Grayscale profile – Black Ink GRACoL2006_Coated1v2

[walterz]

Can someone please make available a GOOD grayscale profile that reflects the TVI of GRACoL2006_Coated1v2?

By “good” I mean it should meet the following criteria:
1. The same TVI as the black channel of GRACoL2006_Coated1v2. (Not simply Photoshop’s “20% Dot Gain”.)
2. When selected in Photoshop – Proof Setup (Custom Proof Condition) – it should allow to Simulate Black Ink.
3. It should allow you to delete to zero. By this I mean, when you select an area and you fill it with a background colour of pure white the resulting value is truly zero and not 1%. Or, if you convert an image that has a pure white area to this profile that the 0% area stays truly zero.

[mglouis]

Walterz,

Your subject line implies you know how to go into Photoshop's color settings and load a Gracol profile into the 'gray working space' dialogue. If not then give it a try. Select "load gray" and then select a 4cp printer profile and the black ink channel will be extracted and wrapped into a gray profile wrapper. It soft proofs. Not sure about #3. I find photoshop is good with preserving paper but the same profiles in other apps may cause 03.~0.4 unwanted tints. If this is not the case then ensure you do not have your color settings default rendering tint set to absolute colorimetric.

Matt Louis

[walterz]

Yes Matt, as you expected, I am familiar with the Photoshop feature that allows one to make a grayscale profile from a given CMYK profile. However, what I find is that #3 does not work as I expect. Regardless of what my default rendering intent is set to, Photoshop will always leave me with 1% grey.

The only exceptions I have found so far are: if I use a table-based profile (like 20% Dot Gain or my own custom made dot-gain based "profile"), if I select Apple CMM, or if I define the colour palette white by using the eye-dropper and selecting a zero white area in my Black Ink GRACoL image.

So, as you will likely suggest, I could use one of these methods to work around the problem. However, the intent is for this profile to be what we recommend our file creators use. If we recommend this profile with its flaws and there ends up being a minimum of 1% printing, we will be held accountable. We also cannot expect to educate everyone that might use this profile of its pitfalls and workarounds required.

[mglouis]

Walterz,

For what it is worth I am not able to replicate your problem. In Photoshop CS5 running ACE engine I can go round trip from Gracol to "black ink Gracol" a few times without a 1% dot. I can fill or delete with white or a white foreground or white background and still no 1%.

Matt Louis

[Lukas Engqvist]

Do you have a different CMYK profile than the one you are using to get the grey? It is most natural IMO to use the same CMYK as the cmyK you use for grey. (Are you using other than Relative rendering intent and BCP enabled? )

[meddington]

I'm getting the same situation as the OP. When creating a gradient from 0% - 100% for example, with the ACE CMM in CS4, I get a 1% dot in the highlight. Change to the Apple CMM and its 0%.

[walterz]

Thanks gentlemen for your replies.

Lukas – in general I hear you asking “have you tried…” Trial-and-error testing is the only thing I am able to do. I am unable to look “under the hood” of this profile. (to borrow Steve Upton’s terminology)

Meddington – Do you think this is a bug in the generating of the gray profile? If so, are there other software packages that can generate a Gray Profile from a CMYK profile?

This issue most often surfaces when our image editors are working on silhouette images and they want to delete specs from the white background. They select the area and hit <Delete> (which in the new Photoshop versions is a fill). The problem is that by doing so they introduce a 1% tint when their Gray Working-space is Black Ink – GRACoL2006_Coated1v2.

[rich apollo]

Hmm. Good catch.

Near as I can figure, the Adobe CMM is looking for the kTRC tag, which is missing from the GRACoL profile and (strangely enough) the Adobe profiles for the same data.

I've attached a grayscale profile that I built from the GRACoL data set. It seems to function normally. Test it and see.

[meddington]

I show , via ColorSync Utility. that there is a kTRC tag present, but oddly enough it doesn't bottom out to "0". See attached compared to a Gamma 2.2 profile.

[TerryWyse]

Wow...weird....if I create a new grayscale document with a white background, all is good (0%K). If I select an area and fill with white, still good. If I select an area and hit <delete>, I'm left with 1%K....tried this in both 8 and 16bit...same thing.

.....minutes later.....

It's an issue with the standard IDEAlliance GRACoL2006_Coated1v2 profile.......if I use a GRACoL profile built using either ProfileMaker5 or i1Profiler, it doesn't happen....doesn't happen with the "Coated GRACoL 2006..." profile that Adobe ships with CS4/CS5 either.

Terry