The highest contrast ratio of the Acer H257HU is 100000000:1. That's over twenty times the contrast ratio of a 5000000:1 PC screen, which is the most frequently found contrast ratio.
A 100000000:1 dynamic contrast ratio is actually the best contrast ratio amongst all PC screens that have been on the market for a similar time to the H257HU.
A Mega Contrast dynamic contrast ratio is the worst contrast ratio across similar types of PC screen.
It may also be worth also looking at one of the alternative PC screens that have a 100000000:1 dynamic contrast ratio currently available including the G257HU ($221.99), or the H277H ($269.99) both from Acer which is cheaper; or the Acer B286HK ($305.99) which has a better Rating.