White Noise Background

Description

White noise background stimulus.

Fills the display with random noise drawn from a uniform distribution. The experiment can re-randomize the noise via the Randomize White Noise Background action.

Signature

stimulus/white_noise_background

Optional Parameters

grayscale

Default

YES

If YES, all three color channels (red, green, and blue) of a given noise grain will be assigned the same random value. If NO, each color channel will be set to an independent random value, thereby producing colored noise.

grain_size

Default

0.0

Noise grain size (degrees).

The number of grains in each dimension is rounded to the nearest integer. Grain sizes less than or equal to the size of one pixel will result in per-pixel randomization.

rand_seed

Seed value for the random number generator. If omitted, the current system time in nanoseconds is used.

randomize_on_draw

Default

NO

If YES, the stimulus will re-randomize itself every time it draws. Drawing may be triggered either explicitly (via an Update Stimulus Display action) or implicitly (e.g. at the request of a running dynamic stimulus).

To generate dynamic white noise that updates on every display refresh, use this parameter in conjuction with a Frame List Stimulus:

frame_list dynamic_noise (
    stimulus_group = dynamic_noise_frames
    loop = true
    autoplay = true
    )

stimulus_group dynamic_noise_frames {
    white_noise_background (
        randomize_on_draw = true
        )
}

deferred

Options
no
yes
explicit
Default

no

Controls when the stimulus is loaded. If no, the stimulus is loaded at experiment load time. If yes, the stimulus is loaded the first time it is queued. If explicit, the stimulus must be loaded explictly with Load Stimulus.