Original tone mapped image by iCAM06 {p=33, ct=0.65}:

Histogram of the tone mapped image:

Image statistics of the tone-mapped image:

Median percentile of the lightness (CIE L*a*b*): 33.6412
Mean of the chroma value (CIE L*a*b*): 9.4817
Image produced by the generic tone mapping operator:
(evalution of the fit via PSNR: PSNR = 25.0267dB)

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: 3.8964
Contrast: 0.60471
Low midtone range: 2.1633
High midtone range: 0.78892
Saturation: 0.66274
Frequencies: 1.002, 1.117, 1.318, 1.336, 1.458