To solve the problem of a conventional image signal processing apparatus, including gamma correction processing, for executing nonlinear conversion wherein gamma correction results in increasing the noise component contained in image signal, when signal level resides in a region where the inclination of the conversion characteristic is large.
An input signal is respectively given to LPFs 40, 42 whose transmission characteristics differ from each other, a selector 44 selects outputs from the LPFs and gives the selected output to a gamma correction circuit. A filter control circuit 32 controls the switching of the selector 44. A comparator 60 of the filter control circuit 32 compares the signal level of an object pixel with threshold R. When the signal level of the object pixel belongs to a region where the inclination of the conversion characteristics is large and the signal level is smaller than the threshold R, the selector 44 is controlled to select the output of the LPF 42 whose cut-off frequency is lower than that of the LPF 40 and whose noise component elimination effect is larger than that of the LPF 40.
NAKAI TOMOMICHI
NAKAKUKI TOSHIAKI
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