// Image Preload
	var backImage = new Array();

	backImage[0] = "http://webench.national.com/filters/images/LP_FreqResp.gif";
	backImage[1] = "http://webench.national.com/filters/images/HP_FreqResp.gif";
	backImage[2] = "http://webench.national.com/filters/images/BP_FreqResp.gif";
	backImage[3] = "http://webench.national.com/filters/images/BS_FreqResp.gif";
	
    // Change Image per Filter Type
    function ChangeImage() {

    	var filterType;
       	for (i = 0; i < document.dynaInputForm.filterType.length; i++) {
       		if (document.dynaInputForm.filterType[i].checked) {
           		filterType = document.dynaInputForm.filterType[i].value;
      		}
    	}

       	if (filterType == 'Lowpass') {
	   		document.filterTypeImage.src = backImage[0];
    	} else if (filterType == 'Highpass') {
	   		document.filterTypeImage.src = backImage[1];
    	} else if (filterType == 'Bandpass') {
	   		document.filterTypeImage.src = backImage[2];
    	} else if (filterType == 'Bandstop') {
	    	document.filterTypeImage.src = backImage[3];
     	}

   	} // ChangeImage()