Netsape and Internet Explorer 4.0 or higher versions only support the image in the process web design of preview option. The image preview option, LOWSRC;attribute gives a preview of the actual image. When the browser comes across this attribute, it loads the LOWSEC image first and then when the entire page has been downloaded the LOWSRC image is replaced by the actual image.
The LOWSRC image is generally and of a lower resolution. The main aim is to give the reader a hint of the actual image that is going to arrive at that given place.
Images for the Web
You can create images for your Web designed page using Paint Shop Pro, Adobe Photoshop or any other image editing software. If you are more comfortable drawing on paper, then you can scan your work using a scanner and then use them for your page. But, most of us may not be good at drawing either on paper or on computer. For those of us there are many freeware and shareware clipart Web sites are well as CDs available in the market.
Here are some popular URLs on the Web where you can get many free images and clipart.
http://www.andyart.com
http://coolarchive.com
http://www.iconbazaar.com
http://www.free-graphics.com
The files size of an of great importance for not only you as a developer but also to the viewer of your Web page. The smaller the size the faster it is downloaded. You must aim to limit the file size to a maximum of 30k. It is important to keep in mind that there are going to be some surfers using slow dial-up  connections or a modem of about 14.4-Kbps.Therefore, while doing Web publishing it is essential to try use images that are small in size
Reducing the file size of an image file
File sizes can be reduced considerably if the pixel dimension of the image is not too large. This adjustment may not be possible in all cases. You should aim as far as possible to create pictures within 170(width) and 113 (height) pixels. There are chances of distortion of the image when the number of pixels is reduced therefore the images to be resized should be very carefully selected .You should avoid images to be resized should be very carefully selected. You should avoid images with thin lines, few details and photographs taken from a long distance. It is safer to consider images with bright; color and a good clear quality for resizing.
Reducing the pixels in an image definitely in most cases reflects on the quality of the image but if they are done with care the quality loss can be inimum.
Decreasing the file size by reducing color depth of an image file
We will look into file size reduction by reducing the color depth in an image. Ideally all graphic files look their best in a 24-bit color resolution. But, this does not work out with the constraints of bandwidth on the Net. It is for this reasons that the GIF file format is so popular.
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