This is
my first tutorial so please excuse any mistakes you find..
This tutorial will show you how you could use low resolution brushes
or shapes in a high resolution design. Lets get to it...
First create
a new HIGH resolution page. I created an A4 page with a
300 pixel/inch resolution.

Now choose
any low resolution brush or shape. I am using a low resolution
star shape brush. The brush is actually 29px but I increased it
to a value over 500px.

When you
draw the brush, you will find that it is very distorted because
of the resizing:

This distorsion
can be fixed. Select this drawn brush by ctrl+click the layer
thumbnail. Then click on the channels tab which is next to the
layers tab. Now click on the "Save selection as channel"
button shown bellow:

This will
create an alpha channel with the brush shape. Deselect the star
(ctrl+d) and goto Filter -> Blur -> Gaussian blur and increase
radius until the distorsion isn't clear. I put it as 27px:

After that
we will adjust the levels so the blur is sharpened and the star
comes out clean. Open the levels window by ctrl+L and play with
the 3 arrows (black, grey and white) until you get a clear and
undistorted shape of the star.

Now select
the alpha channel by ctrl and clicking on the thumb nail and then
go back to the layers tab. Create a new layer and fill the selection
with a color. You will get a good high resolution shape of the
star with almost no distortion visible...

Here are
the before and after close ups:

I hope you
enjoyed and learned something from this tutorial.
If you need
any help or want to give comments and suggestions, you can contact
me here.
Peace...
