Question: **Update**

> 
> This looks now like it was a bug in Mathematica version 8, because
>  everything works as expected - at least for this minimal example - in
>  version 9. (As an aside, I couldn't seem to find the Creative
>  stylesheets using the menu interface, although they're still installed
>  at
>  "/Applications/Mathematica.app/SystemFiles/FrontEnd/StyleSheets/Creative/"
>  (on Mac OS X). Perhaps I accidentally did something to hide them...
> 
> 
> 

I finally tracked down a weird problem I was having with Export and other image-related operations to the type of stylesheet I was using. Consider the same expression evaluated in three different notebooks:

```
ImageDimensions[Rasterize["Mathematica"]]

```

![enter image description here](https://i.stack.imgur.com/TsH0j.png)

You can see that, with the fancier stylesheets, the graphics of the notebook have interacted with the graphics produced by the Mathematica expression.

Is there a work round for this?

Here's another example - exporting a video using the Creative/PrimaryColor stylesheet.

```
grafik = Manipulate[ 
  Graphics3D[{Blue, Cuboid[{0, 0, 0}, {1, 1, 1}]}, Boxed -> False, 
   SphericalRegion -> True, 
   ViewPoint -> {12 Cos[t],  12 Sin[t], 6 Sin[t]}],  {t, 0 , 2 Pi, 
   Pi/24}]
Export["/tmp/grafix.mov", grafik]

```

![stylesheet problems 2](https://i.stack.imgur.com/oYiIc.png)

When the resulting movie is viewed in a movie player, you can see the orange outline and the original graphical frame:

![stylesheet problems 3](https://i.stack.imgur.com/ASM6a.png)

Answer: 
Here's a workaround for your first example. I don't know how robust it is, or if there are any nasty side effects.

```
Block[{StyleDefinitions},
 StyleDefinitions /: StyleDefinitions -> _ = StyleDefinitions -> "Default.nb";
 Rasterize["Mathematica"]]

```
(An extended comment rather than an answer)

This question is strongly related to these two:

* [Rasterize uses default stylesheet if ImageSize is specified](https://mathematica.stackexchange.com/q/36689/280)
* [Default styles for Exporting to PDF, EPS and SVG](https://mathematica.stackexchange.com/q/139948/280)

As I've found during working on the answer to the latter question, there is inconsistency in styles used for `Export`ing to raster and vector formats:

* when `Export`ing to raster formats, `StyleDefinitions` of the `EvaluationNotebook[]` are used
* when `Export`ing to vector formats, `DefaultStyleDefinitions` (global `$FrontEndSession` option) are used

At the first step `Export` creates a `Notebook` from the expression supplied, and then sends this Notebook to the FrontEnd for conversion. In the case of raster formats this Notebook expression already contains the following options:

```
AbsoluteOptions[EvaluationNotebook[], {Evaluator, StyleDefinitions, WindowSize}]

```

A proof (output is from version 11.2.0):

```
Trace[ExportString["Mathematica", "MGF"], 
   CurrentValue | AbsoluteOptions | EvaluationNotebook] //. {{x___}} :> {x}

```

> 
> 
> ```
> {{AbsoluteOptions[$FrontEndSession,CommonDefaultFormatTypes]},
> {{EvaluationNotebook[],MathLink`CallFrontEnd[FrontEnd`EvaluationNotebook[]]},
> {AbsoluteOptions[NotebookObject[Untitled-1],{Evaluator,StyleDefinitions,WindowSize}]}}}
> 
> ```
> 
>