BufferImageStim
¶BufferImageStim (win[, buffer, rect, ...]) |
Take a “screen-shot”, save as an ImageStim (RBGA object). |
BufferImageStim.win |
The Window object in which the stimulus will be rendered by default. |
BufferImageStim.buffer |
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BufferImageStim.rect |
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BufferImageStim.stim |
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BufferImageStim.mask |
The alpha mask that can be used to control the outer |
BufferImageStim.units |
None, ‘norm’, ‘cm’, ‘deg’, ‘degFlat’, ‘degFlatPos’, or ‘pix’ |
BufferImageStim.pos |
The position of the center of the stimulus in the stimulus |
BufferImageStim.ori |
The orientation of the stimulus (in degrees). |
BufferImageStim.size |
The size (width, height) of the stimulus in the stimulus |
BufferImageStim.contrast |
A value that is simply multiplied by the color |
BufferImageStim.color |
Color of the stimulus |
BufferImageStim.colorSpace |
The name of the color space currently being used |
BufferImageStim.opacity |
Determines how visible the stimulus is relative to background |
BufferImageStim.interpolate |
Whether to interpolate (linearly) the texture in the stimulus |
BufferImageStim.name |
String or None. |
BufferImageStim.autoLog |
Whether every change in this stimulus should be auto logged. |
BufferImageStim.draw ([win]) |
Draws the BufferImage on the screen, similar to ImageStim .draw(). |
BufferImageStim.autoDraw |
Determines whether the stimulus should be automatically drawn on every frame flip. |
psychopy.visual.
BufferImageStim
(win, buffer='back', rect=(-1, 1, 1, -1), sqPower2=False, stim=(), interpolate=True, flipHoriz=False, flipVert=False, mask='None', pos=(0, 0), name=None, autoLog=None)¶Take a “screen-shot”, save as an ImageStim (RBGA object).
The screen-shot is a single collage image composed of static elements that you can treat as being a single stimulus. The screen-shot can be of the visible screen (front buffer) or hidden (back buffer).
BufferImageStim aims to provide fast rendering, while still allowing dynamic orientation, position, and opacity. It’s fast to draw but slower to init (same as an ImageStim).
You specify the part of the screen to capture (in norm units), and optionally the stimuli themselves (as a list of items to be drawn). You get a screenshot of those pixels. If your OpenGL does not support arbitrary sizes, the image will be larger, using square powers of two if needed, with the excess image being invisible (using alpha). The aim is to preserve the buffer contents as rendered.
Checks for OpenGL 2.1+, or uses square-power-of-2 images.
Example:
# define lots of stimuli, make a list:
mySimpleImageStim = ...
myTextStim = ...
stimList = [mySimpleImageStim, myTextStim]
# draw stim list items & capture (slow; see EXP log for times):
screenshot = visual.BufferImageStim(myWin, stim=stimList)
# render to screen (very fast, except for the first draw):
while <conditions>:
screenshot.draw() # fast; can vary .ori, .pos, .opacity
other_stuff.draw() # dynamic
myWin.flip()
See coder Demos > stimuli > bufferImageStim.py for a demo, with timing stats.
Author: |
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Parameters: |
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autoDraw
¶Determines whether the stimulus should be automatically drawn on every frame flip.
Value should be: True or False. You do NOT need to set this on every frame flip!
autoLog
¶Whether every change in this stimulus should be auto logged.
Value should be: True or False. Set to False if your stimulus is updating frequently (e.g. updating its position every
frame) and you want to avoid swamping the log file with
messages that aren’t likely to be useful.
clearTextures
()¶Clear all textures associated with the stimulus.
As of v1.61.00 this is called automatically during garbage collection of your stimulus, so doesn’t need calling explicitly by the user.
color
¶Color of the stimulus
string: to specify a Colors by name. Any of the standard html/X11 color names <http://www.w3schools.com/html/html_colornames.asp> can be used.
other Color spaces. For these, operations are supported.
When color is specified using numbers, it is interpreted with respect to the stimulus’ current colorSpace. If color is given as a single value (scalar) then this will be applied to all 3 channels.
