There are few issues related with images and graphics which one must take account of before undertaking professional web design using images. It takes time to download graphic files since they are relatively larger than the text files. It may take several seconds to few minutes while a graphics file downloads.
Search engines cannot process images. Search engines like Yahoo, Dog Pile etc cannot index images referenced by an html document. Thus search engines would not be able to find the documents easily. Many users do not have graphical browsers. Also internet explorer and Netscape users might disable inline images to open web pages faster.
Color images are not always portable. Am image that may appear reasonably good on web page might look distorted or otherwise not correct on other system. So choosing the correct graphics file format for professional web design is very important. There are many image formats available today but images such as GIF, JPEG, PCX, PNG, WMF etc are more popular than others.
When creating images for use in an HTML document one must always try to restrict himself to GIF or JPEG formats only. Since these two image formats are widely supported by web browsers. Every file format has advantages and drawbacks. While one format may download faster another format may deliver images with more detail.
When we choose a graphics file format, the most important point to remember is download speed versus image quality. If download time is the main criteria then we can keep file size low by choosing JPEG images whereas, if the image details are more important we can use GIF files. GIF files provide good compression if the image contains only a few colors. GIF files support a maximum of two hundred and fifty six colors and JPEG supports 16.7 million or true colors. Thus if color depth is not important then one can just use GIF files and if we want to maintain quality and color depth JPEG files should be used.
An image looses its details if it is saved using schemes that loose energy but if loss less compression schemes are used the details of an image are not lost. However schemes which loose energy give much higher compression ratios. So in professional web design file format must be chosen wisely.
If we do not restrict our self to JPEG or GIF formats while choosing our graphic images then the web browser may require external programs or helper applications called plug ins to display our graphics which is not a good way for professional web design. PNG formats are not used these days in professional web design as they are not supported by majority of web browsers.
