Strobe Writing - Mask Layer

This tutorial uses six images, two words, eleven frames, and one mask layer to create its very simple yet very lively and eye-catching effect.


First, you need to find a number of images and then manipulate them in Flash. All the images should be considerably wider then they are vertical (writing being more often than not a horizontal exercise) and preferably the same size. Bear in mind that they need to cover a large area so don't be surprised if the pictures are 500 pixels wide. I got my images from the web address below:

Open a new movie and change the name of "Layer 1" to "Images." Also add another layer on top of the "Images" layer and name it "Writing Mask." In the first frame of the Images layer, import one of the images you have chosen. You will use Flash to resize the image. Make sure the small Info panel is opened on your screen (Window --> Panels --> Info). This helpful window tells you where and what size your chosen object is. At this time, to make life easier in the future, I would round off both the image’s size and placement as this will make resizing and positioning the other images much easier. In the screen shot above, I have rounded off the width and height to 530 and 190 respectively and centered the image at (9, 3), (x,y) respectively. Once the first image is in place the rest are easy.

Layers & Importing Images (cont.)

On Images Layer’s timeline click on frame 3 and add a keyframe (Right Click>Insert KeyFrame). While in frame 3, click on the image and delete it. Import the next image. Resize it by clicking on the image and then in the Info panel making the image’s width and height, and x and y position the same as the first image's. Repeat this step until you have all your images placed on the timeline. When completed, each picture should play for two frames.

Adding the Mask Layer

Now it is time to make the Mask layer. A mask layer contains a shape through which anything in the layer underneath it appears. In this case, the "shape" is text. The changing images on the layer below the letters pass through them after the movie has been published. Until then, the letters will appear normal. The "shape" or letters in this case become windows to the layer beneath the letters' layer.

With your right mouse button click on “Writing Mask” and choose “mask” from the list of options. You should now have an arrow to the left of the words “Writing Mask” pointing down to “Images.”

Choose the writing tool. Change the font so that it is a preferably a full, thick, and clear font. I have chosen Rockwell Extra Bold. You also want to choose a large font size. Mine is 58. Not only that, I rescaled the text making it taller. The pictures strobe through the letters so if they are too thin, you may lose some effect. That being said, play around with it - you never know!

Make sure the text is centered directly on top of the image underneath it. On the “Writing Mask” Layer timeline, right click on the frame directly above the last frame used in the “Images” Layer and choose “Insert Frame.” Lock the Writing Mask layer.

Trim the stage so that it does not extend beyond your image (Modify>Movie). I edited my height to 200. I also made my background black.

Conclusion and Note

Playing the movie at this point should work.

One last note. In its present state, i.e. using the main timeline of the movie, the movie will loop endlessly and it is of course the endless looping that changes the image through the text every two frames. There may be a time where you want to place this effect in a movie instance where, unless otherwise instructed, it will not repeat. In the “Writing Mask” layer, place a keyframe above the last used frame of the “Image” Layer. Click with the right mouse on that frame and choose “Actions.” From the list of Basic Actions choose “Go to” and change the information accordingly if you need to.