presentation: option screen or prepress in ps2pdf?

Question

I'm using the Powerdot class to make a presentation. Powerdot uses eps pictures and thus on compiling, I'm using the normal route:

Latex > dvi > ps > pdf. 

In Ghostscript, we have the ps2pdf tool. I normally use

-dPDFSETTINGS=/prepress

for all usage. I read somewhere that setting the /screen option instead of /prepress creates a smaller pdf file. For the presentation that I'm working on, I see that both settings give the same file size.

In any case, what's the best option to put for a presentation?

Am I right to think that setting the option to /prepress will create a file of high resolution that will make the presentation appear very well on a projector?

Answer 1

You can find all options of ps2pdf here. The PDFsettings part is below:

-dPDFSETTINGS=configuration
    Presets the "distiller parameters" to one of four predefined settings:

        * /screen selects low-resolution output similar to the Acrobat Distiller "Screen Optimized" setting.
        * /ebook selects medium-resolution output similar to the Acrobat Distiller "eBook" setting.
        * /printer selects output similar to the Acrobat Distiller "Print Optimized" setting.
        * /prepress selects output similar to Acrobat Distiller "Prepress Optimized" setting.
        * /default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file. 

So in principle /screen will give the smallest output. It's already enough for a projector.

Answer 2

I believe the following is true:

  -dPDFSETTINGS=/screen   -- 72 dpi;

  -dPDFSETTINGS=/ebook    -- 150 dpi;

  -dPDFSETTINGS=/printer  -- 300 dpi greyscale;

  -dPDFSETTINGS=/prepress -- 300 dpi color.

Correct me if I am wrong.