Re: GCR Problem
Re: GCR Problem
- Subject: Re: GCR Problem
- From: Steve Miller <email@hidden>
- Date: Mon, 02 Feb 2009 13:16:28 -0600
- Thread-topic: GCR Problem
Jon,
I just tried those %'s through our Alwan CMYK optimizer server. Alwan didn't
change the K% at all.
Since you said you are not converting profiles you are just using it for GCR
conversions, I set the profiles to be the same input and output profile.
Used the dynamic maximum black with K starting at 11%.
I had the following options checked in the purity tab.
C-m-y
Cm-my-yc
Ck-mk-yk
K primaries
100% solids primaries
200% solid secondaries
200% solid ck-mk-yk
If you'd like to email me your file I could process it through our server to
see what's happening.
Steve
On 2/2/09 12:54 PM, "Terence Wyse" <email@hidden> wrote:
> You're looking for logic that says...
>
> If current K is >= GCR logic results: leave K unchanged.
> If current K is < GCR logic results: convert.
>
> Not sure how to do that with CMYK Optimizer or other products but it
> does seem "simple" though.
>
> Terry
>
>
>
> On Feb 2, 2009, at 1:42 PM, Jon Crook wrote:
>
>> Ok, I lowered my K-start to 10% and that did not make a difference
>> on the
>> build we are discussing; however it did lessen the amount of black
>> that is
>> taken out of the other photographs in this project.
>> This seems to be over-engineered for what Im trying to do with it. I
>> am not
>> using this particular workflow for profile conversions, Im just
>> using it for
>> GCR conversions. Is there a better way to do this?
>>
>> Seems to me that if some kind of software would just go through an
>> image
>> pixel by pixel and apply GCR to a certain E off of neutral then
>> this would
>> accomplish what I am after.........I think.
>>
>> I know what I am after but Im not sure of the best way to get there.
>>
>>
>> On 2/2/09 11:29 AM, "Steve Miller" <email@hidden> wrote:
>>
>>>
>>> Jon,
>>> Your original separations have 11% K in them. You moved your K-
>>> start to 15%.
>>> This could be the reason you are still not getting the amount of
>>> black you
>>> want.
>>> Move you K-start to 10% and let us know what happens.
>>>
>>> Regards,
>>> Steve
>>>
>>> On 2/2/09 11:24 AM, "Jon Crook" <email@hidden> wrote:
>>>
>>>> I threw colorimetric accuracy out the window and lowered my K-
>>>> start to 15%
>>>> and switched on CK-MK-YK ink purities and it was still pulling
>>>> from the K
>>>> sep and adding to the CMY sep. It wasn't as bad but still present.
>>>> There has
>>>> got to be a way to do these separations reliably.
>>>>
>>>>
>>>> On 2/2/09 10:51 AM, "Terence Wyse" <email@hidden> wrote:
>>>>
>>>>> Hi Jon,
>>>>>
>>>>> If you're using CMYK Optimizer and the "dynamic" GCR option, the
>>>>> resulting conversion can be somewhat unpredictable. It's based on a
>>>>> lot of factors including the actual pixel area in the image.
>>>>> While not
>>>>> exactly your issue, the program will tolerate a certain amount of
>>>>> excessive total ink coverage depending on the actual pixel area
>>>>> that
>>>>> it's sampling and how large it is.
>>>>>
>>>>> In your case, it might be as simple as the where you have the K
>>>>> start
>>>>> point set in the GCR setting. If your K start point is, say, 25%,
>>>>> then
>>>>> what you're seeing would be expected where it would actually
>>>>> REMOVE K
>>>>> and convert back to CMY. Only solution would be to start the K as
>>>>> early as you can tolerate.
>>>>>
>>>>> There's another way to prevent this from happening that may be the
>>>>> best option. In CMYK Optimizer you should have control over the
>>>>> primary
>>>>> +K combinations (CK, MK and YK). By checking this option on, it
>>>>> should
>>>>> prevent what you saw happen. You can do the same for secondary+K
>>>>> combinations as well (CMK, CYK, MYK).
>>>>>
>>>>> Regards,
>>>>> Terry Wyse
>>>>>
>>>>>
>>>>>
>>>>> On Feb 2, 2009, at 11:25 AM, Jon Crook wrote:
>>>>>
>>>>>> I need help understanding what is going on behind the scenes in
>>>>>> Alwan CMYK
>>>>>> Optimizer. I have it set to apply a certain level of GCR and works
>>>>>> beautifully most of the time but once in a shile I get an image
>>>>>> that
>>>>>> seems
>>>>>> to separate the exact opposite to the way that I intend.
>>>>>> Here is an example:
>>>>>> Original build is C=0 M=0 Y=27 K=11
>>>>>> New build through Alwan C=11 M=4 Y=36 K=0
>>>>>> Correct me if Im wrong but isnt this conversion the exact opposite
>>>>>> of what
>>>>>> GCR should be? Since there was not any Cyan or Magenta in the
>>>>>> original
>>>>>> build, I would think that there would be no conversion at all. Im
>>>>>> sure Alwan
>>>>>> applies GCR the same way as other ink optimizing programs. Can
>>>>>> anyone tell
>>>>>> me exactly what is going on behind the scenes so I can better
>>>>>> understand
>>>>>> this process.
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> --
>>>>>> Jonathan Crook
>>>>>> Director of Color Management
>>>>>> Corporate Image
>>>>>> www.corp-image.com
>>>>>> 800.247.8194
>>>>>>
>>>>>> _______________________________________________
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>>>>>
>>>>> ______________________________
>>>>> Terence Wyse, WyseConsul
>>>>> Color Management Consulting
>>>>> G7 Certified Expert
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Do not post admin requests to the list. They will be ignored.
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>>>>>
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>>
>> --
>> Jonathan Crook
>> Director of Color Management
>> Corporate Image
>> www.corp-image.com
>> 800.247.8194
>>
>> _______________________________________________
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>
> ______________________________
> Terence Wyse, WyseConsul
> Color Management Consulting
> G7 Certified Expert
>
>
>
> _______________________________________________
> Do not post admin requests to the list. They will be ignored.
> Colorsync-users mailing list (email@hidden)
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> This email sent to email@hidden
--
Steve Miller
Norwood Publishing
1000 Highway 4 South
Sleepy Eye, MN 56085
507-794-8203
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