To calculate MPix from DPI use (length_in_inch*nr_dpi) * (width_in_inch * nr_dpi).
So for 4” * 5” film at 3000 dpi you get (4 * 3000) * (5 * 3000) = 180 MPix According to Roman’s rule of thumb, one image will need > 8 GB RAM. IMHO you don’t need to worry about CPU parallelism in that case, you should choose the slower CPU if you can avoid swapping that way. Cheers Michael Von: Laurence Rochfort [mailto:laurence.rochf...@gmail.com] Gesendet: Mittwoch, 6. Januar 2016 12:47 An: Roman Lebedev Cc: darktable-users@lists.sourceforge.net Betreff: Re: [Darktable-users] Benefit of more than 4 cores vs "speed" I have no idea how many MPix. I've only ever used film, so I don't think of it in those terms. How can I calculate MPix from DPI? Any thoughts on CPU parallelism vs speed? Cheers, Laurence. On Wed, Jan 6, 2016 at 11:32 AM Roman Lebedev <lebedev...@gmail.com> wrote: On Wed, Jan 6, 2016 at 2:19 PM, Laurence Rochfort <laurence.rochf...@gmail.com> wrote: > Hello all, Hi. > > I'm building a new PC with scrounged components. I have the option of either > a dual Xeon E5645 with up to 96GB RAM, or an i5-3470 with 8GB RAM. > > The storage is a PCIe x4 SSD. > > You can see a comparison here: > http://cpuboss.com/cpus/Intel-Xeon-E5645-vs-Intel-Core-i5-3470 > > I'll mostly be dealing with medium format and 4x5 drum scans, so TIFF files > that are from 200MB to 1GB. Mostly I'll be doing crop, rotation, colour and > zone adjustment. Yes, but how much MPix? 50 MPix? 100 MPix? (very rough rule of thumb, lower estimate: for x pixel image, you want at least 3 * 4 * x * 4 bytes memory; that is, for 20MPix = 960 MB) If more than ~50MPix, then you *absolutely* need as much RAM as you can get. I doubt that GPU would be of any help at those sizes though... > > Could people advise me on which would perform best? > > Many thanks, > Laurence. Roman. > > ------------------------------------------------------------------------------ > > _______________________________________________ > Darktable-users mailing list > Darktable-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/darktable-users >
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