Class: DicomS::Transfer

Inherits:
Object
  • Object
show all
Extended by:
Support
Includes:
Support
Defined in:
lib/dicoms/transfer.rb

Overview

Base class for Transfer strategy classes that define how the values of DICOM pixels are scales to be used as image pixels or to be processed as data (generic presentation values).

Different strategies determine how much of the original data dynamic range is preserved.

All the Transfer-derived classes can pass an :output option to the base which changes output range limits from what is stored in the DICOM. Two values are supported:

  • :byte Output consist of single byte values (0-255)

  • :unsigned Output is always unsigned

The method min_max(sequence) of each class returns the minimum and maximum values which are mapped to the output limits. These values may be raw or rescaled depending on the min_max_rescaled? method

Direct Known Subclasses

RangeTransfer, WindowTransfer

Constant Summary collapse

USE_DATA = 
false
FLOAT_MAPPING = 
true

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Support

assign_dicom_pixels, cast_metadata, decode_vector, define_transfer, dicom?, dicom_bit_depth, dicom_compression, dicom_element_value, dicom_name_pattern, dicom_narray, dicom_rescale_intercept, dicom_rescale_slope, dicom_signed?, dicom_stored_bits, dicom_window_center, dicom_window_width, encode_vector, find_dicom_files, keeping_path, normalized_path, output_file_name, pixel_value_range, single_dicom_metadata

Constructor Details

#initialize(options = {}) ⇒ Transfer

Returns a new instance of Transfer.



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# File 'lib/dicoms/transfer.rb', line 26

def initialize(options = {})
  @output = options[:output]
end

Class Method Details

.min_max_limits(dicom) ⇒ Object 



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# File 'lib/dicoms/transfer.rb', line 82

def self.min_max_limits(dicom)
  num_bits = dicom_bit_depth(dicom)
  signed = dicom_signed?(dicom)
  pixel_value_range(num_bits, signed)
end

.strategy(strategy, options = {}) ⇒ Object 



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# File 'lib/dicoms/transfer.rb', line 41

def self.strategy(strategy, options = {})
  if strategy.is_a?(Array) && options.empty?
    strategy, options = strategy
  end
  return nil if strategy.nil?
  case strategy.to_sym
  when :fixed
    strategy_class = FixedTransfer
  when :window
    strategy_class = WindowTransfer
  when :first
    strategy_class = FirstTransfer
  when :global
    strategy_class = GlobalTransfer
  when :sample
    strategy_class = SampleTransfer
  when :identity
    strategy_class = IdentityTransfer
  else
    raise "INVALID: #{strategy.inspect}"
  end
  strategy_class.new options
end

Instance Method Details

#image(dicom, min, max) ⇒ Object

Remapped DICOM pixel values as an Image



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# File 'lib/dicoms/transfer.rb', line 31

def image(dicom, min, max)
  assign_dicom_pixels dicom, pixels(dicom, min, max)
  dicom.image
end

#min_max_limits(dicom) ⇒ Object

absolute output limits of the range (raw, not rescaled)



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# File 'lib/dicoms/transfer.rb', line 66

def min_max_limits(dicom)
  case @output
  when :byte
    [0, 255]
  when :unsigned
    min, max = Transfer.min_max_limits(dicom)
    if min < 0
      min = 0
      max -= min
    end
    [min, max]
  else
    Transfer.min_max_limits(dicom)
  end
end

#pixels(dicom, min, max) ⇒ Object

Remapped DICOM pixel values as an NArray



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# File 'lib/dicoms/transfer.rb', line 37

def pixels(dicom, min, max)
  processed_data(dicom, min, max)
end