Image data processing method and recording apparatus allowing original image of broad dynamic range to be reproduced

Abstract

An image data processing method transforms a picture signal having a broad dynamic range to another picture signal having a narrow dynamic range. The picture signal having the narrow dynamic range is subjected to inverse transform to thereby output a recovered signal having the broad dynamic range. A difference between the original picture signal and the recovered signal, both having the broad dynamic range, is produced and then stored in a recording medium as difference data. A parameter for software processing to be executed for reproduction of the original picture signal later is also stored in the recording medium. In this way, the method can transform the original data with the broad dynamic range to the data of a standard file format with the narrow dynamic range, record the transformed data, and allow the original data to be recovered and effectively used later, as desired.