This application sets new
pixel-index bounds for an NDF
, either trimming it to remove unwanted pixels, or
padding it with bad pixels
to achieve the required shape. The number of dimensions may
also be altered. The NDF is accessed in update mode and modified in situ, preserving
existing pixel values which lie within the new bounds.
LIKE = NDF (Read)
This parameter may be used to specify an NDF which is
to be used as a shape template. If such a template is supplied, then its bounds
will be used to determine the new shape required for the NDF specified via
the NDF parameter. By default no template will be used and the new shape will
be determined by means of a section specification applied to the NDF being
modified (see the “Examples”).
NDF = NDF (Read and Write)
The NDF whose
bounds are to be modified. In normal use, an NDF section
will be specified
for this parameter (see the “Examples”) and the routine will use the bounds
of this section to determine the new bounds required for the base NDF from
which the section is drawn. The base NDF is then accessed in update mode and
its bounds are modified in situ to make them equal to the bounds of the section
specified. If a section is not specified, then the NDF’s shape will only be
modified if a shape template is supplied via the LIKE parameter.
setbound datafile(1:512,1:512) Sets the pixel-index bounds of the NDF called
datafile to be (1:512, 1:512), either by trimming off unwanted pixels or by
padding out with bad pixels, as necessary.
setbound alpha(:7,56:) Modifies
the NDF called alpha so that its first dimension has an upper bound of 7 and
its second dimension has a lower bound of 56. The lower bound of the first
dimension and the upper bound of the second dimension remain unchanged.
Sets new bounds for the NDF called kg74b. The bounds of the first dimension are left
unchanged, but those of the second dimension are changed so that this dimension has
an extent of 100.0 centred on 5500.0, using the physical units in which this
second dimension is calibrated.
setbound newspec like=oldspec Changes
the bounds of the NDF newspec so that they are equal to the bounds of the NDF
setbound xflux(:2048) like=xflux Extracts the section
extending from the lower bound of the one-dimensional NDF called xflux up to pixel
2048, and then modifies the bounds of this section to be equal to the original
bounds of xflux, replacing xflux with this new NDF. This leaves the final shape
unchanged, but sets all pixels from 2049 onwards to be equal to the bad-pixel
setbound whole(5:10,5:10) like=whole(0:15,0:15) Extracts the section
(5:10, 5:10) from the base NDF called whole and then sets its bounds to be
equal to those of the section whole(0:15, 0:15), replacing whole with this new
NDF. The effect is to select a 6-pixel-square region from the original NDF
and then to pad it with a 5-pixel-wide border of bad pixels.
routine modifies the NDF in situ and will not release unused file space if the
size of the NDF is reduced. If recovery of unused file space is required, then
the related application NDFCOPY should be used. This will copy the selected
region of an NDF to a new data structure from which any unused space will be