Adobe After Effects - Manual (Page 133)

Note:
Import a single still image or a still-image sequence
You can import still image files as individual footage items, or you can import a series of still image files as a still-image sequence, which is a
single footage item in which each still image is used as a single frame.
To import multiple image files as a single still-image sequence, the files must be in the same folder and use the same numeric or alphabetic
filename pattern (such as Seq1, Seq2, Seq3).
When you import a file that appears to After Effects to be one file in a still-image sequence, After Effects by default imports all other files in the
same folder that appear to be in the same sequence. Similarly, when you select multiple files that appear to be in a sequence, After Effects by
default imports them as a sequence. You can see what After Effects is about to import by looking at the bottom of the Import dialog box. You can
also import images and sequences by dragging files and folders into the Project panel.
To prevent After Effects from importing unwanted files when you want to import only a single file, or to prevent After Effects from interpreting
multiple files as a sequence, deselect the Sequence option in the Import dialog box. After Effects remembers this setting and thereafter uses it
as the default.
You can import multiple sequences from the same folder simultaneously by selecting files from different sequences and selecting Multiple
Sequences at the bottom of the Import dialog box.
When importing a sequence of still images, you can use the Force Alphabetical Order option in the Import dialog box to import a sequence with
gaps in its numbering (for example, Seq1, Seq2, Seq3, Seq5). If you import a sequence with gaps in its numbering without selecting this option,
After Effects warns you of missing frames and replaces them with placeholders.
After Effects uses settings of the first image in the sequence to determine how to interpret the images in the sequence.
If the image files in a sequence are of a layered file type—such as Adobe Photoshop or Adobe Illustrator documents—then you can choose to
import the sequence as a standard footage item, or as a composition in which each layer in each file is imported as a separate sequence and
appears as a separate layer in the Timeline panel.
When you render a composition that contains a numbered sequence, the output module uses the start frame number as the first frame
number. For example, if you start to render on frame 25, the name of the file is 00025.
A sequence of still-image files (left) becomes one image sequence when imported into After Effects (right).
Import a still-image sequence as a single footage item
1. Choose File > Import > File.
2. Select any file in the sequence. To import a subset of files in a sequence, select the first file, hold down Shift, and then select the last file to
import.
3. Choose Footage from the Import As menu.
4. Click Open (Windows) or Import (Mac OS).
5. In the [filename] dialog box, choose one of the following from the Choose Layer menu:
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