How could I present an image with fade in and fade out?

[nyessog]

I'd like to present an image with the image appearing progressively
and disappearing progressively too. Could someone tell me how I could
do that?

Thanks

[Michael MacAskill]

Are you using the Builder? If so, the Patch stimulus has an opacity field. Set the button next to it to be "set every frame" so that its value can be changed progressively, and enter an equation in the box that does what you want.

e.g. if your screen refresh rate is 60 Hz, then entering:
frameN/120

would cycle the opacity linearly from 0 to 1.0 over 2s (it will then continue incrementing but it doesn't seem to matter if the value exceeds 1.0).
Using a code component might allow you to do more sophisticated things (e.g. fade in for a while, hold it, then fade out). Or more simply, you just create multiple successive Patch stimulus components, each with a different equation or value in the opacity field depending on their place in the timeline.

Regards,

Michael

[nyessog]

Thank for your response Michael.

I have found the usage of the opacity field.

As soon as I understand how to draw a simple square in PsychoPy I'll update my script but for now here is my script (the script need a picture file).

-----fade-in-out.py-----

# -*- coding: utf-8 -*-

# fade-in-out.py

from psychopy import visual, core

#setup stimulus

win=visual.Window(size=[400, 400], color='white', units='pix')

stim = visual.PatchStim(win, tex='images/stim-200x200/hot1.jpg', mask='none',

    opacity=0.0, name='hot1', autoLog=False)

# Number of steps of the fade phase

fade_steps = 15

# Duration of the fade phase (number of frames)

fade_duration = 60

if fade_steps > fade_duration / 2:

    raise NameError('TooManySteps')

# fade variation at each step (fading from 10% to 100 % and reverse)

delta_fade = 0.9 / fade_steps

# Duration of a step (number of frames)

fade_step_duration = int(fade_duration / fade_steps)

# Duration of the central phase (number of frames)

central_duration = 180

total_presentation_duration = central_duration + 2 * fade_duration

clock = core.Clock()

fade_value = delta_fade

step_stop = fade_step_duration

for frameN in range(total_presentation_duration):

    if frameN < fade_duration:

        if frameN >= step_stop:

            step_stop += fade_step_duration

            fade_value += delta_fade

    elif frameN >= fade_duration + central_duration:

        if frameN >= step_stop:

            step_stop += fade_step_duration

            fade_value -= delta_fade

    else:

        if frameN >= step_stop:

            step_stop = fade_duration + central_duration

            fade_value = 1.0

    stim.opacity = fade_value

    stim.draw()

    win.flip()#flip the screen every frame

[nyessog]

Le lundi 19 mars 2012 12:36:22 UTC+1, nyessog a écrit :

As soon as I understand how to draw a simple square in PsychoPy I'll update my script but for now here is my script (the script need a picture file).

Same script without picture.

-----fade-in-out.py-----

# -*- coding: utf-8 -*-

# fade-in-out.py

#

# This script shows how to present a stimulus with fade in and fade out transition before and after the stimulus

#

from psychopy import visual, core

import numpy as np  # whole numpy lib is available, pre-pend 'np.'

#setup stimulus

win=visual.Window(size=[400, 400], color='white', units='pix')

stim = visual.PatchStim(win, tex=np.array([[-1],[-1]]), mask='none', size=200, opacity=0.0, name='stim', autoLog=False)

[Michael MacAskill]

On 20 Mar, 2012, at 00:36, nyessog wrote:

> As soon as I understand how to draw a simple square in PsychoPy I'll update my script but for now here is my script (the script need a picture file).

Ahh, so you're using Coder and clearly know your way around Python. Could have answered your question in one line then… :–)

Cheers,

Michael

[Jeremy Gray]

I'll add this thread to the "recipes" section of the web documentation
(mostly copy & paste, some editing). It would make a nice addition to
an "Animation" recipe page (along with "scrolling text" from another
thread).

here's the text (will get formatted to look pretty):

https://github.com/jeremygray/psychopy/commit/ceb38a9fd4b514759dba6617a2f5716dcda2f9f2

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[Michael MacAskill]

Hi Jeremy,

Great idea, as this does come up a bit…

I'm not too familiar with the Builder, so I tend to just parrot some variation on "use frameN". But that is quite limited, as it can assume that the stimulus appears at frame 0, and is it tied to the refresh rate.