# ... for whatever stim you have: stim.color = ‘white’ stim.color = ‘RoyalBlue’ # (the case is actually ignored) stim.color = ‘#DDA0DD’ # DDA0DD is hexadecimal for plum stim.color = [1.0, -1.0, -1.0] # if stim.colorSpace=’rgb’:
# a red color in rgb space
Operations work as normal for all numeric colorSpaces (e.g. ‘rgb’, ‘hsv’ and ‘rgb255’) but not for strings, like named and hex. For example, assuming that colorSpace=’rgb’:
stim.color += [1, 1, 1] # increment all guns by 1 value
stim.color *= -1 # multiply the color by -1 (which in this
# space inverts the contrast)
stim.color *= [0.5, 0, 1] # decrease red, remove green, keep blue
You can use setColor if you want to set color and colorSpace in one line. These two are equivalent:
stim.setColor((0, 128, 255), 'rgb255')
# ... is equivalent to
stim.colorSpace = 'rgb255'
stim.color = (0, 128, 255)
colorSpace
¶The name of the color space currently being used
Value should be: a string or None
For strings and hex values this is not needed. If None the default colorSpace for the stimulus is used (defined during initialisation).
Please note that changing colorSpace does not change stimulus parameters. Thus you usually want to specify colorSpace before setting the color. Example:
# A light green text
stim = visual.TextStim(win, 'Color me!',
color=(0, 1, 0), colorSpace='rgb')
# An almost-black text
stim.colorSpace = 'rgb255'
# Make it light green again
stim.color = (128, 255, 128)
contains
(x, y=None, units=None)¶Returns True if a point x,y is inside the stimulus’ border.
two separate args, x and y
one arg (list, tuple or array) containing two vals (x,y)
as a Mouse
.
Returns True if the point is within the area defined either by its border attribute (if one defined), or its vertices attribute if there is no .border. This method handles complex shapes, including concavities and self-crossings.
Note that, if your stimulus uses a mask (such as a Gaussian) then this is not accounted for by the contains method; the extent of the stimulus is determined purely by the size, position (pos), and orientation (ori) settings (and by the vertices for shape stimuli).
See Coder demos: shapeContains.py See Coder demos: shapeContains.py
contrast
¶A value that is simply multiplied by the color
Set the contrast of the stimulus, i.e. scales how far the stimulus deviates from the middle grey. You can also use the stimulus opacity to control contrast, but that cannot be negative.
Examples:
stim.contrast = 1.0 # unchanged contrast
stim.contrast = 0.5 # decrease contrast
stim.contrast = 0.0 # uniform, no contrast
stim.contrast = -0.5 # slightly inverted
stim.contrast = -1.0 # totally inverted
Setting contrast outside range -1 to 1 is permitted, but may produce strange results if color values exceeds the monitor limits.:
stim.contrast = 1.2 # increases contrast
stim.contrast = -1.2 # inverts with increased contrast
depth
¶DEPRECATED. Depth is now controlled simply by drawing order.
draw
(win=None)¶Draws the BufferImage on the screen, similar to
ImageStim
.draw().
Allows dynamic position, size, rotation, mirroring, and opacity.
Limitations / bugs: not sure what happens with shaders and
self._updateList()
flipHoriz
¶If set to True then the image will be flipped horizontally (left-to-right). Note that this is relative to the original image, not relative to the current state.
flipVert
¶If set to True then the image will be flipped vertically (left-to-right). Note that this is relative to the original image, not relative to the current state.
image
¶The image file to be presented (most formats supported).
interpolate
¶Whether to interpolate (linearly) the texture in the stimulus
If set to False then nearest neighbour will be used when needed, otherwise some form of interpolation will be used.
mask
¶The alpha mask that can be used to control the outer shape of the stimulus
- None, ‘circle’, ‘gauss’, ‘raisedCos’
- or the name of an image file (most formats supported)
- or a numpy array (1xN or NxN) ranging -1:1
maskParams
¶Various types of input. Default to None.
This is used to pass additional parameters to the mask if those are needed.
- For ‘gauss’ mask, pass dict {‘sd’: 5} to control
standard deviation.
- For the ‘raisedCos’ mask, pass a dict: {‘fringeWidth’:0.2},
where ‘fringeWidth’ is a parameter (float, 0-1), determining the proportion of the patch that will be blurred by the raised cosine edge.
name
¶String or None. The name of the object to be using during logged messages about this stim. If you have multiple stimuli in your experiment this really helps to make sense of log files!
If name = None your stimulus will be called “unnamed <type>”, e.g. visual.TextStim(win) will be called “unnamed TextStim” in the logs.
opacity
¶Determines how visible the stimulus is relative to background
The value should be a single float ranging 1.0 (opaque) to 0.0 (transparent). Operations are supported. Precisely how this is used depends on the Blend Mode.
ori
¶The orientation of the stimulus (in degrees).
Should be a single value (scalar). Operations are supported.
Orientation convention is like a clock: 0 is vertical, and positive values rotate clockwise. Beyond 360 and below zero values wrap appropriately.
overlaps
(polygon)¶Returns True if this stimulus intersects another one.
