dcraw

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dcraw
DcrawEN.png
dcraw v. 8.99
Original author(s) Dave Coffin
Initial release 5 May 2000; 14 years ago (2000-05-05)[1]
Stable release 9.20 (31 January 2014; 5 months ago (2014-01-31)) [±]
Written in ANSI C
Operating system Cross-platform
Platform Platform independent
Available in English and 11 others
Type RAW decoding software
License GPLv2+
Website dcraw website

dcraw is an open-source computer program which is able to read numerous raw image formats, typically produced by high-end digital cameras. dcraw converts these images into the standard PPM and TIFF image formats. This conversion is sometimes referred to as developing a raw image (by analogy with the process of film development) since it renders raw image sensor data (a "digital negative") into a viewable form.

Development began on February 23, 1997. According to the RCS log version 1.0 was released in revision 1.18, on May 5, 2000. Versions up to 3.15 used the name Canon PowerShot Converter, starting with v3.40 the name was Raw Photo Decoder, switching to Raw Photo Decoder "dcraw" in v5.70. Version 8.86 supported 300 cameras.[1]

Motivation[edit]

While most camera manufacturers supply raw image decoding software for their cameras, this software is almost always proprietary, and often becomes unsupported when a camera model is discontinued. The file formats themselves are often undocumented, and several manufacturers have gone so far as to encrypt all or part of the data in their raw image format, in an attempt to prevent third-party software from accessing it.[2]

Given this ever-expanding plethora of raw image formats, and uncertain and inconsistent support for them by the manufacturers, many photographers worry that their valuable raw images may become unreadable as the applications and operating systems required become obsolete.[3]

In contrast to proprietary decoding software, dcraw strives for simplicity, portability, and consistency, as expressed by its author:

So here is my mission: Write and maintain an ANSI C program that decodes any raw image from any digital camera on any computer running any operating system.

dcraw's open source nature is crucial in assuring this universality: even if its author loses interest in developing the software, or in supporting a particular model of camera, interested users are free to extend it. This helps ensure that it will be possible to decode supported raw image formats far into the future, even after the cameras that produced them are obsolete.

Design[edit]

dcraw is written by Dave Coffin in portable ANSI C. Because many raw image formats are specific to one make or model of camera, dcraw is frequently updated to support new models.

For many proprietary raw image formats, dcraw's source code (based largely on reverse-engineering) is the best—or only—publicly available documentation. dcraw currently supports the raw formats of several hundred cameras (including intentionally obfuscated formats).

dcraw is built around the Unix philosophy. The program is a command line tool which takes a list of raw image files to process, along with any image adjustment options desired. This makes dcraw easy to use from shell scripts, but might be harder in multithreaded scenarios. dcraw also serves as the basis for numerous high-level raw image-processing applications (such as viewers and converters), both free and open source software as well as proprietary software.

GUI frontends[edit]

Several GUI front-ends for dcraw are available. These applications use dcraw as a back-end to do the actual processing of raw images, but present a graphical interface with which to adjust the image processing options.

Multiplatform:

  • darktable, a free RAW developer software for GNU/Linux based operating systems and Mac OS X.
  • iRAW, free GUI based on dcraw.
  • LibRAW DCRAW based library.
  • RawTherapee, a standalone GTK+ raw developer, it uses a tweaked version of dcraw for reading raw photos. It is not just a front-end.
  • UFRaw, a standalone GTK+ application and GIMP plugin.

Unix-like operating systems:

  • Rawstudio, a standalone GTK+ application.
  • dcraw-assist, a KDE-based GUI for dcraw and ImageMagick, supporting ICC-enabled high-quality, web-ready batched RAW conversion.
  • Not So Original, An online image gallery that permits you to manage your workflow and raw photographs with powerful operators.
  • digiKam

Mac OS X:

Microsoft Windows:

  • AZImage Batch and GUI based image converter using LibRAW Lite to read raw formats
  • dcrawnet project on SourceForge is a C# port.
  • DNG Viewer by ideaMK is installed as RAW Image Viewer.
  • EasyHDR uses DCRAW to access RAW files.
  • Helicon Filter, Proprietary, can use dcraw for its raw processing.
  • Konvertor uses DCRAW to access RAW files.
  • RAWDrop, Windows frontend.
  • RawTherapee
  • SNS-HDR uses DCRAW to read RAW files.
  • Zero Noise uses DCRAW as development engine to blend several RAW files into a noise free image with expanded dynamic range ideal for HDR.

References[edit]

  1. ^ a b Dave Coffin (2014). "dcraw.c,v -- complete unabridged RCS file". Retrieved 2014-03-28.  
  2. ^ "Raw storm in a teacup?". Dpreview.com. 2005-04-27. 
  3. ^ Larry Strunk (2006-03-19). "The RAW Problem". OpenRAW. 

External links[edit]

  • schnebeck.de, an Interview with Dave Coffin
  • Raw storm in a teacup? Dpreview.com interviews with Dave Coffin, as he outlines some of the roadblocks to reverse-engineering presented by camera manufacturers.