I wonder if we could collect some tricks for simple one-line animation expressions (i.e. which don't involve a code component). e.g. tracking the mouse position, or a position/colour/opacity value based on a sinusoidal function of elapsed time. I'm not sure what variable names Builder exposes that would be of use?

e.g. I see that there is globalClock.getTime(), but is there also a trial time that resets to zero each repetition, for example? A shopping list of those variables in the documentation would help people along the way. Even for frameN: does it reset each trial, or is it a global frame counter for the entire experiment?

I'll add what I can find to the documentation, but any existing suggestions very welcome.

Mike

On 20 Mar, 2012, at 09:23, Jeremy Gray wrote:

> I'll add this thread to the "recipes" section of the web documentation
> (mostly copy & paste, some editing). It would make a nice addition to
> an "Animation" recipe page (along with "scrolling text" from another
> thread).
>
> here's the text (will get formatted to look pretty):
>
> https://github.com/jeremygray/psychopy/commit/ceb38a9fd4b514759dba6617a2f5716dcda2f9f2

--
Michael R. MacAskill, PhD michael....@nzbri.org
Research Director,
New Zealand Brain Research Institute

66 Stewart St http://www.nzbri.org/macaskill
Christchurch 8011 Ph: +64 3 3786 072
NEW ZEALAND Fax: +64 3 3786 080

[nyessog]

Le lundi 19 mars 2012 21:08:17 UTC+1, Michael MacAskill a écrit :

Ahh, so you're using Coder and clearly know your way around Python.  Could have answered your question in one line then… :–)

I'm new to PsychoPy and Python. These are my first lines of Python but I used other languages before. 

[Gary Lupyan]

You may want to check out my psychopy tutorial / exercises:
http://sapir.psych.wisc.edu/wiki/index.php/Psych711

-----------------------------------------------------
Gary Lupyan - lup...@wisc.edu
Assistant Professor of Psychology
University of Wisconsin, Madison
http://sapir.psych.wisc.edu
-----------------------------------------------------

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[Jonathan Peirce]

On 19/03/2012 21:08, Michael MacAskill wrote:
>
> e.g. I see that there is globalClock.getTime(), but is there also a trial time that resets to zero each repetition, for example? A shopping list of those variables in the documentation would help people along the way. Even for frameN: does it reset each trial, or is it a global frame counter for the entire experiment?
>
> I'll add what I can find to the documentation, but any existing suggestions very welcome.

some of these did get added by Becky to
http://www.psychopy.org/builder/components/code.html
The bottom of that page includes a list of some of the common variables
that people might want to use.

But we could do with more variables described there and more recipes,
maybe as a separate page (or pages) to which the Code Component points.

Jon

--
Jonathan Peirce
Nottingham Visual Neuroscience

http://www.peirce.org.uk

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[nyessog]

Le mardi 20 mars 2012 06:56:17 UTC+1, Gary a écrit :

You may want to check out my psychopy tutorial / exercises:
http://sapir.psych.wisc.edu/wiki/index.php/Psych711

Thanks for the link. Your tutorial make references to files that are not accessible. Could you put an archive with the needed files (perhaps in the installation part)?  

[Michael MacAskill]

On 20 Mar, 2012, at 23:13, Jonathan Peirce wrote:

> some of these did get added by Becky to
> http://www.psychopy.org/builder/components/code.html
> The bottom of that page includes a list of some of the common variables that people might want to use.

Ah, that's exactly what I meant, and in retrospect the code component was the obvious place to look... But people will often want to know about these variables to make full use of the standard components, even when they don't have the need for a code component per se (and so also won't be looking there in the help documents). So perhaps the documentation for each relevant component could have an explicit link to that section, saying something like "The attributes of this stimulus can be modified in real time as a function of a number of variables, as explained here…" It might forestall a lot of common questions.

Cheers,

Regards,

Michael