|
Actual photos of displayed text and x-height in pixels
|
logMAR
|
Snellen
|
Character x-height (mm)
|
Minimum required screen pixels/inch (ppi)
|
|---|
|
Theoretical
|
Measured
|
Error %
|
|---|
|
63 pixels
|
1.3
|
6/120
|
11.56
|
11.33
|
2.11
|
10.99
|
|
50 pixels
|
1.2
|
6/95
|
9.18
|
9.99
|
2.19
|
13.83
|
|
40 pixels
|
1.1
|
6/76
|
7.30
|
7.19
|
1.50
|
17.40
|
|
32 pixels
|
1.0
|
6/60
|
5.80
|
5.75
|
0.79
|
21.90
|
|
25 pixels
|
0.9
|
6/48
|
4.61
|
4.50
|
2.43
|
27.54
|
|
21 pixels
|
0.8
|
6/38
|
3.66
|
3.78
|
3.19
|
34.66
|
|
0.7
|
6/30
|
2.91
|
2.70
|
7.21
|
43.64
|
|
0.6
|
6/24
|
2.3
|
2.16
|
6.55
|
54.98
|
|
0.5
|
6/20
|
1.84
|
1.80
|
1.96
|
69.13
|
|
0.4
|
6/15
|
1.46
|
1.44
|
1.26
|
86.98
|
|
0.3
|
6/12
|
1.16
|
1.08
|
6.77
|
109.48
|
|
0.2
|
6/10
|
0.92
|
0.90
|
2.19
|
138.37
|
|
Too small character for useful display with the specific screen
|
0.1
|
6/8
|
0.73
|
N/A
|
N/A
|
175.17
|
|
0.0
|
6/6
|
0.58
|
N/A
|
N/A
|
218.97
|
|
-0.1
|
6/4.8
|
0.46
|
N/A
|
N/A
|
273.71
|
|
-0.2
|
6/3.8
|
0.37
|
N/A
|
N/A
|
346.19
|
|
-0.3
|
6/3
|
0.29
|
N/A
|
N/A
|
437.93
|
- ppi pixels per inch, N/A not applicable
