Use of Logarithmic Non-Linear Transfer Characteristic for Transmission of Linear Signals through Limited-Bit-Depth Image Representations and Interfaces

Published by	Publication Date	Number of Pages
SMPTE	01/18/2007		4

Category: SMPTE

Description

SMPTE RDD 2 – Use of Logarithmic Non-Linear Transfer Characteristic for Transmission of Linear Signals through Limited-Bit-Depth Image Representations and Interfaces

This document describes a method of connecting the 12-bit linear processing space in an electronic capturecamera to a downstream 12-bit linear processing space (“virtual camera processing”) via a pair of industrystandard10-bit serial interfaces carrying 10-bit signal representations. This is achieved by means of a nonlineartransfer curve to be applied to the linearly-coded source image signal and a reverse function by meansof which the non-linearity may be accurately reversed (forward and reverse lookup tables may also be usedas an implementation alternative to the functions). By exploiting both human visual system characteristics andthe particular noise characteristics of the camera, the non-linear curve prevents the bit-depth reduction havingany perceptible effects on the received image.

By specifying a particular transfer curve and reverse function, interchange between multiple providers andusers of source and destination equipment can be achieved.