0.39% is the change from 255 to 256
Calculation steps:
[( 256 - 255 ) ÷ 255] x 100 = 0.39%
Formula
Percentage change = [(256 - 255) / 255] x 100
Subtract the new number by the original number
256 - 255 = 1
1 ÷ 255 = 0.00392156862745098
0.00392156862745098 x 100 = 0.39%