function FindImage( oDocument, strImage ) {
	var oImage = null;

    if( oDocument != null ) {
	    if( oDocument.images != null ) {
	        oImage = oDocument.images[strImage];
        }
        if( oImage == null ) {
	        if( oDocument.layers != null ) {
  	        	var iLayer = 0;

              	while( (iLayer < oDocument.layers.length) && (oImage == null) ) {
	            	oImage = FindImage( oDocument.layers[iLayer++].document, strImage );
              	}
            }
        }
	}

    return oImage;
}

function ChangeImage( strImage, strSource ) {
	var oImage = FindImage( document, strImage );

    if( oImage != null ) {
	    oImage.src = strSource;
    }
}