Twitter embedded image sizes/positioning

Hello all!

I really hope one of you have tackled this because my Google searches have been leaving me with nothing.

My goal for today was to try to create a graphic template that allowed me to post the same graphics both to Facebook and Twitter, but to have them post in the native image size. I've been listening/reading to a lot of Gary Vaynerchuk lately and I agree with him when he talks crap to these big fortune 500 companies who can't even create a graphic that is native to the platform. I.e. you post a picture and everything gets cut off. Obviously, you can click on an image and it will expand to the full size, but if you really want to catch people, it should at least transmit the main message BEFORE you click on it.

All that said, I've been doing 1000x1000 for facebook. It scales it down, but it posts the entire image in the timeline. Twitter will "expand" a photo if you click on it, but before you click it is at a 600x300 ratio. So 1000x500 works fine as well.

My "genius" idea this morning was to see how I could make my Facebook graphics (my primary focus) so that they'd look good when posted on twitter. I looked at one picture and it looked like Twitter had just focused on the center 50% of my 1000x1000 graphic. I figured, sweet, all I need to do is center the most important part of my text. But then I went and looked at another post and found that it centered on the top of the graphic. Now, both times, it centered on a main part of my text. My assumption now is that Twitter attempts to center the graphic over the text. Maybe I'm wrong? That actually makes things harder, because you'll never know if it chooses where you want.

In conclusion, I figured that I'd add that I use Hootsuite to post my graphics. So making things work through there is my ultimate goal. Hopefully someone who has worked with this will comment. Either way, I'll report back. I think that knowing how to post images so that they are getting the best bang for their buck is something that we all should know if we plan to succeed in this business.