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Pitstop 2017

Started by Tracy, July 05, 2017, 10:02:25 AM

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Tracy

In Action lists/ Device links / TAC Reduction:

I tried this out to reduce Ink and it seems to work really good
I haven't tested it out for weird color changes, but It's looking
like a better way to reduce ink coverage than the way I've been doing it with photoshop.

abc

That's the plan....
Which Action List did you use?

abc

Also remember it only works with DeviceCMYK

Tracy

I used the Gracol 280
I did see that it only works with Device CMYK
I will have to be mindful of that when I start using it.

I'm happy to see this!!!!

swampymarsh

Yeah, one has to dupe the default action lists and add steps to remove CMYK ICC from strokes, fills and other objects – or run an action list to do the same before running the default action list.

abc

Indeed, you can add a Select all > remove icc tags if you wish.
Another thing to remember is that if you use an Output Intent you should consider if that needs to be updated as well.

We did consider adding that to the Action List, but we know a lot of people don't use output intents, and we figured the ones that do would know enough that they could do it themselves.

Tracy

I'm curious how it actually works
I don't know anything about device links

swampymarsh

#7
Quote from: Tracy on July 07, 2017, 08:03:03 AMI'm curious how it actually works
I don't know anything about device links

Hi Tracy, I'll "try" to keep this simple with a CMYK output profile and attempt to skip over heaps of other stuff...

Standard Device profiles can have different colour tables (Perceptual, Relative Colorimetric, Absolute Colorimetric, Saturation). Then there is a "Profile Connection Space" or PCS which is a device independent (Lab or XYZ colour space) "translator". When you convert from say CMYK to CMYK a rendering intent, BPC and other options may be chosen. The source CMYK value is translated to the device independent PCS value, then the PCS to destination device CMYK value is used to remap the source. This is just a translation, the actual file is not actually converted to Lab colour space. So:

CMYK (source) > PCS > CMYK (destination)

DeviceLink profiles are simpler. There is no PCS. So there is no translation through an intermediate "abstract" colour space. There is no selection of rendering intent. All of the conversion options are "pre-baked" into the link profile. So:

CMYK (source) > CMYK (destination)

This allows a simple remapping of say 100% K (source) to 100% K (destination).

Going through a PCS "middleman" the conversion to destination would result in a rich black using CMYK values. The density of the converted black would be the same as the source, however it would not be K only. With a DeviceLink profile, 100K is used in a simple colour lookup table and 100K is the destination (if so desired).

It is common for DeviceLink profiles to maintain single primary solid values (i.e. 100% cyan etc.), secondary solid values (i.e. 100% cyan + 100% magenta etc.). Depending on the link generation software, other variables may be offered as well – such as the ability to zero out the white point values to remove paper white simulation with an absolute colorimetric intent transform. Sometimes vectors may be handled differently to rasters (however I don't like this option and prefer both to use the same).

DeviceLink profiles from commercial profiling packages are usually costly to purchase and have license restrictions around them (they are considered licensed software), so the Enfocus DeviceLinks are encrypted and can only be used in PitStop.

The key things to remember is that the chosen DeviceLink must represent BOTH the source and the destination. So if you are using an ISO Coated v2 link that drops the weight from 320% to 300%, then make sure that the source file is actually ISO Coated v2 as this will be the assumed source. Unlike standard device profiles, the source and destination are presumed and pre-built into the link, they are not referenced by the source ICC profile – which is why the source can't be ICC tagged and should be Device CMYK. Additionally, the result is "untagged" or Device CMYK, one can't tag/embed a link, so the destination ICC or Output Intent would need to be manually set.

swampymarsh

#8
Quote from: abc on July 07, 2017, 07:01:34 AMIndeed, you can add a Select all > remove icc tags if you wish.

Hi ABC, however I would beware of globally stripping out ALL profiles, as the RGB profiles are very useful and it is only the CMYK profiles that need to be removed if running a CMYK > CMYK devicelink (unless I am wrong, the devicelink conversion would not work on an object with an object level ICC profile).


abc

Very true, you can of course be very selective when removing tags based on the selections you use in the Action List.

abc

Also just to mention that the Reduce devicelinks have the same source and destination profile.

Tracy

Thanks for the info!!
Now I have lots of questions :laugh:

Why is removing RGB profiles bad
and what is object level ICC?

I think I need to get this.
Thanks!

abc

HI Tracy
Well if an object (normally images) have an icc profile attached, then you know how it was created ie which profile was used to capture it etc. So when you convert it to CMYK for example that profile is used as the source.
If you don't have a profile attached then you have to guess. Depending on the customer the differences between sRGB and Adobe RGB for example can make a difference.
Object level icc is the same thing, the object is tagged with an ICC profile.

Tracy

Thanks ABC that's making some sense.
You are in the perfect job, your a great teacher!

mattbeals

Quote from: Tracy on July 10, 2017, 12:06:56 PMThanks for the info!!
Now I have lots of questions :laugh:

Why is removing RGB profiles bad
and what is object level ICC?

I think I need to get this.
Thanks!

In order to get where you want to go you first need to know where it is you are starting from. The source RGB profile tells you exactly where you are coming from, your destination profile tells you where you want to end up. The color management engine (Google Maps) tell you the directions. A device link profile is essentially an optimized path without needing to ask the mapping engine (CMS) how to get there.

Or, if you're into Stargate you need the dialing computer (DHD/color management engine), the six coordinates for the destination planet/gate and the 7th point ( source location/source profile ). Can't dial without the point of origin.

Geeky enough?
Matt Beals

Everything I say is my own personal opinion and has nothing to do with my employer or their views.