Module: Magro::IO

Defined in:
lib/magro/io.rb,
ext/magro/magro.c,
ext/magro/magro.c

Overview

IO module provides functions for input and output of image file.

Class Method Summary collapse

Class Method Details

.imread(filename) ⇒ Numo::UInt8

Loads an image from file.

Parameters:

  • filename (String) —

    File path or URL of image file to be loaded. Currently, the following file formats are support: Portbale Network Graphics (*.png) and JPEG files (*.jpeg, *.jpg, *jpe).

Returns:

  • (Numo::UInt8) —

    (shape: [height, width, n_channels]) Loaded image.

Raises:

  • (ArgumentError) —

    This error is raised when filename is not String.

  • (IOError) —

    This error is raised when failed to read image file.

  • (NoMemoryError) —

    If memory allocation of image data fails, this error is raised.



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# File 'lib/magro/io.rb', line 19

def imread(filename) # rubocop:disable Metrics/AbcSize
  raise ArgumentError, 'Expect class of filename to be String.' unless filename.is_a?(String)

  unless url?(filename)
    return case filename.downcase
           when /\.(jpeg|jpg|jpe)$/
             read_jpg(filename)
           when /\.png$/
             read_png(filename)
           end
  end

  uri = URI.parse(filename)
  ext = File.extname(uri.path).downcase
  raise IOError, 'Failed to detect file extension from given URL.' unless /\.(jpeg|jpg|jpe|png)$/.match?(ext)

  uri.open do |file|
    temp = Tempfile.new(['magro_', ext])
    temp.binmode
    temp.write(file.read)
    temp.rewind
    imread(temp.path)
  end
end

.imsave(filename, image, quality: nil) ⇒ Boolean

Saves an image to file.

Parameters:

  • filename (String) —

    Path to image file to be saved. Currently, the following file formats are support: Portbale Network Graphics (*.png) and JPEG files (*.jpeg, *.jpg, *jpe).

  • image (Numo::UInt8) —

    (shape: [height, width, n_channels]) Image data to be saved.

  • quality (Integer) (defaults to: nil) —

    Quality parameter of jpeg image that takes a value between 0 to 100.

Returns:

  • (Boolean) —

    true if file save is successful.

Raises:

  • (ArgumentError) —

    If filename is not String or image is not Numo::NArray, this error is raised.

  • (IOError) —

    This error is raised when failed to write image file.

  • (NoMemoryError) —

    If memory allocation of image data fails, this error is raised.



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# File 'lib/magro/io.rb', line 54

def imsave(filename, image, quality: nil)
  raise ArgumentError, 'Expect class of filename to be String.' unless filename.is_a?(String)
  raise ArgumentError, 'Expect class of image to be Numo::NArray.' unless image.is_a?(Numo::NArray)

  if /\.(jpeg|jpg|jpe)$/.match?(filename.downcase)
    unless quality.nil?
      raise ArgumentError, 'Expect class of quality to be Numeric.' unless quality.is_a?(Numeric)
      raise ArgumentError, 'Range of quality value between 0 to 100.' unless quality.between?(0, 100)
    end
    return save_jpg(filename, image, quality)
  end

  return save_png(filename, image) if /\.png$/.match?(filename.downcase)

  false
end