Chapter 14-Designing for the World Wide Web

Overview

Introducing multimedia on the Web.

Designing text for the Web.

Creating images for the Web.

Adding sounds to Web pages.

Creating animation for the Web.

Introducing Multimedia on the Web

Launched in 1989, the World Wide Web was not originally

designed for integrating multimedia.

It was designed as a method of delivering simple text

documents formatted in HTML.

Introducing Multimedia on the Web

Workspace:

The most widely preferred monitor resolution is 800x600.

The usable area of the screen is always smaller than the

monitor’s display area.

Introducing Multimedia on the Web

Nibbling:

Nibbling is an important design principle.

While nibbling, the user has to seek a balance between quality

and available bandwidth.

Introducing Multimedia on the Web

Basics of Hypertext Markup Language (HTML):

HTML is a markup language.

It uses tags to perform functions such as formatting text and

embedding media.

HTML tags are enclosed by angular brackets.

The tags can be written either in upper case or in lower case.

They can be bounding or stand-alone tags.

Introducing Multimedia on the Web

HTML provides tags for inserting media into HTML

documents. These are:

The <IMG> tag for inserting inline images.

The <EMBED> and <OBJECT> tags for embedding

compound documents.

The <APPLET> tags for code.

Designing Text for the Web

User preference in the browser may alter the way text in a

document looks and flows.

Ideally, documents must be designed using Times New

Roman as a proportional font and Courier as the mono-

spaced font.

Designing Text for the Web

OpenType and TrueType are standard methods for

displaying typefaces on the Web.

Cascading style sheet (CSS) available in dynamic HTML

(DHTML) makes font management flexible. It sets text

styles across Web pages.

Designing Text for the Web

The <FONT> tag:

To specify a font, use the FACE attribute of the <FONT> tag.

To specify the font color, use the COLOR attribute.

To set the size of the text, use the SIZE attribute.

Designing Text for the Web

The <TABLE> tag is used for organizing text into columns.

The ALIGN attribute of the <IMG> tag enables text to flow

around an image.

The HSPACE and VSPACE attributes of the <IMG> tag add

space between an image and the surrounding text.

The <BR> tag causes text to begin on a new line.

Creating Images for the Web

All browsers recognize three image formats, GIF, PNG, and

JPEG.

Graphical Interchange File (GIF) images are limited to 8 bits

of color depth (256 colors). It is a commercial image format.

PNG is an open format supported by most image creation

programs.

Joint Photographic Experts Group (JPEG) uses lossy

compression to produce files of size smaller than GIF.

Creating Images for the Web

Creating Images for the Web

GIF versus JPEG.

Adobe Photoshop.

Backgrounds.

GIF Versus JPEG

GIF files are used for line art and images that contain large

areas of the same color.

GIF compresses drawings and cartoons that have only a few

colors in them much better than JPEG.

JPEG can be used for photo-realistic images.

JPEG can compress images at a ratio of even 75:1, but they

compress very slowly.

Adobe Photoshop

It is the most preferred tool for graphic artists.

The native Photoshop format is PSD.

PSD files are in RGB mode that is they use maximum color

depths.

These files are larger in size and contain layers.

Adobe Photoshop

When creating images bound for the Web, use a resolution

of 72 pixels per inch.

Save the original image in a 24-bit loss-less image format.

After image manipulation in the RGB mode, save the source

image as a PSD file.

Changing the mode from RGB Color to Indexed Color

changes the color depths of the image.

Adobe Photoshop

To save an image as a JPEG file, flatten and merge all layers

into a single bitmap.

To save an image as a GIF file, set the mode of the image

to Indexed Color.

To make an image transparent, allow it to float on the

document background. GIF89a formats allow transparency,

while JPEGs do not.

Backgrounds

The <BODY> tag.

Clickable buttons.

Image maps.

The <BODY> Tag

The BGCOLOR attribute sets the background color for a

document.

The TEXT attribute controls the color of the normal text.

The LINK attribute controls the color of an unvisited link.

The VLINK attribute controls the color of a visited link.

The ALINK attribute controls the color of an active link.

Clickable Buttons

A graphic image can be made ‘clickable’ to link to another

document. This is done by including the image tag inside

the bounding tags of an HTML anchor that points to that

document’s URL.

The BORDER attribute of the <IMG> tag should be set to

zero.

Image Maps

Image maps are pictures with defined hot spots that link to

other documents when a user clicks on them.

Web sites display image files using Common Gateway

Interface (CGI) programs.

In client-side image maps, mouse coordinates and their

associated document URLs are included in the client’s HTML

document.

Adding Sounds to Web Pages

Plug-ins allows embedding of sounds into HTML documents.

Internet Explorer offers the <BGSOUND> tag to play an AU,

WAV, or MIDI sound track in a document background.

Netscape and Internet Explorer offer the QuickTime plug-in

for playing AIFF, MIDI, WAV, and AU formats.

Streaming audio is more useful for the Web, where a sound

file can start playing as soon as data begins to download.

Creating Animation for the Web

The <BLINK> and the <MARQUEE> tags provide very

limited dynamism to HTML.

The GIF89a format specification creates simple animations.

It integrates multiple images, or frames, into a single

GIF89a file and displays them with programmable delays

between them.

Creating Animation for the Web

The <IMG> tag is used to embed a GIF89a multiframe

image.

Limit animated GIFs to small images.

Macromedia Shockwave, Director, Flash, and QuickTime are

a few plug-ins used for animation.

Creating Animation for the Web

Plug-ins and players:

Full animation capability became available to Web developers with

the introduction of Macromedia's Shockwave.

Macromedia Flash uses Shockwave to create a .swf (Shockwave

Flash) version of the native .fla file. This enables images to be

displayed on the Web.

While embedding plug-in or player-supported animation files into a

Web page, cross-platform issues should be taken into consideration.

Summary

HTML provides tags for performing varied functions.

The three primary image formats used on the Web are GIF,

PNG, and JPEG.

Images, sounds, and animation can be embedded in an

HTML file.