Designing Images and Sound for Mobile Devices

SDK Documentation for Windows Mobile-Based Smartphones

Images and sounds can make the user experience more appealing and should be used when they add value for the user. However, when developing online content for a mobile device, remember that connectivity and bandwidth are limited and expensive compared to a desktop computer. In addition, the display area is much smaller and is easily cluttered. Therefore, to support a better user experience, a conservative approach with images is recommended.

Note Omitting unnecessary images also improves download times. Wide-area wireless data networks commonly range from 9.6 Kbps to 19.2 Kbps maximum throughput.

Images

If you want to display an image that is larger than the working area, Pocket Internet Explorer follows these rules:

If Fit to Screen is off, Pocket Internet Explorer displays the image as specified with the <img> tag, honoring the height and width attributes or by using the natural image size when no attributes are specified.
If Fit to Screen is on, the way the image appears depends on its size, the available width within the block element that contains the image, and the current text size setting as follows:
- If the width of the image is smaller than or equal to the available width within its container, for example, a table cell or the <BODY> element, the image is displayed as specified in the <img> tag.
- If the image is wider than its container, the image is shrunk to fit exactly within the container. The original width of the image determines how much the image can be scaled down to fit in the container; wider images are allowed to shrink to a smaller percentage of their original size than are narrower images. Under no circumstances can an image be wider than the screen width of the device.
- The "text size" setting affects the allowable percentage reduction from the image's original size. A smaller text size setting allows greater reduction.

Scaling reduces the quality of many images, so you might consider avoiding images wider than the smallest supported viewing area.

Supported Image Formats

Pocket Internet Explorer supports the following formats natively:

PNG
JPEG
GIF
Animated GIF files
WBMP (displayed only in WML)
BMP

Additional formats can be added through third-party software.

Image Maps

Pocket Internet Explorer supports image maps. Remember to keep your images small and simple. In addition, your image should convey to the user some indication of its function.

Sound

Background sounds are supported by Pocket Internet Explorer and can provide interesting effects. The exact codec and sample rates supported can vary among manufacturers. To maximize compatibility and minimize download size, use of a raw Pulse Code Modulation (PCM) stream with a single channel (mono), 8 bits of resolution, and a sample rate of 11 KHz is recommended.

Note BGSOUND files play only once. The LOOP attribute is not supported.

Images

Supported Image Formats

Image Maps

Sound

See Also