pmPeaks.h

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/** @file  pmPeaks.h
 *
 * The process of finding, measuring, and classifying astronomical sources on
 * images is one of the critical tasks of the IPP or any astronomical software
 * system. This file will define structures and functions related to the task
 * of source detection and measurement. The elements defined in this section
 * are generally low-level components which can be connected together to
 * construct a complete object measurement suite.
 *
 *  @author GLG, MHPCC
 *
 *  @version $Revision: 1.3 $ $Name: rel12 $
 *  @date $Date: 2006/06/03 01:02:08 $
 *
 *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
 *
 */

# ifndef PM_PEAKS_H
# define PM_PEAKS_H

/** pmPeakType
 *
 *  A peak pixel may have several features which may be determined when the
 *  peak is found or measured. These are specified by the pmPeakType enum.
 *  PM_PEAK_LONE represents a single pixel which is higher than its 8 immediate
 *  neighbors.  The PM_PEAK_EDGE represents a peak pixel which touching the image
 *  edge. The PM_PEAK_FLAT represents a peak pixel which has more than a specific
 *  number of neighbors at the same value, within some tolarence:
 *
 */
typedef enum {
    PM_PEAK_LONE,                       ///< Isolated peak.
    PM_PEAK_EDGE,                       ///< Peak on edge.
    PM_PEAK_FLAT,                       ///< Peak has equal-value neighbors.
    PM_PEAK_UNDEF                       ///< Undefined.
} pmPeakType;


/** pmPeak data structure
 *
 *  A source has the capacity for several types of measurements. The
 *  simplest measurement of a source is the location and flux of the peak pixel
 *  associated with the source:
 *
 */
typedef struct
{
    const int id;   ///< Unique ID for object
    int x;                              ///< X-coordinate of peak pixel.
    int y;                              ///< Y-coordinate of peak pixel.
    float counts;                       ///< Value of peak pixel (above sky?).
    pmPeakType type;                   ///< Description of peak.
}
pmPeak;


/** pmPeakAlloc()
 *
 *  @return pmPeak*    newly allocated pmPeak with all internal pointers set to NULL
 */
pmPeak *pmPeakAlloc(
    int x,    ///< Row-coordinate in image space
    int y,    ///< Col-coordinate in image space
    float counts,   ///< The value of the peak pixel
    pmPeakType type   ///< The type of peak pixel
);

bool pmIsPeak(const psPtr ptr);

/** pmFindVectorPeaks()
 *
 * Find all local peaks in the given vector above the given threshold. A peak
 * is defined as any element with a value greater than its two neighbors and with
 * a value above the threshold. Two types of special cases must be addressed.
 * Equal value elements: If an element has the same value as the following
 * element, it is not considered a peak. If an element has the same value as the
 * preceding element (but not the following), then it is considered a peak. Note
 * that this rule (arbitrarily) identifies flat regions by their trailing edge.
 * Edge cases: At start of the vector, the element must be higher than its
 * neighbor. At the end of the vector, the element must be higher or equal to its
 * neighbor. These two rules again places the peak associated with a flat region
 * which touches the image edge at the image edge. The result of this function is
 * a vector containing the coordinates (element number) of the detected peaks
 * (type psU32).
 *
 */
psVector *pmFindVectorPeaks(
    const psVector *vector,  ///< The input vector (float)
    float threshold   ///< Threshold above which to find a peak
);


/** pmFindImagePeaks()
 *
 * Find all local peaks in the given image above the given threshold. This
 * function should find all row peaks using pmFindVectorPeaks, then test each row
 * peak and exclude peaks which are not local peaks. A peak is a local peak if it
 * has a higher value than all 8 neighbors. If the peak has the same value as its
 * +y neighbor or +x neighbor, it is NOT a local peak. If any other neighbors
 * have an equal value, the peak is considered a valid peak. Note two points:
 * first, the +x neighbor condition is already enforced by pmFindVectorPeaks.
 * Second, these rules have the effect of making flat-topped regions have single
 * peaks at the (+x,+y) corner. When selecting the peaks, their type must also be
 * set. The result of this function is an array of pmPeak entries.
 *
 */
psArray *pmFindImagePeaks(
    const psImage *image,  ///< The input image where peaks will be found (float)
    float threshold   ///< Threshold above which to find a peak
);


/** pmCullPeaks()
 *
 * Eliminate peaks from the psList that have a peak value above the given
 * maximum, or fall outside the valid region.
 *
 */
psList *pmCullPeaks(
    psList *peaks,   ///< The psList of peaks to be culled
    float maxValue,   ///< Cull peaks above this value
    const psRegion valid                ///< Cull peaks otside this psRegion
);


/** pmPeaksSubset()
 *
 * Create a new peaks array, removing certain types of peaks from the input
 * array of peaks based on the given criteria. Peaks should be eliminated if they
 * have a peak value above the given maximum value limit or if the fall outside
 * the valid region.  The result of the function is a new array with a reduced
 * number of peaks.
 *
 */
psArray *pmPeaksSubset(
    psArray *peaks,                     ///< Add comment.
    float maxvalue,                     ///< Add comment.
    const psRegion valid                ///< Add comment.
);

int pmPeaksCompareAscend (const void **a, const void **b);
int pmPeaksCompareDescend (const void **a, const void **b);

# endif /* PM_PEAKS_H */

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