Adobe® Flash® CS4 Professional filters (graphic effects) let you add interesting visual effects to text, buttons, and movie clips. A feature unique to Flash is that you can animate the filters you apply using motion tweens.

Flash blend modes let you create composite images. Compositing is the process of varying the transparency or color interaction of two or more overlapping objects. Blending modes also add a dimension of control to the opacity of objects and images. You can use Flash blending modes to create highlights or shadows that let details from an underlying image show through, or to colorize a desaturated image.

You animate filters in the Timeline. Objects on separate keyframes joined by a tween have the parameters for corresponding filters tweened on intermediate frames. If a filter does not have a matching filter (a filter of the same type) at the opposite end of the tween, a matching filter is added automatically to ensure that the effect occurs at the end of the animation sequence.

To prevent motion tweens from functioning incorrectly if a filter is missing at one end of the tween, or if filters are applied in a different order at each end, Flash does the following:

• If you apply a motion tween to a movie clip with filters applied to it, when you insert a keyframe at the opposite end of the tween, the movie clip automatically has the same filters, with the same stacking order, on the last frame of the tween as it did at the beginning of the tween.

• If you place movie clips on two different frames with different filters applied to each, and you apply a motion tween between the frames, Flash first processes the movie clip with the most filters. Flash then compares the filters applied to the first movie clip against the filters that the second movie clip uses. If no matching filters are found in the second movie clip, Flash generates a dummy filter with no parameters and the color of the existing filters.

• If a motion tween exists between two keyframes and you add a filter to the object in one keyframe, Flash automatically adds a dummy filter to the movie clip when it reaches the keyframe at the other end of the tween.

• If a motion tween exists between two keyframes and you remove a filter from an object in one keyframe, Flash automatically removes the matching filter from the movie clip when it reaches the keyframe at the other end of the tween.

• If you set filter parameters inconsistently between the beginning and end of a motion tween, Flash applies the filter settings of the starting frame to the interpolated frames. Inconsistent settings occur when the following parameters are set differently between the beginning and end of the tween: knockout, inner shadow, inner glow, and type of gradient glow and gradient bevel.

  For example, if you create a motion tween using the drop shadow filter, and apply a drop shadow with a knockout on the first frame of the tween, and an inner shadow on the last frame of the tween, Flash corrects the inconsistent use of the filter in the motion tween. In this case, Flash applies the filter settings used on the first frame of the tween—a drop shadow with a knockout.

The type, number, and quality of the filters you apply to objects can affect the performance of SWF files as you play them. The more filters you apply to an object, the greater the number of calculations Adobe® Flash® Player must process to correctly display the visual effects you’ve created. Adobe® recommends that you apply a limited number of filters to a given object.

Each filter includes controls that let you adjust the strength and quality of the applied filter. Using lower settings improves performance on slower computers. If you are creating content for playback on a wide range of computers, or are unsure of the computing power available to your audience, set the quality level to Low to maximize playback performance.

Adobe Pixel Bender™ is a programming language developed by Adobe that allows users to create custom filters, effects, and blend modes for use in Flash and After Effects. Pixel Bender is hardware independent and designed to run efficiently on a variety of GPU and CPU architectures automatically.

Pixel Bender developers create filters by writing Pixel Bender code and saving the code in a text file with the file extension pbj. Once written, a Pixel Bender filter can be used by any Flash document. Use ActionScript® 3.0 to load the filter and use its controls.

For more information about working with Pixel Bender in ActionScript, see Programming ActionScript 3.0.

Lee Brimelow has posted several helpful Pixel Bender examples on his blog at http://theflashblog.com/?cat=44.

The following video tutorials demonstrate the use of Pixel Bender filters in Flash:

• Pixel Bender: Custom Filters (9:20)

• Flash Downunder – Pixel Bender filters (15:07)