.ARW

Introduction

ARW is the raw photo format of Sony’s Alpha cameras and some of its compact cameras. It holds the data from the camera’s sensor before any processing, with the camera settings and a JPEG preview.

Sony has not published the format. Depending on the camera and its settings, the sensor data is stored compressed with some loss, uncompressed, or with lossless compression. Older Sony cameras used the related .srf and .sr2 formats.

Structure

An ARW file is a little-endian TIFF file: it starts with 49 49 2A 00 (II*) and a chain of image file directories (IFDs) of tags. These point to the JPEG previews, the Exif data with Sony’s maker note, and the raw sensor data.

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