casacore::ImageFITSConverter Class Reference

Interconvert between Casacore Images and FITS files. More...

#include <ImageFITSConverter.h>

Static Public Member Functions
static Bool	FITSToImage (ImageInterface< Float > *&newImage, String &error, const String &imageName, const String &fitsName, uInt whichRep=0, Int whichHDU=0, uInt memoryInMB=64, Bool allowOverwrite=False, Bool zeroBlanks=False)
	Convert a FITS file to a Casacore image. More...
static Bool	ImageToFITS (String &error, ImageInterface< Float > &image, const String &fitsName, uInt memoryInMB=64, Bool preferVelocity=True, Bool opticalVelocity=True, Int BITPIX=-32, Float minPix=1.0, Float maxPix=-1.0, Bool allowOverwrite=False, Bool degenerateLast=False, Bool verbose=True, Bool stokesLast=False, Bool preferWavelength=False, Bool airWavelength=False, const String &origin=String(), Bool history=True)
	Convert a Casacore image to a FITS file. More...
static Bool	ImageHeaderToFITS (String &error, ImageFITSHeaderInfo &fhi, const ImageInterface< Float > &image, Bool preferVelocity=True, Bool opticalVelocity=True, Int BITPIX=-32, Float minPix=1.0, Float maxPix=-1.0, Bool degenerateLast=False, Bool verbose=True, Bool stokesLast=False, Bool preferWavelength=False, Bool airWavelength=False, Bool primHead=True, Bool allowAppend=True, const String &origin=String(), Bool history=True)
static IPosition	copyCursorShape (String &report, const IPosition &shape, uInt imagePixelSize, uInt fitsPixelSize, uInt memoryInMB)
	Helper function - used to calculate a cursor appropriate for the desired memory use. More...
static CoordinateSystem	getCoordinateSystem (Int &imageType, RecordInterface &headerRec, const Vector< String > &header, LogIO &os, uInt whichRep, IPosition &shape, Bool dropStokes)
	Recover CoordinateSystem from header. More...
static ImageInfo	getImageInfo (RecordInterface &header)
	Recover ImageInfo from header. More...
static Unit	getBrightnessUnit (RecordInterface &header, LogIO &os)
	Recover brightness unit from header. More...
static void	restoreHistory (LoggerHolder &logger, ConstFitsKeywordList &kw)
	Recover history from FITS file keyword list into logger. More...
static Bool	extractMiscInfo (RecordInterface &miscInfo, const RecordInterface &header)
	Parse header record and set MiscInfo. More...
static void	readBeamsTable (ImageInfo &info, const String &filename, const DataType type)
	Read the BEAMS table if present and add the restoring beams to info. More...

Static Public Attributes
static const String	CASAMBM

Static Private Member Functions
static Bool	ImageToFITSOut (String &error, LogIO &os, const ImageInterface< Float > &image, FitsOutput *output, uInt memoryInMB=64, Bool preferVelocity=True, Bool opticalVelocity=True, Int BITPIX=-32, Float minPix=1.0, Float maxPix=-1.0, Bool degenerateLast=False, Bool verbose=True, Bool stokesLast=False, Bool preferWavelength=False, Bool airWavelength=False, Bool primHead=True, Bool allowAppend=False, const String &origin=String(), Bool history=True)
	Put a CASA image to an opened FITS image Parameters as in "ImageToFITS". More...
static Bool	QualImgToFITSOut (String &error, LogIO &os, ImageInterface< Float > &image, FitsOutput *outfile, uInt memoryInMB, Bool preferVelocity, Bool opticalVelocity, Int BITPIX, Float minPix, Float maxPix, Bool degenerateLast, Bool verbose, Bool stokesLast, Bool preferWavelength, Bool airWavelength, const String &origin, Bool history)
	Put a CASA image with quality coordinate to an opened FITS file Parameters as in "ImageToFITS". More...
static Bool	removeFile (String &error, const File &outFile, const String &outName, Bool allowOverwrite)
	If existing, remove the file, symlink, or directory given by outFile. More...
static Bool	openFitsOutput (String &error, FitsOutput *(&openFitsOutput), const String &fitsName, const Bool &allowOverwrite)
	Create an open FITS file with the name given. More...
static void	_writeBeamsTable (FitsOutput *const &outfile, const ImageInfo &info)

Detailed Description

Interconvert between Casacore Images and FITS files.

Intended use:

Public interface

Review Status

Date Reviewed:

yyyy/mm/dd

Prerequisite

• PagedImage
• PrimaryArray (and FITS concepts in general).

Synopsis

This class is a helper class that is used to interconvert between Casacore images and FITS files. This adds no functionality over the general abilities available in the underlying FITS classes, however it is a useful higher-level packaging.

There are two fundamental member functions in this class. FITSToImage which turns a FITS file into a Casacore image, and ImageToFITS which does the opposite.

