astro.fits

Class MFitsStarFind

java.lang.Object

util.PropertyContainer

util.PropertyResources

astro.fits.MFitsStarFind

All Implemented Interfaces:

MSifting, Cloneable, Initializable, PropertySupplying, ResourceSupplying

public class MFitsStarFind
extends PropertyResources
implements MSifting, Initializable

Author:

wooz

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MFitsStarFind.FileMatch
static class	MFitsStarFind.Reduce Allows off-line reduction of acquire, guiding, and focus frames.

Nested classes/interfaces inherited from class util.PropertyResources

PropertyResources.Load, PropertyResources.URLResource

Field Summary

Fields

Modifier and Type	Field and Description
private static boolean	DEFFASTGAUSS
private static int	DEFSKYFRAME
private static double	DEFSKYTHRESHOLD
static String	KEY_DETECTIONLIMIT Stars have a probability higher than this value.
static String	KEY_ELONGATIONMAX The maximum elongation for a valid star detection, 0=round.
static String	KEY_ELONGATIONWIDTH The steepness of the elongation drop.
static String	KEY_FASTGAUSS
static String	KEY_GLOBALWIDTH The sharpness peak width for a valid star detection.
static String	KEY_SHARPLOWLIMIT Overexposed star may even fall below this.
static String	KEY_SHARPLOWVALUE Then we give this for the sharpness indicator.
static String	KEY_SHARPPEAKS The sharpness peak for a valid star detection.
static String	KEY_SHARPWIDTHS The sharpness peak width for a valid star detection.
static String	KEY_SKYFRAME
static String	KEY_SKYTHRESHOLD
static String	KEY_STRIPDISTANCE Read-out stripes have this maximum column offset.
static String	KEY_STRIPESMAX Read-out stripes have this maximum stroke.
static String	KEY_SURESTRIPES Strokes below this are immediately identified as stripes.

Fields inherited from class util.PropertyResources

KEY_NOINITONCREATE, POSTFIX_ALPHABET, POSTFIX_BYTES, POSTFIX_DIR, POSTFIX_EXT, POSTFIX_FILE, POSTFIX_LIST, POSTFIX_MODTIME, POSTFIX_URL

Fields inherited from class util.PropertyContainer

KEY_LISTSEPARATOR, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR

Fields inherited from interface util.ResourceSupplying

KEY_URLRESOURCES, KEY_URLUSECONFIG, KEY_URLUSECURRENT, KEY_URLUSEHOME

Fields inherited from interface util.PropertySupplying

CONFIG, KEY_CLASS

Constructor Summary

Constructors

Constructor and Description
MFitsStarFind(Map<String,String> props)

Method Summary

Modifier and Type	Method and Description
float[]	gauss(MImageHDU hdu, double fwhm, double trunc) Prepares a reduced image for star detection by applying a truncated Gaussian filter to it.
List<StarDetection>	getDetectedStars(Rectangle readout, Dimension binning, MImageHDU reduced, float[] gauss, int datamin, int datamax, int searchbox, int thick, float[] xstripes, float[] ystripes) Detect stars in the images using the reduced (or raw) frame plus the gaussian-filtered one.If the detector is shutterless, consider also to look for horizontal or vertical stripes.
private List<StarDetection>	getStrip(List<StarDetection> principal, Point2D center) We scan a list of StarDetections and return all entries that are within a certain column, defined in center.
void	init()
private boolean	isStar(StarDetection star) We compare the stars sharpness with an allowed list of peaks and width.
MImageHDU	reduce(MImageHDU raw, double exptime, MImageHDU bias, MImageHDU dark, double darktime, MImageHDU flat) Prepares a raw image HDU by applying bias reduction, dark and flat-field correction.
List<StarDetection>	removeSpurious(List<StarDetection> raw) We compare each entry to a allowed range of sharpness and elongation.
protected List<StarDetection>	removeStripes(List<StarDetection> stars) For bright stars, stars brighter than 9th mag, read-out stripes can be seen in the image because of the shutterless operation.
static boolean	save(File write, ArrayLayout geom, float[] reduced) Convenience for saving 16-bit image hdu in fits files.
static boolean	save(File write, MImageHDU reduced) Convenience for saving image hdu in fits files.
float[]	xstripes(MImageHDU reduced, double fwhm, double trunc) Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the x-axis.
float[]	ystripes(MImageHDU reduced, double fwhm, double trunc) Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the y-axis.

