.CR3

Introduction

CR3 is the raw photo format of Canon’s cameras from 2018 onwards, replacing the TIFF-based CR2. It holds the data from the camera’s sensor before any processing, with the camera settings and JPEG previews.

Cameras can save the sensor data with lossless compression or, as C-RAW, with a lossy compression that makes smaller files. Canon has not published the format.

Structure

A CR3 file is not a TIFF file. It uses the ISO base media file format, the box structure of MP4 and HEIF: a series of boxes, each a 4-byte big-endian size and a 4-byte type. The first box is ftyp with the brand crx . A moov box holds Canon’s own boxes with the metadata and a preview, and tracks that point into the mdat box, where the previews and the raw sensor data are stored.

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