presentation of movies in full screen

Wed Mar 20 09:59:56 UTC 2013

Hi,

The reason is pretty similar to the common problem in resizing: there’s only
so many pixels. Imagine you have 5x5 pixels and want to draw an X:

10001

01010

00100

01010

10001

Would be more or less it (imagine 1 being a different colour from 0). Now,
resizing it by a factor of two shouldn’t be too hard:

1100000011

1100000011

0011001100

0011001100

0000110000

0000110000

0011001100

0011001100

1100000011

1100000011

There, the pixels are just really big now. So, you might as well have used
twice as low a resolution – should be better, performance-wise.

In any case, imagine you wanted to resize by a factor of 1.4 (7x7 pixels)
instead of 2. Without any type of anti-aliasing going on, you could get
something like

1000001

0110110

0110110

0001000

0110110

0110110

1000001

(here, I arbitrarily decided to double pixels 2 and 4, because I’m not sure
how the rounding is handled).

Which rather distorts the beautiful X. Anti-aliasing could diminish the
effect of such distortions by using a type of blurring filter, but as far as
I know, E-Prime doesn’t do this by default. If you want to see the
difference in effect, try copying a smallish image to MSPaint (I did print
screen, start>run>mspaint, copied a screenshot to mspaint, moved everything
out of sight, copied the start logo), then scale everything up by some sort
of factor. Doesn’t look so good… Notice what happens if you scale something
up by a factor, copy the effect you have, then scale it down to previous
size: it looks worse than it did. The results of such a test are attached
(hopefully it gets through, one never knows with groups):

Upper left: start button, original.

Lower left: start button, resized x 2, maintained aspect ratio, resized back
(x 0.5). Looks as good as original.

Upper right: start button resized x 1.5, maintained aspect ratio, resized
back (x ca. 0.67), notice distortion is visible in horizontal line the
windows flag. Upper left (red bit) has become a straight line, the upper
right (green bit) became pixilated. 

Lower right: start button resized a few times, didn’t maintain aspect ratio.
It looks bad.

So, even if you maintain aspect ratio throughout, artifacts are pretty
inevitable and at best you’re just displaying images at a lower resolution.
This makes a certain sense, of course, as the type of enlarging that
actually adds details (CSI style, or so I’m told) hasn’t been invented yet. 

Of course, everything here counts for video images as well as static images,
except for the fact that movement and such hides quite a lot. 

Hope that helps!

Best,

Michiel

From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf
Of Soizic Argaud
Sent: 19. March 2013 20:14
To: e-prime at googlegroups.com
Subject: Re: presentation of movies in full screen

Hi, 

Thank you for your answer. I tried the short one but it didn't work. So I
took your advice (better answer) and I resized my stimuli "out of" E-Prime.
Doing this, it's ok. But I still don't understand why I can't modify easily
the size of my film excerpts in E-Prime.

Best, 

Soizic

2013/3/19 Cognitology <mspape at cognitology.eu>

Hi,

Short answer: Use a moviedisplay, set size to 100% (it’s 75% by default
now), and turn Stretch on. You can keep the aspect ratio (e.g. Stretch mode
LeftRight) as is or distort it into submission (stretch mode Both). 

Better answer: first, find out at which resolution your experiment is
running. Is it widescreen? Is your monitor? What resolution are the movies?
Then, consider re-encoding the movies to fit your resolution; though quite a
few options are possible in E-Prime as outlined above, it makes a certain
amount of sense to be very sure of your stimuli rather than fiddling around
with them at runtime!

Best,

Michiel

From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf
Of Soizic Argaud
Sent: 19. March 2013 16:17
To: e-prime at googlegroups.com; Soizic Argaud
Subject: presentation of movies in full screen

Hello everyone,

I'm a new user of E-Prime and I'm currently creating a task during which I
present different film excerpts to my participants and then, they answer
questionnaires. 

Everything's (nearly) ok but one of the difficulties I encounter is about
the size of the movies. I don't know how to modify it to project the movies
in full screen.

If you can help me to fix this (first) issue, I'll be very grateful.

Thank you very much for your help !

Soizic

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