1. DECO1001: Optimising for the Web Format Colour File Size

2. Format Options JPEG: preserves broad colour range and brightness variations of continuous-tone images (photographs or images with gradients) GIF: effective for solid colour images with areas of repetitive colour, supports background transparency (line art, logos, illustrations with type) PNG: effective for solid colour images and perserving sharp detail (line art, illustrations with type)

3. Colour Reduction Algorithms Perceptual: priority to colours for which the human eye has more sensitivity Selective: favours broad areas of colour and the preservation of web colours Adaptive: samples colour that appear most commonly Web: uses the standard 126-colour table common to Windows and Mac palettes, uses no dither Custom: preserves the current colour table as a fixed palette Windows or Mac: uses the default 8-bit colour table, unused colours are discarded

4. Controlling Dither Dither: simulates the appearance of colours not in the colour table, dots of other colours that may be perceived as the missing colour Application dither: photoshop will use dither to simulate colours in the original image that are not in the colour table of the optimised image Browser dither: occurs when a web browser using an 8-bit colour display simulates colours that are in the optimised image that are not web-safe

5. Controlling file size Image size, dpi, 8, 16, 24-bit colour Controlling application dither: a lower percentage of dither creates a smaller file JPEG: controlling quality of image compression (high, medium, low)