How we test scanners

Scanning quality

35mm slides for use in a scanner

We test how well each scanner scans a range of media, including slides

We assess the quality of each scanner by scanning a range of media including a page of black-and-white text, a magazine page and (where applicable) mounted slides. 

To really challenge the scanners, we use a slide with a lot of detail and depth, as well as one with a dark area at the bottom. Some scanning software could mistakenly interpret this as the edge of the slide and crop it off.

We use the scanner’s default settings in our test.

Our experts rate the quality of each scan looking, for example, at clarity, the level of detail reproduced and the accuracy of the colours.

Scanner speed

Each scan is timed so we can rate the speed of every scanner. Our latest test includes timings for film and slide scans.

Depth of field test

We test the extent to which each scanner can effectively scan a three-dimensional object (we use two watches in our test). This measures how well the scanner is able to interpret and accurately scan objects that are not flush against the glass plate of the device (known as depth of field). 

Our experts time how long each scan takes and rate the quality of the resulting scan.

OCR scanner software

In May 2008 we started testing Optical Character Recognition (OCR) software, which most scanners now come with. This automatically detects the text in your scanned document and converts it into a text file so you can edit it. 

We tested the supplied software to see how it would cope with a magazine page including a mixture of words and pictures. Models tested before May 2008 won't have a rating for OCR software.

Ease of use

We assess how easy each scanner is to install straight out of the box including loading the accompanying software. We look at how easy the lid of the scanner is to open and whether it’s removable so you can scan something bulky. 

We also assess how straightforward it is to load slides and film strips into the accompanying adaptors for scanning.