
is essential to optimize the images in your WML documents so as to
keep the image size small. Using the <img> tag's height
and width attributes to scale down an image does not help
since the actual file size of the image is still the same. Here are
some techniques and suggestions for optimizing images:
an image manipulation program like GIMP and Photoshop to scale down
the images, instead of using the height and width
attributes of the <img> tag.
the images are GIF files, you should use a small palette. A smaller
palette can mean lower image quality, so you have to take a balance
between quality and file size.
the images are JPG files, you should save them in a suitable
compression ratio. A higher compression ratio will result in a
smaller file size but a lower quality. So, you have to take a
balance between quality and file size.
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