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 $Id: oplotimage.pro,v 1.2 2001/03/25 18:10:44 craigm Exp $