Flash Performance Series: “Quality Adjustments”

Quality adjustment:

In already-finished proyects, the largest(and easiest) performance gains in Flash are to be made by adjusting the overall quality of the renderer, because this practice doesnt require to change anything inside the proyect.

In the ideal case, Quality settings should be left in the highest possible setting so the app would take advantage of flash´s clear and well-defined graphics, Therefore lowering the overall quality must be a last resort after all other possible optimizations have been done.

Flash quality adjustments affect primarily image Anti-Aliasing(covered next), which is a time consuming but rewarding visual effect applied to everything that Flash renders.

NOTE: Flash´s default display quality is “HIGH”;

Flash Anti-aliasing:

Anti-aliasing(AA) works in the same way for flash as it does for other applications. It consists in a complex process of adding mid tone pixels to the jagged edges of images or text so the human eye will perceive a smoother image instead of jagged lines that look like a ladder.

In this process, the platform calculates the pixels that are on the edges of lines and “smooths” them by adding more pixels of different colors (usually an average between line color and background).

Highest levels of AA in more complicated applications even tune alpha values in these pixels to further increase the (apparent) quality of the lines. Complicated as it is, this process is costly for the CPU, and adds lots of work to the rendering cycles. This applies to both image and text rendering.

Anti-Aliasing (quality) levels:

•StageQuality.LOW—Low rendering quality. Graphics are not anti-aliased, and bitmaps are not smoothed.

•StageQuality.MEDIUM—Medium rendering quality. Graphics are anti-aliased using a 2 x 2 pixel grid, but bitmaps are not smoothed.

•StageQuality.HIGH—High rendering quality. Graphics are anti-aliased using a 4 x 4 pixel grid, and bitmaps are smoothed if the movie is static.

•StageQuality.BEST—Very high rendering quality. Graphics are anti-aliased using a 4 x 4 pixel grid and bitmaps are always smoothed.

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