Re: OBA's yet again
Re: OBA's yet again
- Subject: Re: OBA's yet again
- From: Terence Wyse <email@hidden>
- Date: Wed, 17 Jun 2015 14:28:58 -0400
I would probably use delta L* and delta Chroma as a metric for grouping. Since we know when dealing with OBAs, your delta chroma is going to increase from near-neutral to blue in hue (yellow papers would throw a wrench in this).In my experience, you’re going to see increasingly positive a* and increasingly negative b* values as OBAs increase.
To keep it manageable, I would say deltas of 3 on L* and chroma for groupings would be reasonable.
Terry
> On Jun 17, 2015, at 1:06 PM, Mike Stewart <email@hidden> wrote:
>
> As I've mentioned before. we are a pre-press provider for publishers and
> printers worldwide. We use an Indigo Press as a proofer and 95% of the time
> print/proof is on the actual press stock. This paper is mostly supplied to
> us by the printer themselves. As I look into our press room I would say
> that I probably have about 150 different papers; three quarters of which
> are uncoated stocks heavily laden with OBA's. Using the i1Pro2 in M1 mode I
> have measured all the papers.
>
> I cannot possibly have 150 different colour managed Hot Folders with
> individual colour tables based on each stock we proof on. (It would be a
> nightmare to build and control). I want to group papers into groups based
> on LAB M1 measurements. Example: 94, 1.0, -9 might be one group. My colour
> managed Hot Folder would have a colour set up created from 94, 1.0, -9 and
> I'm wondering if there are any "rule of thumb" tolerances I could use for
> my groups. Say Group 1 has been set up with 94, 1.0, -9 and my tolerance is
> L+/- 2, *a +/- 1, *b+/- 2. I could now group all papers that fall within
> those specs. I realize colour would not be an exact match for each sheet;
> but should be close enough to allow a printer to "match" the proof.
>
> Has anyone done this and does anyone know if my tolerances are out of
> whack? My +/- 2 could become quite a large tolerance if ..
>
> 94, 1.0, -9
> 92, -1.0 -7 Is this to large of a gap?
>
> Any help would be appreciated.
> Mike Stewart
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