I guess your question is how to keep the original dimensions on the image and be able to pan it around with your finger. Titanium does not have this feature natively. However there is a work around using a ScrollView instead.
var suivi = Titanium.UI.createImageView({
top:"10%",
width:"100%",
height:"90%"
});
var scrollView = Ti.UI.createScrollView({
contentWidth:'auto',
contentHeight:'auto',
top:0,
showVerticalScrollIndicator:true,
showHorizontalScrollIndicator:true,
minZoomScale:0,
maxZoomScale:10,
zoomScale:0
});
scrollView.add(suivi);
And add the scrollView to you window.