If polygon is another stimulus instance, then the vertices and location of that stimulus will be used as the polygon. Overlap detection is typically very good, but it can fail with very pointy shapes in a crossed-swords configuration.
Note that, if your stimulus uses a mask (such as a Gaussian blob) then this is not accounted for by the overlaps method; the extent of the stimulus is determined purely by the size, pos, and orientation settings (and by the vertices for shape stimuli).
See coder demo, shapeContains.py
pos
¶The position of the center of the stimulus in the stimulus units
value should be an x,y-pair. Operations are also supported.
Example:
stim.pos = (0.5, 0) # Set slightly to the right of center
stim.pos += (0.5, -1) # Increment pos rightwards and upwards.
Is now (1.0, -1.0)
stim.pos *= 0.2 # Move stim towards the center.
Is now (0.2, -0.2)
Tip: If you need the position of stim in pixels, you can obtain it like this:
from psychopy.tools.monitorunittools import posToPix posPix = posToPix(stim)
setAutoDraw
(value, log=None)¶Sets autoDraw. Usually you can use ‘stim.attribute = value’ syntax instead, but use this method to suppress the log message.
setAutoLog
(value=True, log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message.
setColor
(color, colorSpace=None, operation='', log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message and/or set colorSpace simultaneously.
setContrast
(newContrast, operation='', log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message
setDKL
(newDKL, operation='')¶DEPRECATED since v1.60.05: Please use the color attribute
setDepth
(newDepth, operation='', log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message
setFlipHoriz
(newVal=True, log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message.
setFlipVert
(newVal=True, log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message.
setImage
(value, log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message.
setLMS
(newLMS, operation='')¶DEPRECATED since v1.60.05: Please use the color attribute
setMask
(value, log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message.
setOpacity
(newOpacity, operation='', log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message
setOri
(newOri, operation='', log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message
setPos
(newPos, operation='', log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message.
setRGB
(newRGB, operation='', log=None)¶DEPRECATED since v1.60.05: Please use the color attribute
setSize
(newSize, operation='', units=None, log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message
setUseShaders
(value=True, log=None)¶Usually you can use ‘stim.attribute = value’ syntax instead, but use this method if you need to suppress the log message
size
¶The size (width, height) of the stimulus in the stimulus units
Value should be x,y-pair, scalar (applies to both dimensions) or None (resets to default). Operations are supported.
Sizes can be negative (causing a mirror-image reversal) and can extend beyond the window.
Example:
stim.size = 0.8 # Set size to (xsize, ysize) = (0.8, 0.8)
print(stim.size) # Outputs array([0.8, 0.8])
stim.size += (0.5, -0.5) # make wider and flatter: (1.3, 0.3)
Tip: if you can see the actual pixel range this corresponds to by looking at stim._sizeRendered
texRes
¶Power-of-two int. Sets the resolution of the mask and texture. texRes is overridden if an array or image is provided as mask.
Operations supported.
units
¶None, ‘norm’, ‘cm’, ‘deg’, ‘degFlat’, ‘degFlatPos’, or ‘pix’
If None then the current units of the
Window
will be used.
See Units for the window and stimuli for explanation of other options.
Note that when you change units, you don’t change the stimulus parameters and it is likely to change appearance. Example:
# This stimulus is 20% wide and 50% tall with respect to window
stim = visual.PatchStim(win, units='norm', size=(0.2, 0.5)
# This stimulus is 0.2 degrees wide and 0.5 degrees tall.
stim.units = 'deg'
useShaders
¶Should shaders be used to render the stimulus (typically leave as True)
If the system support the use of OpenGL shader language then leaving this set to True is highly recommended. If shaders cannot be used then various operations will be slower (notably, changes to stimulus color or contrast)
verticesPix
¶This determines the coordinates of the vertices for the current stimulus in pixels, accounting for size, ori, pos and units
win
¶Window
object in which theExample, drawing same stimulus in two different windows and display simultaneously. Assuming that you have two windows and a stimulus (win1, win2 and stim):
stim.win = win1 # stimulus will be drawn in win1
stim.draw() # stimulus is now drawn to win1
stim.win = win2 # stimulus will be drawn in win2
stim.draw() # it is now drawn in win2
win1.flip(waitBlanking=False) # do not wait for next
# monitor update
win2.flip() # wait for vertical blanking.
Note that this just changes **default** window for stimulus.
You could also specify window-to-draw-to when drawing::
stim.draw(win1)
stim.draw(win2)