drewnoakes/metadata-extractor

Support Canon CRW camera RAW format

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#2 opened on Nov 19, 2014

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format-camera-rawhelp wanted

Description

The older CRW file format (superseded by CR2) is treated as a TIFF file, however it does not meet the library's expectations of TIFF files.

When TiffMetadataReader attempts to verify them, it falls over with ExifReader expecting 49492a but getting 49491a due to the difference in file format.

CRW data is stored as CIFF (Camera Image File Format) which is similar to TIFF, but differs.

Specifications at:

http://www.sno.phy.queensu.ca/~phil/exiftool/canon_raw.html

(Migrated from Google Code issue 42)

Contributor guide

Tech stack
java
Domain
backenddata
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Javaunderstanding of Exif/CIFF formatshexadecimal byte readingmetadata extractor codebase familiarity
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Examine how TiffMetadataReader processes files, then implement a new reader for CRW/CIFF format using the linked specifications. The CIFF header bytes differ (49491a vs 49492a). Create a new metadata reader class for CRW and integrate it into the metadata extraction pipeline. Test with sample CRW files.