Black Level Test for Any Display

Gosugadget introduced this black level test which has been on the internet for a while and shared his test results. 

Source: Lagom

The grid of 5x4 squares of shades from 1 (black) to 20 (white) below is what you should be looking at if your display has a good black level. According to Gosugadget, most of displays are supposed to show the bottom 2 rows. 

Source: Gosugadget

Here are the test results on the gadgets he owns and I added a few. 

[TV]
1.  Panasonic VT30 (calibrated)= 1
2.  LG LM9600 (calibrated) = 2
3.  Samsung ES8000 = 6
4.  Sony KDL 40BX450 = 7

[Smart Phone]
1.  Apple iPhone = 2
2.  Samsung Galaxy S2 = 16*(updated)
3.  Samsung Galaxy S3 = 16*(updated)

[Tablet]
1.  Apple iPad = 16*(updated)

[Laptop]
1.  LG Xnote = 3