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*): 21.8602
Mean of the chroma value (CIE L*a*b*): 8.5461
Image produced by the generic tone mapping operator:
(evalution of the fit via PSNR: PSNR = 37.3032dB)

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: 0.79818
Contrast: 1.694
Low midtone range: 1.5584
High midtone range: 0.98666
Saturation: 0.76927
Frequencies: 0.603, 0.937, 0.987, 0.976, 0.96