كيف اتحكم في حجم الصورة في داخل الـ GridView

السلام عليكم ورحمة الله وبركاته

عندي هذا الكود يعمل 100%

ولكني اريد التحكم في حجم الصورة داخل داخل الـ GridView

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" 
    android:background="@drawable/back_mqdmah"

    >

   <GridView 

       android:id="@+id/gridView"
       android:layout_width="fill_parent"
    android:layout_height="290dp"
    android:numColumns="auto_fit"
    android:verticalSpacing="10dp"
    android:horizontalSpacing="1dp"
    android:columnWidth="100dp"
    android:stretchMode="columnWidth"
    android:gravity="center"
       android:layout_marginTop="160dp" 
       >

   </GridView>

</LinearLayout>

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;

public class Mypage_mqdmah extends Activity{

	Integer[] imagenesID = {
			R.drawable.icn1_mqdmh,R.drawable.icn2_mqdmh,R.drawable.icn3_mqdmh,R.drawable.icn4_mqdmh,
			R.drawable.icn5_mqdmh,R.drawable.icn6_mqdmh
		};

	    /** Called when the activity is first created. */
	    @Override
	    public void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);

	        requestWindowFeature(Window.FEATURE_NO_TITLE);
	        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
	        WindowManager.LayoutParams.FLAG_FULLSCREEN);
	        setContentView(R.layout.page_mqdmah);

	        GridView gridView = (GridView) findViewById(R.id.gridView);
	        gridView.setAdapter(new ImageAdapter(this));
	    }

	    public class ImageAdapter extends BaseAdapter{

	    	private Context contexto;

	    	public ImageAdapter (Context c){
	    		contexto =c;	
	    	}

			@Override
			public int getCount() {
				// TODO Auto-generated method stub
				return imagenesID.length;
			}

			@Override
			public Object getItem(int position) {
				// TODO Auto-generated method stub
				return position;
			}

			@Override
			public long getItemId(int position) {
				// TODO Auto-generated method stub
				return position;
			}

			@Override
			public View getView(int position, View convertView, ViewGroup parent) {
				// TODO Auto-generated method stub
				ImageView imageView;

				if(convertView == null){
					imageView = new ImageView(contexto);
					imageView.setLayoutParams(new GridView.LayoutParams(100, 100));
					imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);

				}else{
					imageView = (ImageView) convertView;
			}
				imageView.setImageResource(imagenesID[position]);
			return imageView;

	    }
	}}