ldextract(3)

LIBRARY ROUTINE
ldextract - Extracts 1-D Subsignal(s)

LIBRARY CALL
#include "vinclude.h"
int
ldextract(image, start, end_flg, length, process_dir)
struct xvimage  *image;
int             start,       /* starting point for extracted signal */
                end_flg,     /* flag set to one if extracting to end of file */
                length,      /* if end_flg = 0, length of output sequence */
                process_dir; /* direction of processing 0=vect, 1= band */

INPUT

image
    (struct xvimage) Input/output image file structure.

start
    (int) Specifies the offset into the data set where the first point of the output sequence is.

end_flg
    (int) Flag set to one if extracting to end of file.

length
    (int) If end_flg = 0, specifies length of output sequence.

process_dir
    (int) Direction of processing 0=vect, 1= band.

OUTPUT

image
    (struct xvimage) Input/output image file structure.

MODIFICATIONS

12 Mar 1991 12:43 MST Jeremy Worley
    set image->startx to indicate start of subimage.

19 Feb 1992 08:58 MST Jeremy Worley
    explicitly declared function dunload_vector().

DESCRIPTION
ldextract extracts 1-dimensional subsignals from the input data file.

Ldextract will extract N subsignal vectors from an input file of N signal vectors. All vectors will be extracted starting from the same initial position (start), and all will be of the same length depending on end_flg and length pararmeters. Ldextract works only on VFF_TYP_FLOAT or VFF_TYP_COMPLEX data files.

start
    The start parameter specifies the offset into the data set where the first point of the output sequence is. The default value is 0 (the first point of the input series).

end_flg & length
    Two mutually exclusive options are available for specifying the length of the output sequence. The length is specified by the values of end_flg and length.

    If end_flg is TRUE, ldextract calculates the number of points to the right of the first point specified (start), and the output file is assigned this calculated length.

    If end_flg is FALSE, the length of the output sequence is specified by the length parameter. If the specified length value is greater than the input file length minus start, ldextract returns an error and exits.

process_dir
    Data can be processed with either band or vector orientation (process_dir parameter). Vector processing means that data stored in multiband format will be processed as a set of data sequences, where each sequence corresponds to a pixel location, and the points of each sequence are defined by the bands corresponding to that pixel location. The direction of processing can be set so that each band is processed as a signal (instead of each vector being a signal) by setting process_dir to 1.

SEE ALSO
dextract(1), intro(3), vipl(3), verror(3), vutils(3)

RESTRICTIONS
Ldextract works only on VFF_TYP_COMPLEX and VFF_TYP_FLOAT.

AUTHOR
Donna Koechner

COPYRIGHT
Copyright 1991, University of New Mexico. All rights reserved.