topScanning                                                                                  

The most often asked question is 'what resolution should  a print or slide be scanned at?' How long is a piece of string?! It all depends on what your intentions are with the image file.

If you are publishing to the Web, a scan of 72d.p.i. is the standard.

If you are publishing to a quality magazine, 300d.p.i. would be nearer the mark.

If you are printing from your inkjet, 240 - 360d.p.i. is about right.

The above only applies to same-size output as the original. Yes, it gets more complicated! But fortunately you don't have to worry about it.

All I need to know is 1. What physical size do you want the image to be?

                                2. If you are going to print it, the make/model of the printer.

Of course the original can be scanned at different resolutions to suit your needs.

Image File Sizes

These can get enormous and should only be as big as they have to be. A few examples:

A 6" x 4" colour print scanned for same-size output on an inkjet................6.2MB

A 10" x 8"                                 ditto                                           ...............21.0MB

A 35mm slide scanned for A4 output on an inkjet......................................23.0MB

A 6cm x 7cm transparency scanned for 16" x 12" output..........................57.0MB

The above based on a printer input resolution of 300d.p.i. and prior to, if any, file compression.

File Compression

There are two varieties of this system: lossy & lossless. Of the lossy system, the JPG file format is the best known and can compress an image file by a factor of anything between 30:1 and 5:1. Users can set their own quality settings within the software. So long as the highest setting is selected, it has been my experiencw that no image degradation takes place and is the ideal format for transferring images to CD or diskette.

If the intention is to edit the image on your own PC, simply copy to hard disk from the CD and "save as" a non-lossy format such as TIF or BMP.

Lossless file compression comes in the TIF(LZW) flavour and can compress in the ratio of about 10:1. Usually this format is only supported by high-end image editing software so check before you ask for it.

Notwithstanding any of the above, it is your call - your resolution & your file format. I am here to keep my Clients happy!