Class: FormatParser::CR2Parser

Inherits:
Object
  • Object
show all
Includes:
IOUtils
Defined in:
lib/parsers/cr2_parser.rb

Constant Summary collapse

TIFF_HEADER = 
[0x49, 0x49, 0x2a, 0x00]
CR2_HEADER = 
[0x43, 0x52, 0x02, 0x00]
PREVIEW_ORIENTATION_TAG = 
0x0112
PREVIEW_RESOLUTION_TAG = 
0x011a
PREVIEW_IMAGE_OFFSET_TAG = 
0x0111
PREVIEW_IMAGE_BYTE_COUNT_TAG = 
0x0117
EXIF_OFFSET_TAG = 
0x8769
MAKERNOTE_OFFSET_TAG = 
0x927c
AFINFO_TAG = 
0x0012
AFINFO2_TAG = 
0x0026
CAMERA_MODEL_TAG = 
0x0110
SHOOT_DATE_TAG = 
0x0132
EXPOSURE_TAG = 
0x829a
APERTURE_TAG = 
0x829d

Instance Method Summary collapse

Methods included from IOUtils

#safe_read, #safe_skip

Instance Method Details

#call(io) ⇒ Object 



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# File 'lib/parsers/cr2_parser.rb', line 20

def call(io)
  io = FormatParser::IOConstraint.new(io)

  tiff_header = safe_read(io, 8)

  # Check whether it's a CR2 file
  tiff_bytes = tiff_header[0..3].bytes
  magic_bytes = safe_read(io, 4).unpack('C4')

  return if !magic_bytes.eql?(CR2_HEADER) || !tiff_bytes.eql?(TIFF_HEADER)

  # Offset to IFD #0 where the preview image data is located
  # For more information about CR2 format,
  # see http://lclevy.free.fr/cr2/
  # and https://github.com/lclevy/libcraw2/blob/master/docs/cr2_poster.pdf
  if0_offset = parse_sequence_to_int tiff_header[4..7]

  parse_ifd_0(io, if0_offset)
  set_orientation(io, if0_offset)

  exif_offset = parse_ifd(io, if0_offset, EXIF_OFFSET_TAG)

  set_photo_info(io, exif_offset[0])

  makernote_offset = parse_ifd(io, exif_offset[0], MAKERNOTE_OFFSET_TAG)

  # Old Canon models have CanonAFInfo tags
  # Newer models have CanonAFInfo2 tags instead
  # See https://sno.phy.queensu.ca/~phil/exiftool/TagNames/Canon.html
  af_info = parse_ifd(io, makernote_offset[0], AFINFO2_TAG)
  unless af_info.nil?
    parse_dimensions(io, af_info[0], af_info[1], 8, 10)
  else
    af_info = parse_ifd(io, makernote_offset[0], AFINFO_TAG)
    parse_dimensions(io, af_info[0], af_info[1], 4, 6)
  end

  FormatParser::Image.new(
    format: :cr2,
    width_px: @width,
    height_px: @height,
    orientation: @orientation,
    image_orientation: @image_orientation,
    intrinsics: intrinsics
  )
end