Module: RFits::Compressible

Included in:
Image
Defined in:
lib/rfits/rfits.rb

Overview

A set of routines for setting and retrieving compression characterstics.

Constant Summary collapse

COMPRESSION_TYPE_MAP = 
{
  IO::Proxy::RICE_1 => :rice,
  IO::Proxy::GZIP_1 => :gzip,
  IO::Proxy::PLIO_1 => :plio,
  IO::Proxy::HCOMPRESS_1 => :hcompress
}
COMPRESSION_DIM_KEY = 
'ZNAXIS'
COMPRESSION_TYPE_KEY = 
'ZCOMPTYPE'
COMPRESSION_TILE_KEY_ROOT = 
'ZTILE'
COMPRESSION_VAR_KEY_ROOT = 
'ZNAME'
COMPRESSION_VAR_VAL_ROOT = 
'ZVAL'
COMPRESSION_NOISE_BIT_NAME_VALUE = 
'NOISEBIT'
COMPRESSION_SCALE_NAME_VALUE = 
'SCALE'
COMPRESSION_SMOOTH_NAME_VALUE = 
'SMOOTH'

Instance Method Summary collapse

Instance Method Details

#activate_compression ⇒ Object

Activate compression on the image. “options” is a hash with the following keys:

:compression_type

the type of compression (:rice, :gzip, :plio, :hcompress). Required.

:tile_dim

the size of the tiles used in compression. Optional.

:noise_bits

applicable for floating point images only. Optional.

:hcomp_scale

scale factor for use in hcompress compression. Optional.

:hcomp_smooth

smoothing factor for use in hcompress compression. Optional.



856
857
858
859
860
861
862
 
# File 'lib/rfits/rfits.rb', line 856

def activate_compression
  self.compression_type = self.compression_options[:compression_type] if self.compression_options[:compression_type]
  self.tile_dim = self.compression_options[:tile_dim] if self.compression_options[:tile_dim]
  self.noise_bits = self.compression_options[:noise_bits] if self.compression_options[:noise_bits]
  self.hcomp_scale = self.compression_options[:hcomp_scale] if self.compression_options[:hcomp_scale]
  self.hcomp_smooth = self.compression_options[:hcomp_smooth] if self.compression_options[:hcomp_smooth]
end

#compression_type ⇒ Object

Retrieve the compression type of the image. Possible values: :rice, :gzip, :plio, :hcompress



870
871
872
873
874
875
876
877
878
879
880
881
882
883
 
# File 'lib/rfits/rfits.rb', line 870

def compression_type
  reset_position()
  
  ctype = case self.header['ZCMPTYPE']
    when 'GZIP_1'       then IO::Proxy::GZIP_1
    when 'RICE_1'       then IO::Proxy::RICE_1
    when 'HCOMPRESS_1'  then IO::Proxy::HCOMPRESS_1
    when 'PLIO_1'       then IO::Proxy::PLIO_1
    else
      raise "Unknown compression type #{self.header[COMPRESSION_TYPE_KEY]}."
  end
  
  COMPRESSION_TYPE_MAP[ctype]
end

#compression_type=(ctype) ⇒ Object

Set the compression type of the image. Possible values: :rice, :gzip, :plio, :hcompress

image.compression_type = :gzip



887
888
889
890
 
# File 'lib/rfits/rfits.rb', line 887

def compression_type=(ctype)
  ctype ? IO::Proxy.fits_set_compression_type(self.file.io, COMPRESSION_TYPE_MAP.invert[ctype.to_sym] || ctype) :
    IO::Proxy.fits_set_compression_type(self.file.io, nil)
end

#deactivate_compression ⇒ Object

Turn off compression for the image.



865
866
867
 
# File 'lib/rfits/rfits.rb', line 865

def deactivate_compression
  self.compression_type = 0
end

#hcomp_scale ⇒ Object

Get the hcompress scale if the image is compressed using hcompress.



926
927
928
929
930
931
932
933
 
# File 'lib/rfits/rfits.rb', line 926

def hcomp_scale
  reset_position()

  zname_name, zname_value, zname_comment = self.header.find { |name, value, comment|
    name.match(/^#{COMPRESSION_VAR_KEY_ROOT}/) and value == COMPRESSION_SCALE_NAME_VALUE
  }
  zname_name ? self.header["#{COMPRESSION_VAR_VAL_ROOT}#{zname_name.match(/^#{COMPRESSION_VAR_KEY_ROOT}(\d+)$/)[1]}"] : nil
end

#hcomp_scale=(scale) ⇒ Object

Set the hcompress scale if the image is compressed using hcompress.



936
937
938
 
# File 'lib/rfits/rfits.rb', line 936

def hcomp_scale=(scale)
  IO::Proxy.fits_set_hcomp_scale(self.file.io, scale.to_i)
end

#hcomp_smooth ⇒ Object

Get the hcompress smoothing factor if the image is compressed using hcompress.



941
942
943
944
945
946
947
948
 
# File 'lib/rfits/rfits.rb', line 941

def hcomp_smooth
  reset_position()
  
  zname_name, zname_value, zname_comment = self.header.find { |name, value, comment|
    name.match(/^#{COMPRESSION_VAR_KEY_ROOT}/) and value == COMPRESSION_SMOOTH_NAME_VALUE
  }
  zname_name ? self.header["#{COMPRESSION_VAR_VAL_ROOT}#{zname_name.match(/^#{COMPRESSION_VAR_KEY_ROOT}(\d+)$/)[1]}"] : nil
end

#hcomp_smooth=(smooth) ⇒ Object

Set the hcompress smoothing factor if the image is compressed using hcompress.



951
952
953
 
# File 'lib/rfits/rfits.rb', line 951

def hcomp_smooth=(smooth)
  IO::Proxy.fits_set_hcomp_smooth(self.file.io, smooth.to_i)
end

#noise_bits ⇒ Object

Get the noise bits for the compressed image.



911
912
913
914
915
916
917
918
 
# File 'lib/rfits/rfits.rb', line 911

def noise_bits
  reset_position()
  
  zname_name, zname_value, zname_comment = self.header.find { |name, value, comment|
    name.match(/^#{COMPRESSION_VAR_KEY_ROOT}/) and value == COMPRESSION_NOISE_BIT_NAME_VALUE
  }
  zname_name ? self.header["#{COMPRESSION_VAR_VAL_ROOT}#{zname_name.match(/^#{COMPRESSION_VAR_KEY_ROOT}(\d+)$/)[1]}"] : nil
end

#noise_bits=(bits) ⇒ Object

Set the noise bits for the compressed image.



921
922
923
 
# File 'lib/rfits/rfits.rb', line 921

def noise_bits=(bits)
  IO::Proxy.fits_set_noise_bits(self.file.io, bits.to_i)
end

#tile_dim ⇒ Object

Get the tile dimensions for the compressed image.



893
894
895
896
897
898
899
900
901
902
 
# File 'lib/rfits/rfits.rb', line 893

def tile_dim
  reset_position()
  
  tile_dims = []
  (1..self.header[COMPRESSION_DIM_KEY]).each do |i|
    tile_dims << self.header["#{COMPRESSION_TILE_KEY_ROOT}#{i}"]
  end
  
  tile_dims
end

#tile_dim=(tilesizes) ⇒ Object

Set the tile dimensions for the compressed image.

image.tile_dim = [5, 5]



906
907
908
 
# File 'lib/rfits/rfits.rb', line 906

def tile_dim=(tilesizes)
  IO::Proxy.fits_set_tile_dim(self.file.io, tilesizes.size, tilesizes)
end