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 (
    loop = true
    autoplay = true
    ) {
    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.

display¶

Name of the display on which the stimulus will be presented. If omitted, the default display (if available) will be used.

schematic¶

Example:: {'color': [0.2, 0.5, 0.8], 'line_width': 3}

This parameter has no influence on how the stimulus is presented on the stimulus display. Instead, it affects how the schematic for the stimulus appears on MWClient’s eye window.

If present, the parameter’s value must be a dictionary containing one or more of the following keys:

'color': Color of the schematic. The value must be a list of three numbers between 0 and 1 (inclusive), respresenting the red, green, and blue components of the desired color.
'line_width': Width, in display points, of the lines used to draw the schematic. The value must be a non-negative number. A value of zero means the lines should be as thin as possible.
'hidden': Visibility of the schematic. The value must be a boolean, where false means the schematic should be visible, and true means it should be hidden.
'fixation_window': Parameters for the schematic of a fixation point’s fixation window. The value must be a dictionary containing one or more of the preceding keys. (Note: For fixation points, by default the eye window draws a schematic for the fixation window but not the visible stimulus. To show the visible stimulus, include key 'hidden' with a false value at the top level of the schematic dictionary.)

Placement¶

Allowed at top level:	Yes
Allowed parent:	Compound Stimulus, Folder, Frame List Stimulus, Layer Stimulus, List Replicator, Movie Stimulus, Range Replicator, Stimulus Group