The BlurFilter class lets you apply a blur visual effect to display
objects. A blur effect softens the details of an image. You can produce
blurs that range from a softly unfocused look to a Gaussian blur, a hazy
appearance like viewing an image through semi-opaque glass. When the
quality property of this filter is set to low, the result is a
softly unfocused look. When the
quality property is set to
high, it approximates a Gaussian blur filter. You can apply the filter to
any display object(that is, objects that inherit from the DisplayObject
class), such as MovieClip, SimpleButton, TextField, and Video objects, as
well as to BitmapData objects.
To create a new filter, use the constructor
BlurFilter(). The use of filters depends on the object to which you
apply the filter:
- To apply filters to movie clips, text fields, buttons, and video, use
filtersproperty(inherited from DisplayObject). Setting the
filtersproperty of an object does not modify the object, and you can remove the filter by clearing the
- To apply filters to BitmapData objects, use the
applyFilter()on a BitmapData object takes the source BitmapData object and the filter object and generates a filtered image as a result.
If you apply a filter to a display object, the
cacheAsBitmap property of the display object is set to
true. If you remove all filters, the original value of
cacheAsBitmap is restored.
This filter supports Stage scaling. However, it does not support general
scaling, rotation, and skewing. If the object itself is scaled
scaleY are not set to 100%), the
filter effect is not scaled. It is scaled only when the user zooms in on
A filter is not applied if the resulting image exceeds the maximum dimensions. In AIR 1.5 and Flash Player 10, the maximum is 8,191 pixels in width or height, and the total number of pixels cannot exceed 16,777,215 pixels.(So, if an image is 8,191 pixels wide, it can only be 2,048 pixels high.) In Flash Player 9 and earlier and AIR 1.1 and earlier, the limitation is 2,880 pixels in height and 2,880 pixels in width. If, for example, you zoom in on a large movie clip with a filter applied, the filter is turned off if the resulting image exceeds the maximum dimensions.
Initializes the filter with the specified parameters. The default values create a soft, unfocused image.
The amount to blur horizontally. Valid values are from 0 to 255.0(floating-point value).
The amount to blur vertically. Valid values are from 0 to 255.0(floating-point value).
The number of times to apply the filter. You can specify the quality using the BitmapFilterQuality constants:
High quality approximates a Gaussian blur. For most applications, these three values are sufficient. Although you can use additional numeric values up to 15 to achieve different effects, be aware that higher values are rendered more slowly.
The amount of horizontal blur. Valid values are from 0 to 255(floating point). The default value is 4. Values that are a power of 2(such as 2, 4, 8, 16 and 32) are optimized to render more quickly than other values.
The amount of vertical blur. Valid values are from 0 to 255(floating point). The default value is 4. Values that are a power of 2(such as 2, 4, 8, 16 and 32) are optimized to render more quickly than other values.
The number of times to perform the blur. The default value is
BitmapFilterQuality.LOW, which is equivalent to applying the
filter once. The value
BitmapFilterQuality.MEDIUM applies the
filter twice; the value
BitmapFilterQuality.HIGH applies it
three times and approximates a Gaussian blur. Filters with lower values
are rendered more quickly.
For most applications, a
quality value of low, medium, or
high is sufficient. Although you can use additional numeric values up to
15 to increase the number of times the blur is applied, higher values are
rendered more slowly. Instead of increasing the value of
quality, you can often get a similar effect, and with faster
rendering, by simply increasing the values of the
You can use the following BitmapFilterQuality constants to specify
values of the