Methods inherited from class util.PropertyResources

clone, createFrom, createFrom, createFrom, createInstance, getApplet, getAsResources, getLocate, getPropertiesToKey, getPropertiesToKey, getResource, getResourceAsStream, getResourceFromKey, getResources, hasLocalURLs, initProperties, keyCreate, keyCreate, reload, setApplet

Methods inherited from class util.PropertyContainer

augment, augment, augment, augment, augment, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, isNew, parseObject, parseObject, reload, removeProperty, requires, rescanned, setObject, setProperties, setProperty, stringProperties, toString

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface util.PropertySupplying

defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, parseObject, removeProperty, setObject, setProperty, stringProperties

Field Detail

KEY_SKYFRAME

public static final String KEY_SKYFRAME

See Also:

Constant Field Values

KEY_SKYTHRESHOLD

public static final String KEY_SKYTHRESHOLD

See Also:

Constant Field Values

KEY_FASTGAUSS

public static final String KEY_FASTGAUSS

See Also:

Constant Field Values

KEY_DETECTIONLIMIT

public static final String KEY_DETECTIONLIMIT

Stars have a probability higher than this value.

See Also:

Constant Field Values

KEY_SHARPPEAKS

public static final String KEY_SHARPPEAKS

The sharpness peak for a valid star detection.

See Also:

Constant Field Values

KEY_SHARPWIDTHS

public static final String KEY_SHARPWIDTHS

The sharpness peak width for a valid star detection.

See Also:

Constant Field Values

KEY_GLOBALWIDTH

public static final String KEY_GLOBALWIDTH

The sharpness peak width for a valid star detection.

See Also:

Constant Field Values

KEY_ELONGATIONMAX

public static final String KEY_ELONGATIONMAX

The maximum elongation for a valid star detection, 0=round.

See Also:

Constant Field Values

KEY_ELONGATIONWIDTH

public static final String KEY_ELONGATIONWIDTH

The steepness of the elongation drop.

See Also:

Constant Field Values

KEY_SHARPLOWLIMIT

public static final String KEY_SHARPLOWLIMIT

Overexposed star may even fall below this.

See Also:

Constant Field Values

KEY_SHARPLOWVALUE

public static final String KEY_SHARPLOWVALUE

Then we give this for the sharpness indicator.

See Also:

Constant Field Values

KEY_SURESTRIPES

public static final String KEY_SURESTRIPES

Strokes below this are immediately identified as stripes.

See Also:

Constant Field Values

KEY_STRIPESMAX

public static final String KEY_STRIPESMAX

Read-out stripes have this maximum stroke.

See Also:

Constant Field Values

KEY_STRIPDISTANCE

public static final String KEY_STRIPDISTANCE

Read-out stripes have this maximum column offset.

See Also:

Constant Field Values

DEFSKYFRAME

private static final int DEFSKYFRAME

See Also:

Constant Field Values

DEFSKYTHRESHOLD

private static final double DEFSKYTHRESHOLD

See Also:

Constant Field Values

DEFFASTGAUSS

private static final boolean DEFFASTGAUSS

See Also:

Constant Field Values

Constructor Detail

MFitsStarFind

public MFitsStarFind(Map<String,String> props)

Parameters:

props -

Method Detail

init

public void init()

Specified by:

init in interface Initializable

reduce

public MImageHDU reduce(MImageHDU raw,
                        double exptime,
                        MImageHDU bias,
                        MImageHDU dark,
                        double darktime,
                        MImageHDU flat)
                 throws BasicFitsException

Description copied from interface: MSifting

Prepares a raw image HDU by applying bias reduction, dark and flat-field correction. The dark must be normalized to the nominal exposure time of 1 and bias-subtracted. Any of the bias/dark/flat can be null and of any bit-depth.

