On Wed, Jan 6, 2016 at 3:49 PM, Laurence Rochfort <laurence.rochf...@gmail.com> wrote: > 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? Darktable should be able to handle such big images, but it was not optimized in any way for _that_ big images, so there might be a still bugs. Be sure to use darktable-2.0 I personally have tried loading ~350MPix images last year, it worked, but slow.
> 3 * 4 * 1280 * 4 = 61440 -> 61 GB RAM? Yes, i think math is correct here... > Will it really need that much or will the tlinig you talk about reduce that? Well, no, that is the lower estimate, you can not* go below that number. (* in darktable, because all the operations are working on 4-channel floating point data, and tiling is per-module, so we need to always have full-sized input buffer and full-sized output buffer + some internal memory for processing) (the alternative is per-pipe tiling, but it is not possible in darktable. but you can "emulate" it by splitting** that input 1.2 Gigapixels image into smaller pieces, processing them separately, and then joining** them. ** outside of darktable) > 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? I *think*, CPU <-> RAM connection will be the hotspot. Be sure to let us know if it works :) > 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 ------------------------------------------------------------------------------ _______________________________________________ Darktable-users mailing list Darktable-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/darktable-users
