How to resize(zoom in/out) an image?

You can use scale transform to change the size of the image. If scaling is above one , it will zoom the image.
 

public static Bitmap scaleImage(Bitmap src,float sx,float sy)
{
    Matrix matrix = new Matrix();
    matrix.postScale(sx, sy);
    src=Bitmap.createBitmap(src, 0, 0,   src.getWidth(), src.getHeight(), matrix, true);
    return src;
}

 
If you have byte array, you can convert that to Bitmap object and can call this method.
 
Here is how you can convert it to byte array.
 

Bitmap.createBitmap(image, w, h, android.graphics.Bitmap.Config.ARGB_8888);