IMAGE_CONT Procedure

Reference Guide > I–L Routines > IMAGE_CONT Procedure

Standard Library procedure that overlays a contour plot onto an image display of the same array.

Usage

IMAGE_CONT, array

Input Parameters

array—The two-dimensional array to display.

Keywords

Aspect—Set to 1 to change the image’s aspect ratio. It assumes square pixels. If Aspect is not set, the aspect ratio is retained.

Interp—Set to 1 to interpolate the image with the bilinear method, when and if the image is resampled. Otherwise, the nearest neighbor method is used.

Window_Scale—Set to 1 to scale the window size to the image size. Otherwise, the image size is scaled to the window size. Window_Scale is ignored when outputting to devices with scalable pixels (e.g., PostScript devices).

Discussion

If the device you are using has scalable pixels, then the image is written over the plot window.

Example

This example uses IMAGE_CONT to display the image and overlaid contour plot depicting different elevations of the surface defined by:

f(x,y) = xsin(y) + ycos(x) - 10sin(xy/4)

where:

(x,y) ∈ {R2 | x, y ∈ [-10, 10]}

The results are shown in Figure 10-1: Image Contour Plot on page 610.

.RUN

; Define the function.

FUNCTION f, x, y

   RETURN, x * SIN(y) + y * COS(x) - 10 * SIN(0.25 * x * y)

END

; Create vector of x-coordinates.

x = FINDGEN(101)/5 - 10

; Create vector of y-coordinates.

y = x

; Create an array to hold the function values.

z = FLTARR(101, 101)

; Evaluate the function at the given x- and y-coordinates and

; place the result in z.

FOR i=0L, 100 DO FOR j=0L, 100 DO z(i, j) = f(x(i), y(j))

; Display image and contour plot.

IMAGE_CONT, z

Figure 10-1: Image Contour Plot