Resize the image to save memory useage

Hi folks.

I am developing an mobile app which needs to take a picture and upload that picture to server. To save the memory, I need to resize (or should I call it compress) that picture.

I found a similar project ImageResizer which can resize the picture but I did not know if that resize also cut the memory use. If it does which step or function (Bitmap.CreateScaledBitmap() or Bitmap.Compress()) shrink the memory usage? How could I get the size of the new image represented by Kbs?

Thank you.