After Effects tutorial day 3

We seem to have covered masses today; from animation in Photoshop to basic masking tools in After Effects. I'm very familiar with Photoshop's frame animation interface already, but I'd never understood the timeline panel so it was great to finally get to grips with that!

We covered exporting image sequences in Photoshop both as JPEGs and PNGs to preserve transparency. We were then shown how to import these into After Effects correctly. Image sequences themselves are exactly that — still images with no frame rate assigned to them. As a result After Effects will usually default to playing them back at 30fps, regardless of your composition settings. To rectify this you need to change the image sequence's "interpret footage" settings.

After we'd successfully imported our animations we were introduced to masks, which work very much the same way as they do in Photoshop. By drawing and creating vector shapes you're effectively "masking off" the area within that shape. You can set a mask to be additive or subtractive — this basically means whether it shows or hides whatever is within the confines of that shape.

I used a simple eliptical mask filled with black to create a shadow for my jumping frog:

I added a slight feathering to the mask to give the shadow a softer edge. I used two or three keyframes to mark the shadow's size when the frog was at the highest and lowest points — to make it smaller and larger, respectively.

As another example we were shown how to use a subtractive mask to remove the Mona Lisa image from its frame, replacing it with a "keep calm and carry on" image. It's also possible to animate masks — they have properties that can be keyframed, just like everything else.

I drew a simple subtractive mask to remove the Mona Lisa from her frame, and then keyframed the mask path from right to left to give it a "wipe" effect. The text was another, slightly feathered "additive" mask that started very small (hiding all the text from sight) keyframed to gradually expand, revealing the text.

We were then shown something much cooler:

By nesting the frame and the keep calm image inside their own composition (effectively acting as flattening them into one layer) we were able to apply a circular additive mask (revealing only that within the circle) to act as a spotlight. By keyframing the mask path we were able to make it appear as a spotlight searching around — when the "light" hit the centre, we could simply keyframe the mask expansion property to scale the mask up, revealing the entire image.

I'm really happy with the outcome of this lesson. Masks are an incredibly dynamic way of working and, with a little creativity, it greatly negates the need for using Photoshop to make quick adjustments.