Following is a table with a row for 16 different brightnesses. Across each row are 15 different intensities of numbers, centered on the brightness of the row. In an ideal world you would be able to read all of the text except for the center column, the ones that end in "8", these will match the background exactly. In the real world, human eyes are not that good and your display device may be either low resolution or be poorly adjusted. You will probably see more of the larger text than you do the smaller.

01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f
91 92 93 94 95 96 97 98 99 9a 9b 9c 9d 9e 9f
a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af
b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf
c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf
d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df
e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef
f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd fe ff
01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f
81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f
91 92 93 94 95 96 97 98 99 9a 9b 9c 9d 9e 9f
a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af
b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf
c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf
d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df
e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef
f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd fe ff