4 Jul
2017
4 Jul
'17
8:01 a.m.
Hi Carl + Carsten.
Really sorry I've not come back on this yet. Have got sidetracked by
another project which is consuming all my time.
But thanks loads Carsten for all the detailed info. I intend to get back
on the case next week and will post on the list when I have got to the
bottom of it. My working assumption at present is that the post house
exported the TIFF image sequence with wrong white point.
Jim
On 03/07/2017 16:19, Carl Hetherington wrote:
Hi Jim,
Did you ever get to the bottom of this?
Kind regards,
Carl
On Fri, 16 Jun 2017, Jim Dummett via DCPomatic wrote:
> Thanks for your replies Carsten and Manuel. Answers to your Qs below
> Carsten.
>
>
> On 14/06/2017 11:18, Carsten Kurz wrote:
>> I can only assume that in fact the XYZ conversion is either done
>> wrongly, or, your personal reference system is out of balance. If in
>> doubt, there is no way other then going to a cinema with it (you can
>> render a small part to a USB stick) and check there
> I did this yesterday. On screen, the green cast was less pronounced than
> on my computer monitor, but I think was still present. Certainly the
> images had a dull subdued look to them. I also made a DCP in DOM from a
> Rec709 Quicktime reference file and that looked much more punchy. The
> director came to the screen test and said the DCP made from the Rec709
> was more what he'd aimed for in the grade.
>
> So, it looks like my monitoring at office is exaggerating the problems,
> but that it still persists in the cinema.
>
>> Is that TIFF you linked to in your first email the ‚incoming' TIFF from the
> posthouse, or has it been extracted from the DCP you created? You may supply
> one of the original TIFFs to us, so we can have a look. And if possible, the
> same, or close by, image from a ProRes/rec709 source.
>
> The TIFF is the incoming TIFF from the post house, which is supposedly
> XYZ colourspace. Here are the files:
>
> XYZ still: https://www.cinebox.co/clockxyz.tiff
> Rec709 still: https://www.cinebox.co/clockrec709.tiff (from Quicktime
> for comparison)
>
> Once converted to DCP, the centre of the clock appears off-white.
>
> I'm a bit at a loss how to trouble-shoot this now. I'd like to determine
> for sure that I'm not doing anything wrong and DCP-o-matic is doing the
> colour conversion (or, in this case, the lack of conversion!) correctly
> before I go back to the post house. Any idea of some other software I
> could try out making DCP from the XYZ sequence to compare to
> DCP-o-matic's output?
>
> Thanks again for all your help.
>
> Jim
>
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