android: tap image button to view high resolution image

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http://stackoverflow.com – I am a new android developer and I am trying to create an android app for android in which menu items will be displayed along with description cost and image. I have implemented List activity to display the items in a list. I made an image Button which will show the image in a thumbnail. I want to be able to view a high resolution image of the thumbnail when I tap on the image button. I have implemented an onClickListener to listen to the tap event but I do not knw the methods that will make the image zoom out on tap. I have followed the following link http://developer.android.com/training/ (HowTos)