[chongli]

You forgot about gamma correction. Before converting a value in the range of 0-255 into a voltage, PCs typically raise that value to the power of 2.2. This makes the difference between small values and large values far more apparent:

2^2.2 = 4.595, 255^2.2 = 196,964.699

[spider-mario]

Differences between small and large values are irrelevant to the point being made here, though. Much more relevant is the difference between nearby values, and the gamma just gets that closer to logarithmic perception, instead of perceptual steps being disproportionately large for small values.

(This may be more apparent when you frame gamma as being applied in the 0-1 range, so it doesn’t really turn 2 into 4.595 and 255 into ~200k; it turns (2/255)≈0.00784 into (2/255)^2.2 ≈ 0.0000233, and leaves (255/255)=1 as is.)