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rogerB
11-05-2010, 09:04 PM
Assume a ColorSetup with a CMYK Reference as the PCO and three presses as the SCO. Assume the CMYK Reference is using SWOP3 as its ICC profile. Assume each presse represent a unique Device Condition, complete with its own characterization data, done on the same substrate, using the same line screen but having a unique identifier in the Other field, in order to differentiate each one to ColorFlow.

In the Conversion Definition for each presses, assume GrayBalance curves is selected along with a unique DeviceLink profile.

In Job Attributes, assume this ColorSetup is used.

In the Refine PT, I don't want any color conversion to take place, because I don't know ahead of time which one of the three press will actually be running the job.

To completely safeguard against the hazard of ICC profiles being present in the PDF, which we know will trigger a color conversion (through which DVL? or how?), it's possible to use the friendly "Override Embedded Profiles" check boxes, in the ColorConvert tab.

But, better than this approach, in my view, why not simply introduce a built-in ColorSetup type called "NONE" or "NullConversion"?, to be made available in the drwopdown menu, alongside the other defined ColorSetups?

That way, regardless of how the PDF was created in the first place, Quark, InDesign, what have you, with some Output Intent or embedded profiles being present at the image level, in the submitted PDF, Prinergy would never be able to make any kind of color conversion. That setting would UNEQUIVOCALLY turn it off assuring CMYK in = CMYK out.

I've been experimenting with the Refine of various PDFs lately and, unless I am adamant that there are absolutely nothing but DeviceCMYK or DeviceGray objects in the PDF, a color conversion does takes place *if* I fail to check the "Ignore Embedded Profiles" check boxes.

Now, which of the three SCO presses's various Device Link Profile will actually get called? I don't know. But a color conversion, nevertheles, occurs. In my mind, none of them should get called.

I do see the need to make absolutely crystal-clear to Prinergy exactly when to carry a conversion. Right now, I find the criterion too vague or plain non-existent. As soon as I define a DeviceLinkProfile in Conversion Definition, in a given Color Setup, there is no telling whether that DVL profile will get called during Refine or not? Again, if ICC profiles are present in the Refined PDF, a conversion will be triggered for sure -- with which DVL from the three presses, I don't know? But if there are no ICC profiles present in the PDF to begin with, then no conversion should take place, regardless of the state of "Override Embedded Profiles" check boxes.

Since ColorFlow is supposed to be a color management layer sitting on top of Prinergy, architecturally, why not square the Ts and dot the is with regards wot whether to leave to an undocumented criteria dictate the color conversion?

In my mind, we should not have to resort to checking off the 'Override Embedded Profiles' to safeguard against color conversion at Refine time! This is nuts and totally unintuitive, and probably not documented (I have not checked the only guide about this, to be frank).

Rather, ColorFlow should introduce a ColorSetup = NONE option, specifically designed to instruct Prinergy to turn all color conversions off. Period. That's a concept anyone can understand.

If RGB elements are expected in the PDF, that's another story...

Best / Roger

jstotz
12-06-2010, 06:16 PM
Roger, did you ever get an answer to this? In the ColorFlow user guide, the section on Color Inputs seems to imply, that if there is no Color Input that no conversion will be done during refine. However, it doesn't really state that explicitly.

rogerB
12-06-2010, 07:17 PM
Roger, did you ever get an answer to this? In the ColorFlow user guide, the section on Color Inputs seems to imply, that if there is no Color Input that no conversion will be done during refine. However, it doesn't really state that explicitly.

Jamie, nothing. I guess the point is either to use those two checkboxes, as a policy, or to make 100% sure that all clients never include profiles in the first place.

Best / Roger

david.herder
01-07-2011, 06:48 PM
Hi Roger,
My apologies, for some reason I missed this thread.

if ICC profiles are present in the Refined PDF, a conversion will be triggered for sure -- with which DVL from the three presses, I don't know

Yes and no. If you have an embedded ICC profile in the input file and choose not to override this profile, then you will be allowing a conversion. The conversion is Source=embedded profile, Destination=PCO ICC profile. If you override the embedded profile, and choose not to enable any source conversion (disable all 4 image/graphic ICC input fields), then no conversion will occur at all.

ColorFlow should introduce a ColorSetup = NONE option, specifically designed to instruct Prinergy to turn all color conversions off. Period. That's a concept anyone can understand.

The problem with this is that (at this point), saying that the introduction of a color setup called "None" allows for no color conversion would be a bit misleading. For example, if I have DeviceGray and CIELAB objects in the file, those are still going to be converted to whatever color response is defined by my PCO ICC profile. So, if we say that having a Color Setup = None produces no CMYK or RGB conversion would that be good enough even though other non-cmyk/rgb color spaces would convert ?


dave