Contrast Adjustment

I was surprised that MM2 provided a brightness adjustment
but no contrast adjustment in the standard effects. I read
the article "Creating Custom Effects and Transitions in
Windows Movie Maker" and tried to create my own contrast
adjustment in an xml file. My xml file looks like this:

<TransitionsAndEffects Version="1.0" >
<Effects>
<EffectDLL guid="{B4DC8DD9-2CC1-4081-9B2B-
20D7030234EF}">
<Effect name="Contrast +10" iconid="20"
comment="Increase Contrast by 10%">
<Param name="InternalName" value="Standard" />
<Param name="Contrast" value="1.1" />
</Effect>
</EffectDLL>
</Effects>
</TransitionsAndEffects>

The article states that "Contrast adjustment shifts the
range of each color channel around a midpoint. These
values should be greater than or equal to zero, and are
usually around 1.0." I do not know exactly what this
means. I guessed that a value of 1.1 would increase the
contrast by 10%, but I could be entirely wrong here.

At any rate, the xml file loads just fine and I see
the "Contrast +10" effect listed in the effects, however,
if I apply this contrast to a video clip I can see no
difference. I tried values of 2, 20, 200, and 2000000
(just to be crazy) and saw no visible difference in the
video clip.

I think perhaps I am confused about how the tags work
together to construct an effect or a transition. If
someone has successfully created a contrast adjustment,
would you be willing to share the solution. I appreciate
it. Thanks. Ken