SPEXPAND

Name

spexpand

Purpose (one Line Only)

Sparse expansion of an array

Description

This routine expands an image by in integer factor in both dimensions.
The original pixels from the input image are carried over to the LLHC
of the nxn expanded area that maps back to the pixel. The other pixels
in the expanded image are set to 0. This effectively converts the image
into a 2-D shah (III) function.
This routine does a 2x2 expansion (could be generalized if needed).
The purpose of this routine is to support the reconstruction of
undersampled dithered images. (see XXX.pro)

Calling Sequence

result=spexpand(image)

Inputs

image - Input image to be expanded.

Optional Input Parameters

Keyword Input Parameters

ROOT2 - Flag, if set requests an expansion of the image by sqrt(2).
The geometry of this necessitates a 45 degree rotation of the
image. The default is a 2x2 expansion.

Outputs

return value is the expanded image

Keyword Output Parameters

Common Blocks

Side Effects

Restrictions

Procedure

Modification History

2016/09/06, Written by Marc W. Buie, Southwest Research Institute
2017/01/12, MWB, added ROOT2 keyword option