OPLOTIMAGE Name
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.
Optional Inputs
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
Outputs
NONE
Procedure
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
See Also
PLOTIMAGE, BYTSCL
EXTERNAL SUBROUTINES:
SUBCELL, DEFSUBCELL, TVIMAGE
Modification History
Written, CM, 1997
Removed BYTE requirement, added ON_ERROR, CM 19 Apr 2000
Added copyright notice, CM 25 Mar 2001