This is the second in a sequence of videos about images. It begins by reviewing the impact of resolution (pixel density) and colour depth (the number of bits used to encoded the colour of each pixel) on the quality of an image. It goes on the explain that a true colour 24 bit RGB bitmap encodes the amounts of red, green and blue separately for each pixel, using 8 bits per colour channel. The video continues with an explanation of indexed colour bitmaps, which can result in good quality images with much smaller files sizes. The role of a colour table known as a palette is described. Adaptive palettes and web safe palettes are also mentioned, as is the need for dithering (also known as colour quantisation) to simulate colours that might not be available in the palette.