Dithering And Its Effects
Dithering is a process by which the infinite colours of any picture which are not available in the browser’s palette are produced by juxtaposing two appropriate available browser colours to form the illusion of a third colour which is only available in the picture. This is a very common method used for reducing the range of colours of the image; 256 or even lesser colours which are seen in the 8 bit *.gif images. It is the same methodology of using a black and white image to display a grey shade by using a combination of black and white pixels.
Dithering has the advantage of reducing the undesirable effects of transferring of function, non-monotonous and indeterminacy. Normally the images are dithered in a randomized pattern as an attempt to reduce harsh transition of colours from one to another. However, the process might reduce the resolution of the picture when printed after dithering. They seem to reduce the sharpness of the image introducing a grainy pattern in the image. To reduce this effect or to overcome this disadvantage of dithering, selective dithering can be used for images, which require dithering by selecting the specific area.
Dithering was introduced and is practiced as web browsers only recognize browser-safe colours and display the colours based on the same. It is neither possible to change any option nor force the browser to display the colours as they are. Once the browser notices a foreign colour, it automatically dithers the image irrespective of the resolution of the outcome it produces. Though, in some cases, it might not be very much noticeable, it might be a problem and not user-friendly for users if the colours of the various commands or navigational buttons are dithered.
As the issue greatly affects the resolution and the quality of the image displayed, designers are normally advised to make use of the browser-safe colours. Other GIF and JPEG graphics can also be used which would be dithered by the browser in a very small percentage. If selection of colours and graphics is done with a little care, the same effect can be got. This is the main philosophy we follow and practice at XEL Web Design. The reputation we have achieved for developing and delivering quality websites in all means includes this factor as well.
