The Image stimulus allows an image to be presented, which can be a bitmap image from a variety of standard file formats, with an optional transparency mask that can effectively control the shape of the image. The mask can also be derived from an image file, or mathematical form such as a Gaussian.
It is a really good idea to get your image in roughly the size (in pixels) that it will appear on screen to save memory. If you leave the resolution at 12 megapixel camera, as taken from your camera, but then present it on a standard screen at 1680x1050 (=1.6 megapixels) then |PsychoPy| and your graphics card have to do an awful lot of unnecessary work. There is a performance advantage (in terms of milliseconds) to using images which are square and powers of two (32, 64, 128, etc.), but this is slight and would not be noticed in the majority of experiments.
Images can have their position, orientation, size and other settings manipulated on a frame-by-frame basis.
Stimuli
PsychoPy, PsychoJS
Everything in a PsychoPy® experiment needs a unique name. The name should contain only letters, numbers and underscores (no punctuation marks or spaces).
The time that the stimulus should first appear. See Defining the onset/duration of components for details.
Governs the duration for which the stimulus is presented. See Defining the onset/duration of components for details.
A filename or a standard name (sin, sqr). Filenames can be relative or absolute paths and can refer to most image formats (e.g. tif, jpg, bmp, png, etc.). If this is set to none, the patch will be a flat colour.
How should the stimulus look? Colour, borders, etc.
If opacity is reduced then the underlying images/stimuli will show through
In what format (color space) have you specified the colors? (rgb, dkl, lms, hsv)
See Color spaces
Foreground color of this stimulus (e.g. $[1,1,0], red )
See Color spaces
Contrast of the stimulus (1.0=unchanged contrast, 0.5=decrease contrast, 0.0=uniform/no contrast, -0.5=slightly inverted, -1.0=totally inverted)
How should the stimulus be laid out? Padding, margins, size, position, etc.
The position of the centre of the stimulus, in the units specified by the stimulus or window
The size of the stimulus in the given units of the stimulus/window. If the mask is a Gaussian then the size refers to width at 3 standard deviations on either side of the mean (i.e. sd=size/6) Set this to be blank to get the image in its native size.
The orientation of the entire patch (texture and mask) in degrees.
Flip the image along the horizontal axis
Flip the image along the vertical axis
Which point on the stimulus should be anchored to its exact position?
Options: - center - top-center - bottom-center - center-left - center-right - top-left - top-right - bottom-left - bottom-right
Units of dimensions for this stimulus
Options: - from exp settings - deg - cm - pix - norm - height - degFlatPos - degFlat
Control how the stimulus handles textures.
A filename, a standard name (gauss, circle, raisedCos) or a numpy array of dimensions NxNx1. The mask can define the shape (e.g. circle will make the patch circular) or something which overlays the patch e.g. noise.
If linear is selected then linear interpolation will be applied when the image is rescaled to the appropriate size for the screen. Nearest will use a nearest-neighbour rule.
This is only needed if you use a synthetic texture (e.g. sinusoidal grating) as the image.
Store the onset/offset times in the data file (as well as in the log file).
Synchronize times with screen refresh (good for visual stimuli and responses based on them)
Disable this Component
Name of validator Component/Routine to use to check the timing of this stimulus.
Options are generated live, so will vary according to your setup.
See also
API reference for ImageStim