To test your ability to differentiate between shades of grey, as required by ASME V / SNT-TC-1A and other schemes, follow the instructions below.

Instructions:
On a Computer screen at a distance of 30-50 cm under normal desktop working light conditions, read the numbers in each of the 25 boxes. Count how many of the numbers you are able to read. The click / touch the 'Passing Grade' button.