Using Layers & Masks in Slide Show Software

Summary – Slide show programs derive some of their most powerful effects through the use of layers and masks. In some ways these are no different from those you’d find in Photoshop. In other ways they are very different.

First a simple illustration

It has five layers (and a short sound track, not shown)

Three layers are still images

One layer contains an image used as a mask

One layer contains a video


Figure 1

And here’s the resulting video

Figure 2


Let’s consider the role of layers & masks in creating

A modern multimedia slide show

Masks – serve the same function as they do in

Photoshop (or painting a wall)

They hide parts of what’s behind them

This is the function served by the top layer of Figure 1

Layers – like a stack of cards with images on the front

If the cards are aligned perfectly

The top card hides all of the rest

Note that the mask hides everything below it

Except for the cut-out mask area

This is why it’s at the top of the stack

Spread the cards out and you can see more of them

Upper cards still hide whatever is below, however

This is where Photoshop style layers & slide shows differ

PS layers “blend” and produce a single still image

Slide show layers “move” (pan, zoom, tilt, rotate)

To reveal underlying layers

PS layers don’t change with time (they’re static)

Slide show layer must move else nothing happens


In the above video –

Layer 1 is a mask

Nothing is visible below it except through the “hole”

Layers 2 & 3 are initially behind the mask’s “hole”

They are both moved (L & R) to reveal layer 4

Layer 4 is a video with a sound effect

It pivots and reveals layer 5

Layer 5 is a stationary background image

It’s invisible until the layers above it move

An additional layer, not shown in Figure 1, contains text

It moves after layer 5 is revealed to show a title

The ability to control the timing of the moves described above

Is an essential slide show creation program function

To recap –

Both post-processing and slide show programs use

Layers and masks

Slide shows move layers to create motion (& other video effects)

Post-processing blends layers to create a new still image

Functionally, masks are more or less the same in both

The above video illustrates key layers & masks points

It’s a bit rough in terms of transitions & timing

It’s a first-try to test possibilities

More to come….

Timing of layer adjustments (movements & more)

To get video effects

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