## NAME

overlap -- Overlaps two images in X or Y, by a certain amount of columns or lines.

## USAGE

`overlap input1 input2 output dx dy`

## DESCRIPTION

This task creates a composite 2-D output image from two input 2-D
images.
The composite is the result of overlapping the two input images
by a certain amount of lines or columns. The amount is specified
by task parameters `dx` and `dy`. If `dx>0` and, `dy=0`, the input
images are overlapped columnwise: last `dx` columns of `input1`
are overlapped with first `dx` columns of `input2`.
The input images must have the same number
of lines.
If `dx=0` and `dy>0`, the images are overlapped linewise, and
they must have the same number of columns.

The overlapped region is built as a weighted average of the relevant
regions in the input images, and the weight function is specified
by task parameter `weight`. It can be either a linear or a cos
tapering function.

## PARAMETERS

- input[file name]
- First input 2-d image section.

- input[file name]
- Second input 2-d image section.

- output [file name]
- Output image. Always type real, regardless of input image type.

- dx = [integer, min=0]
- Amount of overlap in X direction (pixels).

- dy = [integer, min=0]
- Amount of overlap in Y direction (pixels).

- (weight = "cos") [string, Allowed values: cos | linear]
- Type of weighting function used in overlapped region.

## EXAMPLES

1. Overlap in X images `image1` and `image2` by 100 pixels, using
linear weighting:

pl> overlap image1.hhh image2.hhh output.hhh dx=100 dy=0 weight="linear"

## BUGS

## SEE ALSO