Importing images from Photoshop to AE and them being a different size on stage

[Roy_Hudd]

Hello,

I've created a jpeg which is 1920x1080px, but when I've imported it to the same sized composition in After Effects, it appears to be the wrong size on screen. Even the ratios are wrong, so I can't just grab the corner and scale up.
Can anyone please explain why this is happening?

Cheers!

[Roy_Hudd]

Ah, I think I've solved it myself; I've set the pixels to square in the comp. settings.
Secondary question: what does this mean for the output? Is there much difference in how it appears?

[davidarbor]

Yup, pixel aspect ratio is often the culprit here.

For output it depends what it means, but without getting into too much detail, non-square pixel aspect ratios are a relic of old formats, standard definition resolution (some older HD formats too), and tapes. These days, if you're only outputting for the web you 100% want square pixels. If you're going anywhere else it's still highly likely you want square pixels (especially if you're working in HD), but it's all about what format you're delivering and to where. 

If you want to learn a little more here's some info in Premiere's documentation: https://helpx.adobe.com/premiere-pro/using/aspect-ratios.html#Pixelaspectratio

[Roy_Hudd]

Thanks David - that's most helpful!

[davidarbor]

You're welcome! Glad to hear it was helpful.