SETBOUND - Sets new bounds for an NDF

Description:

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.

Usage:

setbound ndf

Parameters:

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.

Examples:

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.

setbound ndf=kg74b(,5500.0$\sim$100.0)

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 called oldspec.

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 value.

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.

Notes:

This 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 eliminated.

Related Applications

KAPPA: NDFCOPY, SETORIGIN; FIGARO: ISUBSET.