Coyote Graphics Routines

Date: Fri Mar 27 12:14:20 2015

single page | use frames     summary     class     fields     routine details     file attributes


top cgBlendImage


cgBlendImage, foreGroundImage, backGroundImage [, ALPHA=float], WINDOW=WINDOW [, _REF_EXTRA=_REF_EXTRA]

This alpha blends two 24-bit images and displays them with the cgImage command.

The program requires the Coyote Library to be installed on your machine.


foreGroundImage in required type=truecolor

A 24-bit foreground image with the same dimensions as the background image.

backGroundImage in required type=truecolor

A 24-bit background image with the same dimensions as the foreground image.


ALPHA in optional type=float default=0.5

A number between 0 and 1 that indicates the percentage of the foreground image to alpha-blend into the background image. For example, ALPHA=0.2 will give a weigth of 20% to the foreground image pixels and 80% to the background image pixels. window: in, optional, type=intarr A one-, two-, or three-element array giving the window index numbers for the foreground, background, and display windows, repectively. If one-element, the foreground image is retrieved from that window and displayed in the current window. If two elements, the foreground and background images are obtained from the first two elements, respectively, and a new third display window is opened. This is the same for three elements, except the third element is used to specify the display window.

_REF_EXTRA in optional

Any keyword appropriate for the cgImage command is also accepted by keyword inheritance.

Author information



David W. Fanning 1645 Sheely Drive Fort Collins, CO 80526 USA Phone: 970-221-0438 E-mail: Coyote's Guide to IDL Programming:


Copyright (c) 2009-2012, Fanning Software Consulting, Inc.


Change History:

Written by: David W. Fanning, 26 May 2009. Added the WINDOW keyword. 16 February 2012. DWF.

File attributes

Modification date: Fri Mar 27 11:07:39 2015
Lines: 159
Docformat: rst rst