[R-SIG-Mac] strange interaction of quartz() with videoprojector

[Simon Urbanek]

On May 5, 2008, at 4:36 AM, Kenneth Knoblauch wrote:

> A setting of dpi = 1.5 * 72 generates about the right size graphics  
> and alleviates the light lines problem, which must have been from  
> the antialiasing, as you proposed.
>

1.5*72 is ca. 100 dpi which most displays use. Clearly on a projector  
DPI is not very meaningful since it varies with the projected distance.


> This seems to be related to the automatic selection of resolution in  
> System Preferences for Displays.  The values chosen automatically  
> which generated the small quartz windows are set at 1280 x 1024.  At  
> one point, restarting the machine while connected to the  
> videoprojector, it started up with a lower resolution and the quartz  
> window worked fine.  I wasn't able to reproduce this though by  
> manually reducing the resolution in the preferences.  I have to  
> experiment a bit more to see how to get it to start up automatically  
> in the lower resolution, which would seem to obviate the problem for  
> the short term.
>

FWIW in most cases what you call "automatic" is not very helpful.  
Fortunately the Display settings are smart and will remember the last  
used modes, so if you set up the correct resolution, it will be  
remembered and you can restore it with one click. In most cases I  
recommend using projector's native resolution as it is the only  
resolution that is faithfully represented.

(This is not really Quartz-related, it hold true for any projection  
with the possible exception of video projection).

Cheers,
Simon

>
>
> Quoting Prof Brian Ripley <ripley at stats.ox.ac.uk>:
>
>> You can set the quartz() argument 'dpi'.  I'm not sure why this is
>> being detected wrongly, but it looks as if it is.
>>
>> On Mon, 5 May 2008, Kenneth Knoblauch wrote:
>>
>>> Hi,
>>>
>>> The new graphics window defaults in R 2.7.0 are great but I've
>>> noticed a strange phenomenon when I'm using R with my MacBook Pro
>>> connected to a videoprojector.  Under these conditions,
>>> the quartz window that is opened is tiny,
>>> about 1/5 the default size and the line colors are a light
>>> grey (or a light color, at least.  Not 100% sure that it is grey).
>>
>> This could be the effect of antialiasing on narrow lines.
>>
>>> As soon as I detach the videoprojector and reset the
>>> display size, everything returns to normal.
>>>
>>> The minimal example would be to hook up your portable to
>>> a videoprojector, start R and run
>>>
>>> quartz()
>>>
>>> Does anyone else see this?
>>>
>>> I can get the normal default with
>>>
>>> quartz(width = 30, height = 30)
>>>
>>> but the text and points are very small.  I can get around this
>>> with cex and col arguments but this is not optimal.  Not great
>>> for teaching.
>>>
>>> Thank you for any suggestions.  SessionInfo below.
>>>
>>> Ken
>>>
>>>
>>>
>>> R version 2.7.0 Patched (2008-04-30 r45572)
>>> i386-apple-darwin8.10.1
>>>
>>> locale:
>>> en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
>>>
>>> attached base packages:
>>> [1] stats     graphics  grDevices utils     datasets  methods   base
>>>
>>>
>>> -- 
>>> Ken Knoblauch
>>> Inserm U846
>>> Institut Cellule Souche et Cerveau
>>> Département Neurosciences Intégratives
>>> 18 avenue du Doyen Lépine
>>> 69500 Bron
>>> France
>>> tel: +33 (0)4 72 91 34 77
>>> fax: +33 (0)4 72 91 34 61
>>> portable: +33 (0)6 84 10 64 10
>>> http://www.sbri.fr
>>>
>>> _______________________________________________
>>> R-SIG-Mac mailing list
>>> R-SIG-Mac at stat.math.ethz.ch
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>>
>> -- 
>> Brian D. Ripley,                  ripley at stats.ox.ac.uk
>> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
>> University of Oxford,             Tel:  +44 1865 272861 (self)
>> 1 South Parks Road,                     +44 1865 272866 (PA)
>> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>
>
>
> -- 
> Ken Knoblauch
> Inserm U846
> Institut Cellule Souche et Cerveau
> Département Neurosciences Intégratives
> 18 avenue du Doyen Lépine
> 69500 Bron
> France
> tel: +33 (0)4 72 91 34 77
> fax: +33 (0)4 72 91 34 61
> portable: +33 (0)6 84 10 64 10
> http://www.sbri.fr
>
> _______________________________________________
> R-SIG-Mac mailing list
> R-SIG-Mac at stat.math.ethz.ch
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