– Common Function Library Project

imageScale(selector, oldHeight, oldWidth, newParameter)

Last updated October 13, 2006


Greg Nettles

Version: 1 | Requires: CF5 | Library: UtilityLib

Returns a width or height of an image when scaled down to a specified height or width while maintaining the original aspect ratio.

Return Values:
Returns a number.


<cfset oldWidth = 660>
<cfset oldHeight = 495>
<!--- scale by height --->
<cfset newHeight = 90>
Scale by Height<br>
<cfset newWidth = imageScale('h',oldHeight,oldWidth,newHeight)>
Old Dimensions: #oldWidth# x #oldHeight#<br>
New Dimensions: <strong>#newWidth#</strong> x #newHeight#<br><br>

<!--- scale by width --->
<cfset newWidth = 120>
Scale by Width<br>
<cfset newHeight = imageScale('w',oldHeight,oldWidth,newWidth)>
Old Dimensions: #oldWidth# x #oldHeight#<br>
New Dimensions: #newWidth# x <strong>#newHeight#</strong><br>


Name Description Required
selector Dimension to scale. Either h (for height) or w (for width). Yes
oldHeight Old height. Yes
oldWidth Old width. Yes
newParameter New size. Yes

Full UDF Source:

 * Returns width or height of a scaled image.
 * @param selector      Dimension to scale. Either h (for height) or w (for width). (Required)
 * @param oldHeight      Old height. (Required)
 * @param oldWidth      Old width. (Required)
 * @param newParameter      New size. (Required)
 * @return Returns a number. 
 * @author Greg Nettles ( 
 * @version 1, October 18, 2006 
function imageScale(selector,oldHeight,oldWidth,newParameter) {
        var ratioA = oldHeight/oldWidth;
        var ratioB = oldWidth/oldHeight;
        if (selector is 'h') {
            return round(newParameter * (1/ratioA));
        } else if (selector is 'w') {
            return round(newParameter * (1/ratioB));


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