On Wed, 24-Nov-2004 at 10:22AM -0600, Marc Schwartz wrote: |> On Wed, 2004-11-24 at 16:34 +0100, Witold Eryk Wolski wrote: |> > Hi, |> > |> > I want to draw a scatter plot with 1M and more points and save it as pdf. |> > This makes the pdf file large. |> > So i tried to save the file first as png and than convert it to pdf. |> > This looks OK if printed but if viewed e.g. with acrobat as document |> > figure the quality is bad. |> > |> > Anyone knows a way to reduce the size but keep the quality? |> |> Hi Eryk! |> |> Part of the problem is that in a pdf file, the vector based instructions |> will need to be defined for each of your 10 ^ 6 points in order to draw |> them. |> |> When trying to create a simple example: |> |> pdf() |> plot(rnorm(1000000), rnorm(1000000)) |> dev.off() |> |> The pdf file is 55 Mb in size. |> |> One immediate thought was to try a ps file and using the above plot, the |> ps file was "only" 23 Mb in size. So note that ps can be more efficient. |> |> Going to a bitmap might result in a much smaller file, but as you note, |> the quality does degrade as compared to a vector based image. |> |> I tried the above to a png, then converted to a pdf (using 'convert') |> and as expected, the image both viewed and printed was "pixelated", |> since the pdf instructions are presumably drawing pixels and not vector |> based objects.
Using bitmap( ... , res = 300), I get a bitmap file of 56 Kb. It's rather slow, most of the time being taken up using gs which is converting the vector image I suspect. Time would be much shorter if, say a circle of diameter of 4 is left unplotted in the middle and others have mentioned other ways of reducing redundant points. A pdf file slightly larger than the png file can be made directly from OpenOffice that has the png imported into it. For a plot of 160mm square, this pdf printed unpixelated. Depending on what size (dimensions) you need to finish up with, you might find you could get away with a lower resolution than 300 dpi, but I usually find 200 too ragged. HTH -- Patrick Connolly HortResearch Mt Albert Auckland New Zealand Ph: +64-9 815 4200 x 7188 ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~ I have the world`s largest collection of seashells. I keep it on all the beaches of the world ... Perhaps you`ve seen it. ---Steven Wright ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~ ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html