6. Slice the remaining layout as per the guidelines, taking care that it should not overlap the earlier sliced parts. A slice image should not overlap another image.

This is a very important aspect as overlapping of various parts of the slices in the layout may later on lead to problems for the html page.

The overall sliced images should not be too small or too big. They should be medium sized as it helps in easy downloading of the layout.

Optimization is a process of fine-tuning the display quality and file size of an image for use on the web. You can optimize images in three major graphic formats used on the web: GIF (Graphics Interchanged Format), JPEG (Joint Photographic Experts Group), and PNG-8 or PNG-24 (Portable Network Graphics, with 8-bit or 24-bit colour).

8-bit is a graphic containing 256 colours. 24-bit is 8-bit x 3, i.e. 256 x 256 x 256 that comes to 16, million colours.

24-bit gives a very fine quality, but increases the file size, which hampers easy downloading of the image. 8-bit is normally used for web applications, as it gives good quality with limited file size.