Specified by:

reduce in interface MSifting

exptime - The exposure time in multiples of the dark nominal exposure time

Returns:

A 16-bit reduced ImageHDU

Throws:

BasicFitsException

gauss

public float[] gauss(MImageHDU hdu,
                     double fwhm,
                     double trunc)
              throws BasicFitsException

Description copied from interface: MSifting

Prepares a reduced image for star detection by applying a truncated Gaussian filter to it. This is similar to the DAO Starfinder algorithm.

Specified by:

gauss in interface MSifting

Returns:

A 16-bit gauss-filtered image as a float array

Throws:

BasicFitsException

xstripes

public float[] xstripes(MImageHDU reduced,
                        double fwhm,
                        double trunc)
                 throws BasicFitsException

Description copied from interface: MSifting

Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the x-axis.

Specified by:

xstripes in interface MSifting

Returns:

A 16-bit gauss-filtered image.

Throws:

BasicFitsException

ystripes

public float[] ystripes(MImageHDU reduced,
                        double fwhm,
                        double trunc)
                 throws BasicFitsException

Description copied from interface: MSifting

Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the y-axis.

Specified by:

ystripes in interface MSifting

Returns:

A 16-bit gauss-filtered image.

Throws:

BasicFitsException

getDetectedStars

public List<StarDetection> getDetectedStars(Rectangle readout,
                                            Dimension binning,
                                            MImageHDU reduced,
                                            float[] gauss,
                                            int datamin,
                                            int datamax,
                                            int searchbox,
                                            int thick,
                                            float[] xstripes,
                                            float[] ystripes)
                                     throws BasicFitsException

Description copied from interface: MSifting

Detect stars in the images using the reduced (or raw) frame plus the gaussian-filtered one.If the detector is shutterless, consider also to look for horizontal or vertical stripes.

Specified by:

getDetectedStars in interface MSifting

reduced - The reduced image, only for photometry.

gauss - The convolved image for star center using datamin and max

datamin - Minimum ADU value to spike star detection

datamax - Maximum value for a star, can be 65535

searchbox - Half-radius of the search box.

thick - No stars this close to the edges searched. Must be >= searchbox.

Returns:

A list of detected stars, with sharpness, elongation and streakiness.

Throws:

BasicFitsException

removeSpurious

public List<StarDetection> removeSpurious(List<StarDetection> raw)

We compare each entry to a allowed range of sharpness and elongation. From that, a star probablility is calculated and a star is considered a true detection, if this probablity is high enough.

Specified by:

removeSpurious in interface MSifting

Parameters:

raw - All detections (ADU above certain threshold in filtered image).

Returns:

The list of detections removed from the original list.

removeStripes

protected List<StarDetection> removeStripes(List<StarDetection> stars)

For bright stars, stars brighter than 9th mag, read-out stripes can be seen in the image because of the shutterless operation. We remove those here assuming the following: The star that produces the read-out stripes is always at the position with the highest y value. Stripes have only marginally different x. The stroke parameter of the raw star is then queried, if it is lower than KEY_STRIPESMAX, the image is considered a read-out stripe and removed from the list.

This method is only there for convenience, see ReadoutStripes.

isStar

private boolean isStar(StarDetection star)

We compare the stars sharpness with an allowed list of peaks and width. The closer this star's sharpness to the allowed peaks, the higher its probablity to be a true star. In a last step, its elongation is tested to be as round as possible. All together describe a probability value, if high enough we decide for a positive detection of a star.,

Parameters:

star -

Returns:

getStrip

private List<StarDetection> getStrip(List<StarDetection> principal,
                                     Point2D center)

We scan a list of StarDetections and return all entries that are within a certain column, defined in center.

save

public static boolean save(File write,
                           MImageHDU reduced)
                    throws IOException

Convenience for saving image hdu in fits files.

Throws:

IOException

save

public static boolean save(File write,
                           ArrayLayout geom,
                           float[] reduced)
                    throws IOException,
                           BasicFitsException

Convenience for saving 16-bit image hdu in fits files.

Throws:

BasicFitsException

IOException