Original tone mapped image by Camera {x=small, c=1.8}:

Histogram of the tone mapped image:

Image statistics of the tone-mapped image:

Median percentile of the lightness (CIE L*a*b*): 7.2512
Mean of the chroma value (CIE L*a*b*): 5.0509
Image produced by the generic tone mapping operator:
(evalution of the fit via PSNR: PSNR = 36.0703dB)

Fitted tone curve of the generic tone mapping operator,
compared to the luminance compression done by the tone mapping operator:

Fitted parameters of the generic tmo:

Exposure: 4.1883
Contrast: 1.7027
Low midtone range: 1.6366
High midtone range: 1.0644
Saturation: 0.76967
Frequencies: 0.191, 0.836, 0.993, 0.999, 1.006