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OPLOTIMAGE

OPLOTIMAGE

## Author

Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
craigm@lheamail.gsfc.nasa.gov

## Purpose

Overlays an image on an existing plot.

## Calling Sequence

OPLOTIMAGE, img

## Description

OPLOTIMAGE overlays an image on an already-existing set of plot
axes. It should not matter what plot elements have already be
displayed, but at least one command is needed to set up the plot
axes.
Only the IMGXRANGE and IMGYRANGE keywords, specifying the extent
of the image, can be given in a call to OPLOTIMAGE.
See PLOTIMAGE for more detailed information.

## Inputs

IMG - A byte array to be displayed. An image declared as
ARRAY(M,N) will be M pixels in the x-direction and N pixels
in the y-direction. The image is resampled via
interpolation to fill the desired display region.

NONE

## Input Keyword Parameters

IMGXRANGE, IMGYRANGE - Each is a two component vector that
describes the X and Y position of the first
and last pixels.
Default: the size of the image in pixels

NONE

## Example

This example first constructs an image whose values are found by
z(x,y) = cos(x) * sin(y)
and x and y are in the range [-2,2] and [4,8], respectively.
The image is then plotted in the range [-10, 10] in both x and
y directions.

x = findgen(20)/5. - 2.
y = findgen(20)/5. + 4.
zz = cos(x) # sin(y)
imgxrange = [min(x), max(x)]
imgyrange = [min(y), max(y)]
xr=[-10.,10]
yr=[-10.,10]
plotimage, bytscl(zz), imgxrange=imgxrange, imgyrange=imgyrange
Now for the overlay. A new image is created in the ranges between
-10 and 0:
z(x,y) = x y
x = findgen(20)/2 - 10.
y = findgen(20)/2 - 10.
imgxrange = [min(x), max(x)]
imgyrange = [min(y), max(y)]
zz = x # y
oplotimage, bytscl(zz), imgxrange=imgxrange, imgyrange=imgyrange

PLOTIMAGE, BYTSCL
EXTERNAL SUBROUTINES:
SUBCELL, DEFSUBCELL, TVIMAGE

## Modification History

Written, CM, 1997
Removed BYTE requirement, added ON_ERROR, CM 19 Apr 2000