EXPLORE: Using a flatbed scanner

Popular scanning software

At http://www.scantips.com is a run through of some popular scanning software.

More scanner settings:

Bits per channel
In most cases, RGB (24-bit) images contain 8 bits of data for each of 3 colour channels. This translates as (2 to the power of 8) colours/channel, or a total of 256 cubed (millions of colours).

Many scanners now permit scanning at an even greater bit depth ­ up to 12 or 16 bits/channel (36- or 48-bit colour). This is useful for very high quality photographic work, or for print output at large sizes, but for most general use is not needed. The files created are much larger than regular 24-bit files, and they are more difficult to manipulate (many Photoshop functions, for example, are not compatible with images that contain higher than 8-bits/channel).

Unless you have a particular reason not to do so, leave this setting at 8-bits/channel.

Descreening
Images from books and magazines have been through a printing process which renders the images as a collection of tiny dots. In B/W printing this is called a 'halftone', in colour printing it is 'colour screening' or '4-colour separation'. When these images are scanned, the frequency of printing dots can react with the screen pixel resolution, to create a 'moire' effect, which gives the impression of viewing the image through a patterned screen.

Most scanning software now includes a 'descreen' filter, which allows you to choose a setting for coarse (eg newsprint), medium (eg magazine) or fine (eg art print) printing screens. This does quite a good job of counteracting the moire effect.

Sharpening
Some software supports image sharpening. If you do not have another means of sharpening the image (in your image editing software), this may be useful. Unsharp mask is the most effective tool, the use of it is explained in Image manipulation.

If you use the sharpening tool in the scanning software, try out the effect carefully ­ some images benefit more from sharpening than others.