How to make smaller backup images of Rpi SD card?

I always keep backups of my raspberry pi's, but the only way that I've ever seen to do this is using the dd command on OSX. It works fine, I keep a few backups this way, and it's very easy, but it becomes troublesome when every backup is the full size of the SD card, which is usually 16GB. I'm pretty sure I've seen people upload their rPi images to websites before with much smaller file sizes. Is there a better way to do this? Any way to backup a pi without a huge file size, or maybe compress it afterward?

 TinyURL was created here!
http://tinyurl.com/RpiSDcard


Backup, Restore, Customize and Clone your Raspberry Pi SD Cards (tutorial)

Check out sysmatt's script, i think it's exactly what you need.
https://reddit.com/r/raspberry_pi/comments/2ct1gn/backup_restore_customize_and_clone_your_raspberry/

http://sysmatt.blogspot.com/2014/08/backup-restore-customize-and-clone-your.html


A few more examples (you can scroll past the first bit):
http://lnx.cx/docs/vdg/html/ch02s02.html

Most involve using
'kpartx' / 'gparted' at some point, if you google that with 'raspberry pi' -
you find lots of examples, videos etc.

You can something like this to make the file sparse saving space

.cp -v --sparse=always pi.img ./tmp

A simple solution would probably be to compress the images. The empty space on the SD-card-image is probably represented by just 0's which would be really easy to compress. If I'm not mistaken, OSX comes with gzip2 pre-installed (a command line utility) altough I'm not sure about that.

There are a few ways to do this, here's a straightforward-ish one:
http://softwarebakery.com/shrinking-images-on-linux

Softwarebakery
Shrinking images on LinuxWhen creating images from existing ISOs you often need to allocate a number of MB for the image to at least fit the files that are in the ISO. Predicting the exact size of the image is hard, even for a program. In this case you will create an image that is larger than actually needed: the image is much larger than the files on the image are combined.
This post will show how to shrink an existing image to a more optimal size. We will do this on Linux, since all required tools are available there: GParted, fdisk and truncate.
https://softwarebakery.com//shrinking-images-on-linux

Shrinking Raspberry Pi SD Card Images
http://www.aoakley.com/articles/2015-10-09-resizing-sd-images.php

Cloning a larger SD card to a smaller one (with a catch)
https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=13028