We can read images from any HDU inside the FITS file (although this isn't well tested). Images with a quality axis (i.e. contain data and error values) are stored in the primary HDU (data) and an extension HDU (error). Other images are always written to the primary HDU.

Pixels in the FITS file which are blanked are masked out (the mask is set to False) in the output image. On conversion to FITS, masked values are blanked. The mask which is read is the current default mask.

Example

A FITS to image conversion may be accomplished as follows:

PagedImage<Float> *image = 0;
String fitsName = "exists.fits";
String imageName = "new.image";
String error;
Bool ok = ImageFITSConverter::FITSToImage(image, error, imageName, fitsName);
if (!image)... error..\.

A couple of things to note:

• If ok is False, the conversion failed and error will be set.
• The pointer "image" is set if the conversion succeeds. If it is zero the conversion failed and error will contain an error message.
• The caller is responsible for deleting the pointer image when the conversion is successful.

Similarly, an image to FITS conversion may be accomplished as follows:

String imageName = argv[1];
PagedImage<Float> image =...; // An existing image from somewhere
String fitsName = "new.fits";
String error;
Bool ok = ImageFITSConverter::ImageToFITS(error, image, fitsName);

A couple of similar remarks can be made about this example:

• If ok is False, the conversion failed and error will be set.

Motivation

FITS files are the fundamental transport format for images in Astronomy.

To Do

• It might be useful to have functions that convert between FITS and general lattices.
• Add support for PagedImage<Complex>
• Convert multiple images at once?
• Allow writing FITS files to an image extension in an existing FITS file.

Definition at line 170 of file ImageFITSConverter.h.

Member Function Documentation

_writeBeamsTable()

static void casacore::ImageFITSConverter::_writeBeamsTable ( FitsOutput *const &  outfile, const ImageInfo &  info  )

staticprivate

copyCursorShape()

static IPosition casacore::ImageFITSConverter::copyCursorShape ( String &  report, const IPosition &  shape, uInt  imagePixelSize, uInt  fitsPixelSize, uInt  memoryInMB  )

static

Helper function - used to calculate a cursor appropriate for the desired memory use.

It's not intended that application programmers call this, but you may if it's useful to you.

extractMiscInfo()

static Bool casacore::ImageFITSConverter::extractMiscInfo ( RecordInterface &  miscInfo, const RecordInterface &  header  )

static

Parse header record and set MiscInfo.

FITSToImage()

static Bool casacore::ImageFITSConverter::FITSToImage ( ImageInterface< Float > *&  newImage, String &  error, const String &  imageName, const String &  fitsName, uInt  whichRep = 0, Int  whichHDU = 0, uInt  memoryInMB = 64, Bool  allowOverwrite = False, Bool  zeroBlanks = False  )

static

Convert a FITS file to a Casacore image.

• newImage will be zero if the conversion fail. If the conversion succeeds, the caller is responsible for deleting this pointer.
• error will be set if the conversion fails.
• If imageName is empty, a TempImage will be created, otherwise a PagedImage on disk.
• fitsName must already exist (and have an image at the indicated HDU).
• whichRep Zero-relative coordinate representation (Starting with wcs FITS multiple coordinate representations can be stored in a FITS file)
• whichHDU Zero-relative hdu. The default is correct for a primary array, set it for an image extension. A value of -1 makes the code look for the first readable HDU.
• memoryInMB. Setting this to zero will result in row-by-row copying, otherwise it will attempt to with as large a chunk-size as possible, while fitting in the desired memory.
• allowOverwrite If True, allow imageName to be overwritten if it already exists.
• zeroBlanks If True, allow any blanked pixels are set to zero rather than NaN

getBrightnessUnit()

static Unit casacore::ImageFITSConverter::getBrightnessUnit ( RecordInterface &  header, LogIO &  os  )

static

Recover brightness unit from header.

Used keywords are removed from header.

getCoordinateSystem()

static CoordinateSystem casacore::ImageFITSConverter::getCoordinateSystem ( Int &  imageType, RecordInterface &  headerRec, const Vector< String > &  header, LogIO &  os, uInt  whichRep, IPosition &  shape, Bool  dropStokes  )

static

Recover CoordinateSystem from header.

Used keywords are removed from header and the unused ones returned in a Record for ease of use. Degenerate axes may be added to shape if needed.

getImageInfo()

static ImageInfo casacore::ImageFITSConverter::getImageInfo ( RecordInterface &  header )

static

Recover ImageInfo from header.

