DCRaw

Dcraw ( after the initials of the programmer Dave Coffin ) is a free program to convert the raw images of digital cameras. It can process the mostly proprietary, inadequate or non- documented image formats almost all digital cameras on the market.

Formation

Starting point and the occasion was the emergence of high-quality, most digital SLR cameras, as JFIF files also allowed for the direct storage in raw format in addition to saving the captured images. The benefits of working with images in RAW files are located in the further processing and correction possibilities (eg the White Balance ) and the larger dynamic range of lossless 14 - or 12 -bit data to the lossy 8 -bit JPEG images. The major disadvantage is that all camera manufacturers use different, mutually incompatible and divergent even within a production series formats for their raw images. Some of the information is also encrypted or obfuscated to hinder unauthorized access.

For all of these cameras are of the manufacturers (possibly in addition to acquiring ) offered programs that can read their raw formats and convert. These, however, have two shortcomings: Firstly, these are consistently about proprietary software, ie non-free applications that can also be used on only one acceptable to the manufacturer of the operating system or hardware platform. Related to this is the second problem: If a camera is taken off the market because a successor appears, the manufacturer gives the series or completely disappears, the support for these programs expire either immediately or after a certain time. There is no guarantee or requirement that the function necessary for that camera raw conversion software into those for a different camera or a successor is picked. Now the device associated operating system - hardware combination out of use, it is no longer possible to use the raw images from the camera.

To remedy this shortcoming, was dcraw: A free, easy to use as possible, portables, as many cameras as possible and supportive, the Unix philosophy following, exactly one task fulfilling program. dcraw is a command line program, the names of the processed raw images and their settings are passed as command line parameters. dcraw outputs the converted images in either TIFF or PPM format on the standard output, so the result can be easily processed and easy dcraw be integrated into shell scripts.

Use

Although possible, and in some scenarios also useful dcraw is not usually used directly. This is also provided to the program functions as the back end, which performs the conversion of the raw data; all other machine vision and possibly processing steps are then carried out by the actual application program. In addition to specializing in the raw data conversion programs, such as UFRaw or rawstudio that dcraw does not call wait, but its source code are directly involved, this also countless others, both free and proprietary machine vision and processing programs as well as image databases and special applications, for example, for evaluation of the images from surveillance cameras or astronomical photography.

Examples

Dcraw can make only converts a number of other other raw data processing. General Exif information, as used eg camera, aperture, focal length and exposure time can be determined as follows:

Dcraw -v -i IMG_1234.RAW Most raw formats contain an embedded JPEG preview. This can be extracted in the file IMG_1234.thumb.jpg:

Dcraw -e IMG_1234.RAW Without additional parameters, the actual conversion in the binary-coded 8-bit PPM file IMG_1234.ppm done:

Dcraw IMG_1234.RAW One, for example, suitable for further processing with GIMP or CinePaint PNG file can be generated simply by means of a pipe NetPBM:

Dcraw -4 -c IMG_1234.RAW | pnmtopng > IMG_1234.png TIFF files can create dcraw directly:

Dcraw - T -6 IMG_1234.RAW Supported cameras

According to the website (as of July 2012), the current version supports raw formats from 474 cameras, a large proportion of all ever produced in any significant quantity digital cameras, including all models of the two market counterparties Nikon and Canon. Add to this the generic support for Adobe's Digital Negative format and all cameras that produce this.

Software, using the code of dcraw

  • DigiKam
  • FixFoto
  • Helicon Filter
  • Imabas
  • Lightroom
  • LightZone
  • Picture Window Pro
  • Photivo
  • PhotoLine
  • PTGui
  • RawShooter
  • RawTherapee
  • UFRaw
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