[R] R versions and PostScript files

Thu Jul 21 22:13:25 CEST 2011

Yes, Peter, your suggestion does the trick (at any rate with
Gaetano's files).

I edited his volc2.13.eps (the slow one) as follows (the original
commented out with "%%##") making just the following change:

%%## /setrgb { srgb setcolor } def
/setrgb { setrgbcolor } def
%%## End of editing

(at line 53 of the prologue). The result is a file that produces
exactly the same picture as the other (fast) one, and renders
(to within my perceptual resolution) in exactly the same time,
i.e. just under one second (as opposed to about 18 before).

Thanks, Peter!
Ted.

On 21-Jul-11 18:59:58, peter dalgaard wrote:
> This is due to the introduction of sRGB. Since this actually does
> something (Google for sRGB and you will be approximately as wise as
> me...), I don't think it is likely to be taken out. You can, however,
> always edit .ps.prolog. (I would expect that the line
> 
> /setrgb { setrgbcolor } def
> 
> instead of what is already there would reinstate the old behavior, but
> no guarantees.
> )
> 
> 
> On Jul 21, 2011, at 17:26 , (Ted Harding) wrote:
> 
>> On 21-Jul-11 13:24:32, Duncan Murdoch wrote:
>>> On 11-07-21 3:23 AM, pilchat wrote:
>>>> Dear R users,
>>>> 
>>>> I have a desktop computer and a laptop, both of them
>>>> with Ubuntu Lucid. The former has R2.10 installed from
>>>> Ubuntu repositories (this is the most recent version
>>>> in the repositories), while the latter has R2.13 from
>>>> the CRAN repositories.
>>>> 
>>>> I noticed that postscript files generated with R2.10
>>>> are "better" than files generated with the latest release
>>>> of R, in particular for plots with colored areas, such
>>>> as the output of image or persp. The thing is that my ps
>>>> viewer (e.g. gv or evince) is very slow in opening ps
>>>> files from R2.13, while it smoothly displays ps files
>>>> from R2.10, regardless of "encapsulation".
>>>> 
>>>> I think this is related to differences in the way the
>>>> ps file is generated by the two versions of R, but I
>>>> don't know how to go deeper in the matter.
>>> 
>>> Postscript files are mostly text, so you can compare the
>>> two files and > see what the differences are. The NEWS
>>> file shows a number of changes since 2.10.0, but I can't
>>> see any that would cause problems for viewers.
>>> 
>>> Duncan Murdoch
>>> 
>>>> Is there anyone experiencing the same issue? Is there
>>>> any solution?
>>>> 
>>>> Thank you in advance
>>>> 
>>>> Cheers
>>>> Gaetano
>> 
>> Gaetano has now sent me two files, generated (as he posted
>> just now on R-help) by the same commands:
>> 
>>  setEPS()
>>  postscript (file="volc.eps",width=5,height=4)
>>  image(volcano)
>>  dev.off()
>> 
>> on his two machines:
>> 
>> volc2.10.eps generated using R-2.10 on his desktop
>>  (the EPS file with fast rendering)
>> 
>> volc2.13.eps generated using R-2.13 on his laptop
>>  (the EPS file with slow rendering)
>> 
>> I have viewed both files on the same machine, and the
>> result indeed is that while volc2.10.eps renders very
>> quickly, volc2.13.eps does render very slowly (painting
>> in by vertical strips which move jerkily from left
>> to right). I estimate that 'gv volc2.10.eps' does the
>> rendering in less than 1 second, while 'gv volc2.13.eps'
>> takes about 18 seconds.
>> 
>> Comparing the two files, I think I have found the reason.
>> 
>> A 'diff' on the two files shows a basic difference in
>> definitions of a function used in the plotting:
>> 
>> [A] In file volc2.10.eps (the fast one):
>> 
>>  /rgb { setrgbcolor } def
>> 
>> [B] In file volc2.13.eps (the slow one):
>> 
>>  /srgb { [ /CIEBasedABC
>>            << /DecodeLMN
>>                 [ { dup 0.03928 le
>>                          {12.92321 div}
>>                          {0.055 add 1.055 div 2.4 exp }
>>                       ifelse
>>                   } bind dup dup
>>                 ]
>>               /MatrixLMN [0.412457 0.212673 0.019334
>>                           0.357576 0.715152 0.119192
>>                           0.180437 0.072175 0.950301]
>>               /WhitePoint [0.9505 1.0 1.0890]
>>>> 
>>           ] setcolorspace } def
>>  /setrgb { srgb setcolor } def
>> 
>> 
>> Then [A] volc2.10.eps (the fast one) uses commands like:
>> 
>>  /bg { 1 0 0 rgb } def
>> 
>> while [B] volc2.13.eps (the slow one) uses commands like:
>> 
>>  /bg { 1 0 0 setrgb } def
>> 
>> in each case for exactly the same purpose. Thus [B] the
>> slow one uses repeatedly (1157 times) a function setrgb
>> which has much higher overheads (see definition above)
>> than the function rgb used (1156 times) by [A] the fast one.
>> 
>> So the difference in performance is *definitely* down to
>> a specific difference in how R-2.13 implements 'postscript()'
>> compared with R-2.10.
>> 
>> Hoping this is useful!
>> Ted.
>> 
>> --------------------------------------------------------------------
>> E-Mail: (Ted Harding) <ted.harding at wlandres.net>
>> Fax-to-email: +44 (0)870 094 0861
>> Date: 21-Jul-11                                       Time: 16:26:33
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>> 
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> 
> -- 
> Peter Dalgaard
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com
> 

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Date: 21-Jul-11                                       Time: 21:13:21
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