OETF (Opto-Electronic Transfer Function) is a simmilar transfer function to the EOTF. However the OETF represents the transfer function in the encoding process, defining how light intensity in the real world is converted into digital values.

The OETF charactarizes the transformation from captured light via light intensity hitting a camera sensor into corresponding digital values. It’s important to remember, that digital cameras only capture a electrical response to light and encode it digitally. The EOTF is used to convert those digital values back to optical light that is to be emitted by a display.