This paper proposes a novel inverse TMO, which enables to generate
HDR images from LDR ones,
not only without using any specific parameters but also at low
computing costs.
Furthermore, the inverse TMO has a new characteristic when an
LDR image is mapped from an HDR one by Reinhard's global operator.
In the case, the HDR image reconstructed by the proposed method
without parameters can be remapped into the same image as
that remapped from an HDR one reconstructed with parameters.
Experimental results show that the proposed inverse tone mapping (TM)
operation can be carried out,
while keeping better structural similarity and lower
computing cost than conventional methods.