How to resize the image before uploading to coudinary?

This is my first time to post a question here. I was building a meteor app with image uploading functions. I found a cloudinary package for meteor http://ift.tt/1Bwnoci and it works pretty well. The only and the biggest problem I have is the resizing of image. By default this package will upload the original image taken from phone, which is often 3 or 4 MB and whose size is around 2000x4000, but I only want image to a few KBs. And because of this problem, it takes so much storage and bandwidth for the app. What should I do to fix this problem ? Thank you very much.