Used keywords are removed from header

ImageHeaderToFITS()

static Bool casacore::ImageFITSConverter::ImageHeaderToFITS ( String &  error, ImageFITSHeaderInfo &  fhi, const ImageInterface< Float > &  image, Bool  preferVelocity = True, Bool  opticalVelocity = True, Int  BITPIX = -32, Float  minPix = 1.0, Float  maxPix = -1.0, Bool  degenerateLast = False, Bool  verbose = True, Bool  stokesLast = False, Bool  preferWavelength = False, Bool  airWavelength = False, Bool  primHead = True, Bool  allowAppend = True, const String &  origin = String(), Bool  history = True  )

static

ImageToFITS()

static Bool casacore::ImageFITSConverter::ImageToFITS ( String &  error, ImageInterface< Float > &  image, const String &  fitsName, uInt  memoryInMB = 64, Bool  preferVelocity = True, Bool  opticalVelocity = True, Int  BITPIX = -32, Float  minPix = 1.0, Float  maxPix = -1.0, Bool  allowOverwrite = False, Bool  degenerateLast = False, Bool  verbose = True, Bool  stokesLast = False, Bool  preferWavelength = False, Bool  airWavelength = False, const String &  origin = String(), Bool  history = True  )

static

Convert a Casacore image to a FITS file.

• return True if the conversion succeeds, False otherwise.
• error will be set if the conversion fails.
• image The image to convert.
• fitsName If the name is "-" (the minus character), then write to stdout Always writes to the primary array.
• memoryInMB. Setting this to zero will result in row-by-row copying, otherwise it will attempt to with as large a chunk-size as possible, while fitting in the desired memory.
• preferVelocityWrite a velocity primary spectral axis if possible.
• opticalVelocityIf writing a velocity, use the optical definition (otherwise use radio).
• BITPIX, minPix, maxPix BITPIX can presently be set to -32 or 16 only. When BITPIX is 16 it will write BSCALE and BZERO into the FITS file. If minPix is greater than maxPix the minimum and maximum pixel values will be determined from the array, otherwise the supplied values will be used and pixels outside that range will be truncated to the minimum and maximum pixel values (note that this truncation does not occur for BITPIX=-32).
• allowOverwrite If True, allow fitsName to be overwritten if it already exists.
• degenerateLast If True, axes of length 1 will be written last to the header.
• preferWavelength If True, write a wavelength primary axis.
• airWavelength If True and preferWavelength is True write an air wavelength primary axis.
• origin gives the origin, i.e., the name of the package. If empty, it defaults to "casacore-"getVersion().

ImageToFITSOut()

static Bool casacore::ImageFITSConverter::ImageToFITSOut ( String &  error, LogIO &  os, const ImageInterface< Float > &  image, FitsOutput *  output, uInt  memoryInMB = 64, Bool  preferVelocity = True, Bool  opticalVelocity = True, Int  BITPIX = -32, Float  minPix = 1.0, Float  maxPix = -1.0, Bool  degenerateLast = False, Bool  verbose = True, Bool  stokesLast = False, Bool  preferWavelength = False, Bool  airWavelength = False, Bool  primHead = True, Bool  allowAppend = False, const String &  origin = String(), Bool  history = True  )

staticprivate

Put a CASA image to an opened FITS image Parameters as in "ImageToFITS".

In addition:

• output The FITS output to write to.
• primHead Write to a primary HDU.
• allowAppend Allow to append extension HDU's.

openFitsOutput()

static Bool casacore::ImageFITSConverter::openFitsOutput ( String &  error, FitsOutput *&  openFitsOutput, const String &  fitsName, const Bool &  allowOverwrite  )

staticprivate

Create an open FITS file with the name given.

QualImgToFITSOut()

static Bool casacore::ImageFITSConverter::QualImgToFITSOut ( String &  error, LogIO &  os, ImageInterface< Float > &  image, FitsOutput *  outfile, uInt  memoryInMB, Bool  preferVelocity, Bool  opticalVelocity, Int  BITPIX, Float  minPix, Float  maxPix, Bool  degenerateLast, Bool  verbose, Bool  stokesLast, Bool  preferWavelength, Bool  airWavelength, const String &  origin, Bool  history  )

staticprivate

Put a CASA image with quality coordinate to an opened FITS file Parameters as in "ImageToFITS".

In addition:

• output The FITS output to write to.

readBeamsTable()

static void casacore::ImageFITSConverter::readBeamsTable ( ImageInfo &  info, const String &  filename, const DataType  type  )

static

Read the BEAMS table if present and add the restoring beams to info.

removeFile()

static Bool casacore::ImageFITSConverter::removeFile ( String &  error, const File &  outFile, const String &  outName, Bool  allowOverwrite  )

staticprivate

If existing, remove the file, symlink, or directory given by outFile.

It is only removed if allowOverwrite=True. An exception (using argument outName) is thrown if the file could not be removed.

restoreHistory()

static void casacore::ImageFITSConverter::restoreHistory ( LoggerHolder &  logger, ConstFitsKeywordList &  kw  )

static

Recover history from FITS file keyword list into logger.

Member Data Documentation

CASAMBM

const String casacore::ImageFITSConverter::CASAMBM

static

Definition at line 173 of file ImageFITSConverter.h.

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The documentation for this class was generated from the following file:

• images/Images/ImageFITSConverter.h