Dithering is a technique used in computer graphics to create the illusion of color depth in images with a limited color palette (color quantization). In a dithered image, colors not available in the palette are approximated by a diffusion of colored pixels from within the available palette. The human eye perceives the diffusion as a mixture of the colors within it (see color vision). Dithering is analogous to the halftone technique used in printing. Dithered images, particularly those with relatively few colors, can often be distinguished by a characteristic graininess, or speckled appearance.
Reducing the color depth of an image can often have significant visual side-effects. If the original image is a photograph, it is likely to have thousands, or even millions of distinct colors. The process of constraining the available colors to a specific color palette effectively throws away a certain amount of color information.
Figure 1. Original photo; note the smoothness in the detail.
Figure 2. Original image using the web-safe color palette with no dithering applied. Note the large flat areas and loss of detail.
Figure 3. This image also uses the 16-color optimized palette, but the use of dithering helps to reduce banding.
Satish
satish@edit.co.in
No comments:
Post a Comment