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To be viewed or printed a RAW image is typically converted to a Raster graphics format. This processing involves a number of operations:

Raw image format Color filter array tone mapping


To be viewed or printed, the output from a camera sensor is typically converted to a Raster graphics format such as JPEG. This processing involves a number of operations:

Note that demosaicing is only performed for CFA sensors, it is not required for 3CCD or foveon sensors.

Cameras and image processing software may also perform additional processing to improve image quality, for example:

When a camera saves a raw file it defers most of this processing, typically the only processing performed is the removal of defective pixels (the DNG specification requires that defective pixels are removed [1]). Some camera manufacturers do additional processing before saving raw file, for example Nikon has been criticized by astrophotographers for applying noise reduction before saving the raw file.[2]

Some raw formats also allow nonlinear quantization[3][4].

File contents[edit]

Raw files contain, by necessity, the information required to produce a RGB format file from the camera's sensor data. Although there is no standard raw file format, the structure of raw files often follows a standard pattern, that is:

  • a short file header which typically contains the byte-ordering of the file, a file identifier and an offset into the main file data
  • camera sensor metadata including the size of the sensor, and its color profile
  • image metadata including the exposure time and other EXIF data
  • an image thumbnail
  • optionally a reduced size image in JPEG format
  • the sensor data

Additionally many raw formats (including 3FR(Hasselblad), DCR,K25,KDC(Kodak), CR2(Canon), ERF(Epson), MEF,MOS(Mamiya), NEF(Nikon), ORF(Olympus), PEF(Pentax), RAW,RW2(Panasonic) and ARW,SRF,SR2(Sony)) are TIFF-based [5]

Adobe digital negative format is an extension of the TIFF 6.0 format.[6]

  1. ^ "Digital Negative (DNG) Specification" (PDF). pp. p. 14. 
  2. ^ "Comparative test: Canon 10D / Nikon D70 in the field of deep-sky astronomy". 
  3. ^ "Digital Negative (DNG) Specification" (PDF). Adobe Systems. 2008-04. pp. p. 61.  Check date values in: |date= (help)
  4. ^ "Is the Nikon D70 NEF (RAW) format truly lossless?". 
  5. ^ "Exif Tool, Supported File Types". 
  6. ^ "Digital Negative (DNG) Specification" (PDF). Adobe Systems. 2008-04. pp. p. x.  Check date values in: |date= (help)