> From: Moose <olymoose@xxxxxxxxx>
>
> I have no idea how JPEG compression works inside. For all I know, it
> uses a nonlinear, base two, mapping and the quality levels are setting
> the number of steps per stop.
It's considerably more complicated than that. It does a discrete
cosine transform on 8x8 blocks, re-quantizing the result.
You're thinking of colour spaces, which map pixel values to
luminosity, also known as gamma. Gamma is the exponent used to come up
with the non-linear curve. The 2.2 gamma typically used by computer
monitors results in packing about 11 stops into 8 bits.
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