I can try to address the 2400 dpi printer resolution.
Printer manufactures specify their printer's resolution in the number of pixels
per inch (ppi) in the horizontal plane because it’s higher, and looks better in
advertising. But all printers also have a vertical printing resolution that is
much lower, and therefore is the true limit on the resolution that a printer
can print high quality images.
Printed magazines are screened at 133 lines per inch in the vertical dimension
and so twice that resolution is all you need in ppi to get the best possible
print. Magazines typically print at 2400 dpi in the horizontal plane. 266 dpi
is all you’d really need, but people generally use 300 dpi because they don’t
understand how offset printing presses work. Coffee table books (high end)
print at 200 lines per inch.
Poster printers, which can print extremely high resolution in the horizontal
plane generally only need 180 dpi in files because of the lower resolution in
the vertical plane. And the fact that throwing a huge 2400 dpi file at a poster
printer will generally slow it’s print speed to a crawl… and that make printing
multiple posters in a limited amount of time hard to do.
All printers are pretty similar but you should check yours for it’s specific
details. All printers have multiple settings and options that will effect print
speed and quality but check yours for the lpi (lines per inch) and then double
that number to figure out how much dpi you need.
Most people do not understand how this all works, I can try and give a primer
on it. Using the information above as the example, if you want to have a final
image size of four inches in a magazine, then you’d need to ray trace your file
at 4" x 300 dpi = 1200 dpi in width.
So once you figure out the size of the image you want the final image to be,
multiple that by twice your printer's vertical printing limitation, to get the
ray trace image width.
> On May 9, 2016, at 7:34 PM, Stephen Kerry <stephen.kerr...@outlook.com> wrote:
>
> Thank you for trying this out on a workstation with 128 GB and then 256 GB of
> RAM. It is much appreciated as I do not have easy access to that kind of
> computational power. The fact that you also get these segfaults with all of
> your RAM, suggests that this might be a PyMOL limitation, rather than a
> hardware issue.
>
> I have come to the conclusion that it is impossible to ray trace an image
> with an output resolution greater than 45 megapixels (7500 x 6000). Halving
> the dpi from 1200 to 600 gives a 11.25 megapixel (3750 x 3000) resolution.
>
> I was wondering if the developers have come across this upper limit too? I
> have a 2400 dpi printer, so I want to go with the highest dpi possible for
> the best quality.
> From: David Hall <li...@cowsandmilk.net <mailto:li...@cowsandmilk.net>>
> Sent: 06 May 2016 19:17:38
> To: Stephen Kerry
> Cc: pymol-users@lists.sourceforge.net
> <mailto:pymol-users@lists.sourceforge.net>
> Subject: Re: [PyMOL] High Resolution Ray Tracing
>
> Feel free to send me the files off list.
>
> -David Hall
>
>> On May 6, 2016, at 1:54 PM, Stephen Kerry <stephen.kerr...@outlook.com
>> <mailto:stephen.kerr...@outlook.com>> wrote:
>>
>> Dear All,
>>
>> I have a protein complex scene that I need to create a large, high
>> resolution (1200 dpi) ray traced image of, but am unable to do so as I
>> always run out of memory at the end of the ray tracing process, with the
>> following error:
>>
>> python2.7(972,0x7fff7397f300) malloc: ***
>> mach_vm_map(size=18446744068907188224) failed (error code=3)
>> *** error: can't allocate region
>> *** set a breakpoint in malloc_error_break to debug
>>
>> This is with PyMOL 1.81 from Fink on OSX 10.10 with an i7-4790K processor
>> and 32 GB of DDR3. Python2.7 expands up to 15 GB of RAM, with more than
>> twice this reserved for virtual memory, but no swap is actually used.
>>
>> Decreasing hash_max just increases the ray tracing time until the error at
>> the end. Sometimes PyMOL will be terminated with this error, whilst at other
>> times a transparent PNG is all that is produced.
>>
>> Is there a way to force PyMOL to use virtual memory to avoid these
>> errors/crashes at the expense of processing time?
>>
>> If not, is there anyone who has PyMOL 1.8x installed on a system with 64 GB
>> or more RAM, who would be able to render this ray traced image if I send
>> the, the .pse file and .pml script off list? Takes about 10 mins to process.
>>
>> Cheers,
>>
>> Stephen
>>
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