I need to send to a printing company one of my photos to print out a 37 9/16" x 32 3/8" of my picture and make it a poster. I made my picture in After Effects- rendered out as a 1920x1080 PNG file- threw it in Photoshop and resized it to be 37 9/16" x 32 3/8". When I do this the photo is stretch long ways so I guess I'm failing to keep the proper ratio back in After Effects. This is my first time trying to print something this big. How do I tell After Effects to keep the right ratio so that when I size it up in Photoshop to be 37 9/16" x 32 3/8" it's not stretched wrong?
You're using the wrong tool. This is a job for Photoshop, not AE.
The poster is darned near square, but you made the image wide in AE. Why is that?
You said nothing about the DPI at which the poster will be printed. Let's say it's something low, like 150 DPI. The poster's longer dimension would be more than 5500 dots.... or pixels. So why did you limit yourself to 1920 pixels across.... and in AE, to boot?
I think I'd sit down and have a nice chat with the printer about what he/she expects you to deliver for optimum quality. I think it would be an eye-opener for you.