Canon RAW 2

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(Dumped info from http://libopenraw.freedesktop.org/wiki/Canon_CR2 - I am the author.)
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|formattype=electronic
 
|formattype=electronic
 
|subcat=Cameras and Digital Image Sensors
 
|subcat=Cameras and Digital Image Sensors
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|released=2001
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|extensions={{ext|cr2}}
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|pronom={{PRONOM|fmt/592}}
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|wikidata={{wikidata|Q27866048}}
 
}}
 
}}
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'''Canon RAW 2''' ('''CR2''') is a raw image format used by Canon cameras. It replaced [[Camera Image File Format|CRW]], starting with the 20D, 350D/Digital Rebel Xt and 1D. It was replaced by [[Canon RAW 3]].
  
Formats used by '''Canon''' cameras include:
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== Organization ==
 
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== CRW ==
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CRW, aka [[Camera Image File Format]] is an attempt by Canon to standardise camera files.
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== CR2 ==
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Canon RAW 2 (CR2) came to replace CRW, starting the 20D, 350D/Digital Rebel Xt and 1D.
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=== Organization ===
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Canon CR2 files are TIFF files. All is organised in a TIFF / IFD file.
 
Canon CR2 files are TIFF files. All is organised in a TIFF / IFD file.
  
On of the differenciation with the CR2 files is that they have a header before the IFD0. This does not violate the TIFF spec.  
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On of the differentiation with the CR2 files is that they have a header before the IFD0. This does not violate the TIFF spec.  
  
 
{|
 
{|
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| 0 || 8 || TIFF header
 
| 0 || 8 || TIFF header
 
|-
 
|-
| 8 || 2 || litteral 'CR'
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| 8 || 2 || literal 'CR'
 
|-
 
|-
 
| 10 || 1 || major version (2)  
 
| 10 || 1 || major version (2)  
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Exif is attached to the ExifIFD of IFD0. The CFA data is in IFD3.
 
Exif is attached to the ExifIFD of IFD0. The CFA data is in IFD3.
  
=== Compression ===
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== Compression ==
 
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Canon CR2 files use the old original [[Lossless JPEG (original)|Lossless JPEG]] standard for the RAW data. The same used by [[DNG|Adobe DNG]].
Canon CR2 files use the old original [[Lossless JPEG]] standard for the RAW data. The same used by [[DNG|Adobe DNG]].
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Source: http://www.adobeforums.com/cgi-bin/webx/.3bc36454/0 (link dead)
 
Source: http://www.adobeforums.com/cgi-bin/webx/.3bc36454/0 (link dead)
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The slicing means that the output scanlines have to be reorganised as they are shorter to have a top -> bottom then left -> right, a bit like columns of text. (TODO: do a nice diagram)
 
The slicing means that the output scanlines have to be reorganised as they are shorter to have a top -> bottom then left -> right, a bit like columns of text. (TODO: do a nice diagram)
  
=== Modified files ===
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== Modified files ==
Apparently Canon's proprietary software modifies the RAW file. Other proprietary software seems to choke on said modified files (http://www.prophotohome.com/forum/raw-photo-processing-software-technique/62864-cr2-raws-converted-dpp-wont-open-aperture.html).
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Apparently Canon's proprietary software modifies the RAW file. Other proprietary software seems to choke on said modified files (https://web.archive.org/web/20150512011452/http://www.prophotohome.com/forum/raw-photo-processing-software-technique/62864-cr2-raws-converted-dpp-won-t-open-aperture.html).
  
 
ExifTool has some info:
 
ExifTool has some info:
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* http://www.cpanforum.com/threads/5170
 
* http://www.cpanforum.com/threads/5170
  
=== References ===
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== Sample files ==
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* {{DexvertSamples|image/cr2}}
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== References ==
 
* http://lclevy.free.fr/cr2/
 
* http://lclevy.free.fr/cr2/
 
* http://web.archive.org/web/20061125031802/http://crousseau.free.fr/imgfmt_raw.htm (in French, by one of the developers of DxO) - Using the wayback machine !
 
* http://web.archive.org/web/20061125031802/http://crousseau.free.fr/imgfmt_raw.htm (in French, by one of the developers of DxO) - Using the wayback machine !
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* [https://github.com/lclevy/libcraw2/blob/master/docs/cr2_poster.pdf CR2 format documentation poster]
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* [https://twitter.com/lorenzo2472/status/536569538083844098/photo/1 Format poster image]
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* [http://web.archive.org/web/20140219063611/http://wildtramper.com/sw/cr2/cr2.html Canon's CR2 Raw File Format Specification]
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[[Category:TIFF]]

Latest revision as of 02:56, 28 December 2023

File Format
Name Canon RAW 2
Ontology
Extension(s) .cr2
PRONOM fmt/592
Wikidata ID Q27866048
Released 2001

Canon RAW 2 (CR2) is a raw image format used by Canon cameras. It replaced CRW, starting with the 20D, 350D/Digital Rebel Xt and 1D. It was replaced by Canon RAW 3.

Contents

[edit] Organization

Canon CR2 files are TIFF files. All is organised in a TIFF / IFD file.

On of the differentiation with the CR2 files is that they have a header before the IFD0. This does not violate the TIFF spec.

offset length description
0 8 TIFF header
8 2 literal 'CR'
10 1 major version (2)
11 1 minor version (0)
12 4 (long) for the offset of the IFD3 that contain the RAW data. (in the TIFF byte order)

Exif is attached to the ExifIFD of IFD0. The CFA data is in IFD3.

[edit] Compression

Canon CR2 files use the old original Lossless JPEG standard for the RAW data. The same used by Adobe DNG.

Source: http://www.adobeforums.com/cgi-bin/webx/.3bc36454/0 (link dead)

The width dimension specified in the JPEG stream is actually half the reality because it takes into account 2 channels per sample (the dimension of the CFA pattern).

350D, 5D and 30D files have a different layout. IFD3 (where the CFA is located) has the tag 0xc640 that contains 3 SHORT. 1, x, y. x is the number of column of the first "slice" of the image, y is for the second "slice". I don't know what the 1 mean.

The slicing means that the output scanlines have to be reorganised as they are shorter to have a top -> bottom then left -> right, a bit like columns of text. (TODO: do a nice diagram)

[edit] Modified files

Apparently Canon's proprietary software modifies the RAW file. Other proprietary software seems to choke on said modified files (https://web.archive.org/web/20150512011452/http://www.prophotohome.com/forum/raw-photo-processing-software-technique/62864-cr2-raws-converted-dpp-won-t-open-aperture.html).

ExifTool has some info:

[edit] Sample files

[edit] References

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