Thanks all for the response. I'm getting some pretty huge numbers for a 4x5 at 8000DPI using your formulas above.
(4 * 8000) * (5 * 8000) = 1280000000 -> 1.2 Gigapixels? 3 * 4 * 1280 * 4 = 61440 -> 61 GB RAM? Will it really need that much or will the tlinig you talk about reduce that? Fortunately, I have access to 144GB of RAM so it doesn't really matter, but just curious. Can I conclude that I'm unlikely to be CPU bound with a single 6 core/12 thread 2.4GHz Xeon? Thanks for all the advice! On Wed, Jan 6, 2016 at 12:20 PM Roman Lebedev <lebedev...@gmail.com> wrote: > On Wed, Jan 6, 2016 at 3:08 PM, Michael Below <be...@judiz.de> wrote: > > 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 > (yes, sounds about right) > > > According to Roman’s rule of thumb, one image will need > 8 GB RAM. > I should probably note that those 8Gb must not be the the total amount of > RAM in the system, but the amount of free ram, fully available for > darktable. > > And do note that it is the lower estimate, in many cases darktable will > need > *much* more. Though in many of those cases tiling will kick in and help. > > > 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 > Roman. > > > > > > > > > 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 > >> > > > > > > > ------------------------------------------------------------------------------ > > > > _______________________________________________ > > Darktable-users mailing list > > Darktable-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/darktable-users > > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Darktable-users mailing list > Darktable-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/darktable-users >
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