[visionegg] Re: Adding noise to screen

Hi,

How does the display need to look?  IF it's a matter of putting noise over
part of the screen (like over text displayed in the center), I might be able
to dig up an old script I tried out that worked well.  Basically, you get
5-10 tall narrow images (.jpg, .bmp) of noise/snow, then place them side by
side over the text with a low opacity AND randomize the y value for the
anchor(leaving x constant, so you don't have overlapping semi-opaque blocks
of noise).  Finally, to make things neat looking, you just "frame" the text
with some stationary fully opaque rectangles laid over top of the moving
noise images, (usually whatever the background color is).
In this set up, you could have different opacities for each "strip" of
noise, or e.g. fix the x values to gaze if you're doing an eye tracking
experiment.
If I remember right, this method CAN work for a whole screen, but you need
to make compromises on how long the strips are (i.e. the variety of the
noise), and things would probably go too slow to e.g. have mouse or
eye-position -related movement of noise be convincing.

-Dave

On Thu, Jul 10, 2008 at 11:59 PM, Rafael Fernandez <rfernan3@xxxxxxxxxxxx>
wrote:

> Hello,
> I am trying to add noise over a display. I am currently creating
> TextureStimulus objects randomly all over the screen. However, this is VERY
> slow. Does anyone have any idea on how to achieve this?
>
> Thank you,
> Rafael Fernández
>
> --
> Rafael E. Fernández
> Computer Science major
> University of Illinois at Urbana-Champaign
>

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