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Digital collecting, photography

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Digital collecting, pictures Matthew Burgess, Digital Collections Analyst @matthewpburgess presented at Digital collecting for NSW public library staff, 27 May 2019

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Digital collecting, photography

  1. 1. @matthewpburgess Digital preservation at the point of acquisition Collecting born-digital photographs Matthew Burgess, Digital Collections Analyst
  2. 2. @matthewpburgess
  3. 3. @matthewpburgess Born-digital photographs • The prevalence of digital cameras makes this one of the fastest growing forms of born-digital content • Custodial emphasis should be placed on appropriate file formats and storage • Care needs to be taken with technical specifications that affect the integrity of the photographs • Acquisitions must be approached on a case-by-case basis, where specifications and standards do not apply to all situations
  4. 4. @matthewpburgess File formats for digital cameras • Low-end cameras and most smartphones will create JPEG, a compressed file format • Some cameras (not many) create TIFF, a file format that can be either compressed or uncompressed • High-end cameras (and some smart phone apps) will create camera raw file formats (often proprietary, eg CR2 for Canon or ARW for Sony) • All cameras that shoot camera raw will also shoot JPEG
  5. 5. @matthewpburgess File formats: JPEG vs camera raw • There are advantages and disadvantages for both • JPEG is a compressed file format • Every time you save a JPEG, information is lost • Small file size, low bit depth • Widely supported, doesn’t require specialist software to view or create copies • Suitable for access • Camera raw contains all of the unprocessed data from the camera sensor • No matter how many times the file is processed, the raw data is never changed • Larger file size, high bit depth • Requires processing by specialist software for access derivatives • Suitable for preservation
  6. 6. @matthewpburgess Digital Negative (DNG) camera raw file format Benefits • Open standard, based on TIFF 6.0 format • Contains raw data from camera sensor • Can have smaller file size compared to TIFF • Self-documenting with embedded XMP and other metadata • Embedded checksum for raw data Risks • Limited support for processing/creating derivatives • Possible corruption when converting from proprietary camera raw file formats • Concerns regarding conversion of hidden (encrypted), proprietary metadata • Still under consideration as an ISO standard
  7. 7. @matthewpburgess What file format should I collect? This depends on various factors: • Does the camera raw file format show the artist’s intent? • Do you want to record the process? • Will the photographer give you the camera raw file?
  8. 8. @matthewpburgess What file format should I collect? • There are different processes that photographers use based on the file format and their own workflows • Their process and workflow determines what you should collect • Questions you might ask: • “Do you only apply your process to the camera raw file?” • “Do you export from camera raw and make adjustments in Photoshop or other programs?”
  9. 9. @matthewpburgess Terminology: bit depth • Bit depth is determined by the number of bits used to define each pixel • The greater the bit depth the greater the number of tones that can be represented • The greater the bit depth, the larger the file size
  10. 10. @matthewpburgess Terminology: bit depth Source: http://www.cambridgeincolour.com/tutorials/bit-depth.htm
  11. 11. @matthewpburgess Terminology: resolution • Resolution = information • Can refer to Dots Per Inch (DPI) or Pixels Per Inch (PPI) • Can refer to the dimensions of an image measured in pixels • The more pixels you have in your image, the larger that image can be reproduced • Pixel dimensions are determined by the camera sensor (megapixels) • Pixel dimensions can be increased in post-production at the cost of image quality
  12. 12. @matthewpburgess Terminology: colour mode & colour profile • Colour mode sets the colour space –eg RGB, CMYK, grayscale • Colour profiles determine how colours/tones are rendered on computer screens and in print • Different colour profiles can represent smaller or larger amounts of colour (eg. sRGB is a smaller profile often used for web, Adobe RGB (1998) is often recommended for preservation) • Camera raw files do not have a colour profile – this is assigned for derivatives (eg JPEG or TIFF)
  13. 13. @matthewpburgess Read about how we developed our specifications and guidelines via http://bit.ly/2EGNMIj
  14. 14. @matthewpburgess

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