Aspect ratio

When i import image sequences which are 1024x576 it squashes them back to 4:3, even thou they are 16:9, and also in the script it outputs at the end it says the aspect ratio is 0.75.
Once i’ve changed that in the text file it all lines up, but it’s still a pain.
also when i bring in HD 1920x1440 it doesn’t do that, it brings that in 16:9.
Any ideas?