Interlaced Images

When surfing the Web, you may already have come across images that sharpen progressively as they are downloaded, as shown in Figure 5. This technique gives the viewer a rough impression of the image while it is still downloading. It can be more interesting for the user than being presented with a blank area where the image should be.



Figure 5: An interlaced image (on the left) sharpening progressively until the final display (on the right).

All Web image formats can be interlaced. This option is provided for when saving the file in GIF, JPG or PNG formats. It is often possible to define the number of passes.