Expert: Amy - 8/29/2004

Question
I have a shape that I want to blur. I can't use Filter>blur>gaussian. It won't allow me. I CAN use Effect>blur>gaussian blur, but that just desaturates the shape. What is the deal?

Answer
Hi Chris,

The Gaussian blur effect isn't that spectacular at low doses.  On solid colored objects, it mainly affects the edges.  Turn the radius up to 8 or 9 for a bigger blur. To change this, you have to apply a blur "from scratch."  Don't just use the Ctrl+Shift+E command to apply the last-used effect.

Also, an important difference between filters and effects is that effects can be applied and then turned on and off for any selected object in the Appearance Window (Window > Show Appearance).

Now, as to why you can't use the Filter side...
The deal is that Gaussian blur filter is a "PhotoShop filter," a term that applies to several of the Illustrator filters.

To use these filters as filters (not effects), you must be working with a raster image - that is, an imported bitmap image or a vector object that you've rasterized.

So you just have to rasterize your object first:

Select your shape and choose Object>Rasterize.
x choose CMYK or RGB, depending on your doc's color mode
x choose high (300 dpi) or type in an even higher amount.
x choose anti-alias
x if it's overlapping another object in your document, choose transparent, if not, choose white
x make a clipping path if you need to

Click okay and it will convert.  Now you can apply your Gaussian blur filter...

The filter will look the same as the effect version, but it cannot be turned off in the Appearance Window.

Technically, I think that what the *effect* version is doing is creating a raster image from your vector object, then applying the filter and displaying the filtered raster image in place of the original vector object, but not deleting the vector object.

Hope this helped a little!

-Amy