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Clari-Fi uses blurring to simulate the challenges of viewing small icons, images and text on mobile screens

Understand the calibration to survey data

Several population estimates were provided within the Introduction to mobile screenshots and the Introduction to e-commerce images. These population estimates were derived using data about people's vision from the Better Design Survey (2010). This was a postcode sampled survey of 362 participants, which was conducted inside people's own homes. This survey is particularly relevant for evaluating e-commerce images and mobile screenshots, because it included a handheld vision test chart, and participants were asked to read out the letters of the smallest row that was comfortable for them to read. If the participant usually wore glasses when reading, then they wore them for this test.

For the purpose of calibrating the Check Levels within this tool to population data, the smallest four rows on this chart are of particular interest, and digital versions of these are shown at an enlarged size within the image below.

The different levels of Clari-Fi blurring will now be applied to the digital versions of test chart letters. In each case, the blurring is applied to an enlarged version of these letters, in a calibrated manner that is based on the heights of the corresponding letters within the actual chart.

The biggest row of letters (1.2mm) are the easiest to see, and these pass Check Level AAA, which applies the most severe level of blurring. The remaining rows of letters fail Check Level AAA. Provided the letters are displayed at a reasonably large size, these assessment results don’t change if you move towards or away from your screen, or zoom the letters to become bigger or smaller. The remaining rows of letters are now assessed against Check Level AA.

The 1.0mm letters pass Check Level AA. The remaining rows of letters fail Check Level AA, and are now assessed against Check Level A.

The 0.8 mm and 0.6 mm both pass Check Level A.

We have used these results to calibrate the Check Levels in this tool to the population data from the Better Design Survey. Further information on how this was done can be provided through our training and consultancy services, please contact for details.


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Prices for Clari-Fi Pro licences

Photoshop and PowerPoint versions of Clari-Fi Pro are available to download, and these use the same licence key as the online version.

Prices for individual licences:

  • £250 for a single named user, in perpetuity.
  • £1000 for 10 named users, for 12 months

Prices for 12 month site licenses:

  • £1,000 for an organisation with less than 50 employees
  • £3,000 for an organisation with 50-250 employees
  • £5,000 for an organisation with 250-10,000 employees
  • £10,000 for an organisation with greater than 10,000 employees

All prices are + VAT.

Each of the above licences covers one assessment function (i.e. screenshots or e-commerce images).

Single user licenses can be purchased from our online store. For all other licences, please contact: