Class RFits::ImageData
In: lib/rfits/rfits.rb
Parent: Object

Represents the actual pixels in a FITS file.

Methods

[]   []=   column   each   each_column   each_row   first   last   length   new   pixels   row   set_column   set_pixels   set_row  

Included Modules

Enumerable

Constants

BITPIX_IMG_MAP = { IO::Proxy::BYTE_IMG => IO::Proxy::TBYTE, IO::Proxy::SHORT_IMG => IO::Proxy::TSHORT, IO::Proxy::LONG_IMG => IO::Proxy::TLONG, IO::Proxy::LONGLONG_IMG => IO::Proxy::TLONGLONG, IO::Proxy::FLOAT_IMG => IO::Proxy::TFLOAT, IO::Proxy::DOUBLE_IMG => IO::Proxy::TDOUBLE, IO::Proxy::SBYTE_IMG => IO::Proxy::TSBYTE, IO::Proxy::USHORT_IMG => IO::Proxy::TUSHORT, IO::Proxy::ULONG_IMG => IO::Proxy::TULONG

Attributes

image  [R]  The image the data belongs to.

Public Class methods

new(image)

Create an ImageData object associated with the specified image.

Public Instance methods

[](*args)

An alias for ImageData#pixels, but automatically chooses the datatype for you based on the type of image (i.e. BITPIX).

[]=(*args)

An alias for ImageData#set_pixels, but automatically chooses the datatype for you based on the type of image (i.e. BITPIX).

column(i)

Retrieve the ith (where i is zero-based) column of the image array. Assumes a two-dimensional image.

each() {|self[i]| ...}

Iterate through each pixel in the array.

each_column() {|self.column(i, i)| ...}

Iterate through each column of pixels in the array. Assumes a two-dimensional image.

each_row() {|self.row(i, i)| ...}

Iterate through each row of pixels in the array. Assumes a two-dimensional image.

first()

The first pixel in the image array.

last()

The last pixel in the image array.

length()

The number of pixels in the image array.

pixels(datatype, *args)

Retrieve the value of a pixel, or a range of pixels. The value is coerced into an appropriate class according to the datatype provided. Can be used in a number of ways. The simplest plucks the nth pixel from the image array: 

 image.data.pixels(IO::Proxy::TSHORT, 0)  # first pixel in the image (remember zero-based indexing?)
 image.data.pixels(IO::Proxy::TSHORT, image.data[image.data.size - 1])  # last pixel in the image

You can also choose a range of contiguous pixels, in which case an array of values is returned: 

 image.data.pixels(IO::Proxy::TSHORT, 0..10)  # retrieve first 10 pixels

or pick the single pixel at a particular coordinate: 

 image.data.pixels(IO::Proxy::TSHORT, 4, 5)

or equivalently: 

 image.data.pixels(IO::Proxy::TSHORT, [4, 5])

In addition, you can give an (x,y) coordinate and a number of pixels, assuming the coordinates are zero-based: 

 image.data.pixels(IO::Proxy::TSHORT, [4, 5], 10)  # 10 pixels starting at the point [4, 5]

or get all the pixels between two points: 

 image.data.pixels(IO::Proxy::TSHORT, [4, 5], [6, 6]) # all the pixels between the points [4, 5] and [6, 6]
row(i)

Retrieve the ith (where i is zero-based) row of the image array. Assumes a two-dimensional image.

set_column(i, vals)

Set the ith column of a 2D image to the specified pixels.

set_pixels(datatype, *args)

Set the value of a pixel, or a range of pixels. The value is coerced into an appropriate class according to the datatype provided. Can be used in a number of ways. The simplest sets the nth pixel in the image array: 

 image.data.set_pixels(IO::Proxy::TSHORT, 0, 5)  # first pixel in the image is set to 5

You can also set a range of contiguous pixels: 

 image.data.set_pixels(IO::Proxy::TSHORT, 0..10, [5, 5, 3, 1, 0, 9, 5, 6, 7, 1])  # set first 10 pixels

or set the single pixel at a particular coordinate: 

 image.data.set_pixels(IO::Proxy::TSHORT, 4, 5, 10) # set pixel at [4, 5] to 10

or equivalently: 

 image.data.set_pixels(IO::Proxy::TSHORT, [4, 5], 10)

In addition, you can give an (x,y) coordinate and a list of pixels, assuming the coordinates are zero-based: 

 image.data.set_pixels(IO::Proxy::TSHORT, [4, 5], [1, 2, 3, 4])  # four pixels with values 1, 2, 3, 4 starting at [4, 5]

or set the pixels between two points: 

 image.data.set_pixels(IO::Proxy::TSHORT, [0, 0], [1, 1], [5, 6, 7, 8]) # set pixels to (5, 6, 7, 8) between [0, 0] and [1, 1]
set_row(i, vals)

Set the ith row of a 2D image to the specified pixels.

[Validate]