After Effects
Importing Photoshop and
Illustrator Files
Importing a File from Photoshop or Illustrator into After Effects
Select File -> Import-> File or Multiple Files. A file dialog will pop up and you will select the file(s) that you want to import. Depending on what you want to import, select the appropriate option in the Import As popup.
The file that you want to import may be a single image with one layer or a file with multiple layers (sometimes a file appears to be a single image when it actually has a background layer with transparent layers). If there are multiple layers, then do the following:
1. make sure that this file with
layers is saved as a *.psd in Photoshop or *.ai in Illustrator.
2. decide if you want to import only one layer from the file, merge all the layers down to a single image on import, or import all of the layers as separate footage items. If you choose the latter, After Effects will automatically create a comp that includes all of the layers in the correct stacking order and position them as they were inside Photoshop. The layer names are used by After Effects, so try to name your layers in Photoshop in a way that you can easily recognize later.
If you want to import only one layer from the file or merge all layers
down to a single image on import:
a. In the file dialog (File > Import > File or Multiple Files), set Import As popup to Footage and click Import.
b. A second dialog appears and you can choose Merged Layers or an individual layer in the file.
If you want to import all the layers:
c. In the file dialog (File > Import > File or Multiple Files), set Import As popup to Composition and click Import.
For more details, look at page 376 of Creating Motion Graphics or go to Help > Adobe After Effects Help > Contents> Preparing and Importing Footage and select either Importing Adobe Photoshop Files or Importing Illustrator, PDF and EPS.