blendimage.pro
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;+
; NAME:
; BLENDIMAGE
;
; PURPOSE:
;
; This alpha blends two 24-bit images and displays them with the TVIMAGE command.
;
; AUTHOR:
;
; FANNING SOFTWARE CONSULTING
; David Fanning, Ph.D.
; 1645 Sheely Drive
; Fort Collins, CO 80526 USA
; Phone: 970-221-0438
; E-mail: david@idlcoyote.com
; Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
;
; CATEGORY:
;
; Graphics
;
; CALLING SEQUENCE:
;
; BlendImage, foregroundImage, backgroundImage
;
; INPUTS:
;
; foregroundImage: A 24-bit foreground image with the same dimensions as the background image.
;
; backgroundImage: A 24-bit background image with the same dimensions as the foreground image.
;
; KEYWORD PARAMETERS:
;
; ALPHA: 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. By default, 0.5.
;
; Note: Any keywords appropriate to the TVIMAGE command are also accepted.
;
; MODIFICATION HISTORY:
;
; Written by: David W. Fanning, 26 May 2009.
;-
;
;******************************************************************************************;
; Copyright (c) 2009, by Fanning Software Consulting, Inc. ;
; All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
PRO BlendImage, foreGroundImage, backGroundImage, ALPHA=alpha, _EXTRA=extra
; Error handling.
Catch, theError
IF theError NE 0 THEN BEGIN
void = Error_Message()
RETURN
ENDIF
; Need a foreground and a background image.
IF N_Params() NE 2 THEN Message, 'Usage: "BlendedImage, foreGroundImage, backGroundImage"'
; Condition alpha blending value.
IF N_Elements(alpha) EQ 0 THEN alpha = 0.5
alpha = 0.0 > alpha < 1.0
; Do input image dimensions match?
IF Total( Size(foregroundImage, /DIMENSIONS) EQ Size(backgroundImage, /DIMENSIONS) ) NE 3 $
THEN Message, 'Dimensions and/or size of input images do not match.'
; Output the blended image.
cgImage, (foreGroundImage * alpha) + (1 - alpha) * backGroundImage, _EXTRA=extra
END