dsubsamp(1)

PROGRAM
dsubsamp - Subsamples 1-D vector(s).

SYNTAX

dsubsamp

-i  input image

-o  resulting output image

[-s]
    Subsample skip value (0 = no skipping)

[-x]
    Point to begin subsampling

[-d]
    data processing direction (0 = down vectors, 1 = across bands)

[-V]
    Gives the version for dsubsamp

[-U]
    Gives the usage for dsubsamp

[-P]
    Prompts for command line options

[-A [file1]]
    Creates the answer file called dsubsamp.ans or file1

[-a [file1]]
    Uses dsubsamp.ans or file1 as the answer file

DESCRIPTION
dsubsamp subsamples 1-dimensional vector(s) from the input data. The position where the first sample is taken can be specified by the start parameter (-x). For example, x = 0 will start subsampling with the first point in each vector. The number of points skipped between each sample is specified by the skip parameter (-s). A skip value of 0 will cause no skipping to occur.

Input and Output Files
    The input file must be of data storage type VFF_TYP_FLOAT or VFF_TYP_COMPLEX, be of dimension = 0, and have implicit location type. The output file will contain the same number of vectors and be of the same data storage type as is in the input file. The vector dimension of the output file will be the determined by the skip value.

Skip Value
    The skip parameter (-s) is an integer which describes how many points should be skipped between samples. For example, a skip value of 2 would result in the following points being sampled from the input sequence: 0, 3, 6, 9 ... .

First Sample Point
    The first subsample point (-x) specifies a constant offset into the input data vector(s) where the first sample point is taken.

Data Processing Direction
    Data can be processed with either band or vector orientation. If vector processing is chosen, the 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 changed so that each band is processed as a signal (instead of each vector being a signal) by setting the process direction to band (d = 1).

REQUIRED ARGUMENTS

-i  type: infile
    desc: input image

-o  type: outfile
    desc: resulting output image

OPTIONAL ARGUMENTS

-s  type: integer
    desc: Subsample skip value (0 = no skipping)
    default: 0
    bounds: value >= 0

-x  type: integer
    desc: Point to begin subsampling
    default: 0
    bounds: value >= 0

-d  type: boolean
    desc: data processing direction (0 = down vectors, 1 = across bands)
    default: true

EXAMPLES
dsubsamp -i in_file -o out_file -x 3 -s 2

Out_file will contain the sampled set of vectors from in_file The first point in out_file will be point 3 (fourth point) from in_file, and each subsequent point will be 2 points away from the previous point. For example, in this out_file sequence, points 0,1,2 ... will contain the values indexed by 3, 6, 9, ... in in_file.

SEE ALSO
intro(1), verror(3), vgparms(3), vutils(3), ldsubsamp(3)

RESTRICTIONS
Dsubsamp works only on VFF_TYP_COMPLEX and VFF_TYP_FLOAT.

Dsubsamp does not work on explicit location data and will return an error when such a data file is encountered.

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