sigmas=?
Parameters: IN = NDF (Read) The name of the input NDF (the .sdf extension is not required).
OUT = FILENAME (Write) The name of the GIF file to be generated (a .gif name extension is added
if it is omitted). If OUT is omitted, the value of the IN parameter is used. Any existing file with the
same name will be overwritten.
The following parameters are actually parameters of the ADAM task NDF2TIFF. Their values on the
NDF2GIF command line are just passed through to NDF2TIFF, which may prompt for other required
values. The output parameters SCAHIGH and SCALOW will be found in NDF2TIFF’s parameter
file.
HIGH = _DOUBLE (Read) Only required if SCALE is "Scale". The array value that
scales to 255 in the TIFF file. All larger array values are set to 255 when HIGH is greater
than LOW, otherwise all array values less than HIGH are set to 255. The dynamic default
is the maximum data value. There is an efficiency gain when both LOW and HIGH are
given on the command line, because the extreme values need not be computed. The
highest data value is suggested in prompts. LOW = _DOUBLE (Read) Only required
if SCALE is "Scale". The array value that scales to 0 in the TIFF file. All smaller array
values are also set to 0 when LOW is less than HIGH, otherwise all array values greater
than LOW are set to 0. The dynamic default is the minimum data value. There is an
efficiency gain when both LOW and HIGH are given on the command line, because the
extreme values need not be computed. The lowest data value is suggested in prompts.
MSG_FILTER = LITERAL (Read) The output message filtering level, QUIET, NORMAL or
VERBOSE. If set to verbose, the scaling limits used will be displayed. [NORMAL] NUMBIN
= _INTEGER (Read) Only used if SCALE is "Percentiles". The number of histogram
bins used to compute percentiles for scaling. (Percentiles mode) [2048] PERCENTILES(
2 ) = _REAL (Read) Only required if SCALE is "Percentiles". The percentiles that
define the scaling limits. For example, [25,75] would scale between the quartile values.
SCALE = LITERAL (Read) The type of scaling to be applied to the array. The
options, which may be abbreviated to an unambiguous string and are case-insensitive, are
described below: "Range" — The image is scaled between the minimum and maximum
data values. (This is the default.) "Faint" — The image is scaled from the mean minus
one standard deviation to the mean plus seven standard deviations. "Percentiles" —
The image is scaled between the values corresponding to two percentiles. "Scale" —
You define the upper and lower limits between which the image is to be scaled. The
application suggests the maximum and the minimum values minimum values when
prompting. "Sigmas" — The image is scaled between two standard-deviation limits.
["Range"] SIGMAS( 2 ) = _REAL (Read) Only required if SCALE is "Sigmas". The
standard-deviation bounds that define the scaling limits. To obtain values either side of
the mean both a negative and a positive value are required. Thus [-2,3] would scale
between the mean minus two and the mean plus three standard deviations. [3,-2] would
give the negative of that.
Results Parameters SCAHIGH = _DOUBLE (Write) The array value scaled to the maximum colour
index for display. SCALOW = _DOUBLE (Write) The array value scaled to the minimum colour
index for display. Examples: ndf2gif old new This converts the NDF called old (in file
old.sdf) into a GIF file new.gif. ndf2gif horse scale=pe This converts the NDF called
horse (in file horse.sdf) into a GIF file horse.gif using percentile scaling. The user will be
prompted for the percentiles to use. Notes: The following points should be remembered:
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This initial version of the script generates only 256 grey levels and does not use the image colour
lookup table so absolute data values may be lost.
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The NETPBM utilities tifftopnm and ppmtogif must be available on your PATH. Related
Applications
Copyright © 2015 Science and Technology Research Council
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