Re: free transform the image

try sthg like:

var g = app.activeDocument.allPageItems;
var gr = app.activeDocument.groups.add(g);
var bgr = gr.geometricBounds;
var hgr = bgr[2]-bgr[0];  
var pm= gr.parentPage.marginPreferences;
with(pm){
var t = top;
var b = bottom;    } 
gr.move([bgr[1],t]); 
var hn = gr.parentPage.bounds[2] - gr.parentPage.bounds[0] - t - b;
var s = hn / hgr ;
tM = app.transformationMatrices.add({horizontalScaleFactor:s,   verticalScaleFactor:s});             gr .transform(CoordinateSpaces.INNER_COORDINATES,   AnchorPoint.TOP_CENTER_ANCHOR, tM );