PANTONE with "limited gamut" on RGB documents. Why?

[Dreatern]

As you can see in the image below, the PANTONE palette appears to be presented in RGB with a limited gamut range, something that would and is expected in CMYK.

In CMYK, PANTONE colors are basically the same in any color profile.  But for some reason the same colors in RGB have a shift
Is that intentional? a bug?  Can't RGB display almost the entire CMYK gamut?
 

[lacerto]

22 hours ago, Dreatern said:

Can't RGB display almost the entire CMYK gamut?

It seems that Affinity apps basically define PANTONE colors in terms of sRGB (rather than in Lab color space). This means that their visual appearance is limited to sRGB even when the document color space allows a larger gamut, like e.g. when using ROMM RGB, as below (note that the forum narrows the color space of any screenshot to sRGB, but the difference shows relatively):

Note that InDesign, on the right, shows the PANTONE colors in Lab color space no matter what. Above the InDesign document has sRGB and ISO Newspaper assigned as RGB and CMYK color profiles but the PANTONE colors are shown purely, in terms of Lab color space, and realistically as long as the display color gamut allows it.

However, within Affinity apps, when the document is in CMYK color mode, the sRGB based PANTONE colors are shown simulated (as a kind of a proof print) using the active document CMYK profile, below ISO Coated V2:

This is of course inaccurate and highly misleading, but basically expected whenever a color definition is made in terms of (s)RGB, not considering the spot colors as specific inks but rather as part of the process color space.

 

[Dreatern]

I got it. Thanks for the answer 

[User_783649]

@lacerto Great finding! You're absolutely correct. Seems like all Pantone values in Affinity apps are "hard-coded" to sRGB color space. Which is totally wrong in my opinion. I take a look at Contents/Resources/Pantones folder of my macOS Affinity Publisher. There are .CSV files with all Pantones listed.

[lacerto]

I had another (and proper) look on the issue, and this is actually another thing, and something I really do not get.

PANTONE+ CMYK is basically a library that specifies CMYK values for coated and uncoated stock to get output that matches PANTONE defined CMYK printouts.

The values that one gets when exporting colors defined by using this color library match exactly what is defined by PANTONE e.g. in PANTONE Color Manager for sRGB values, and exactly the same that InDesign shows as CMYK values of these library swatches. So Affinity apps and Adobe apps seem to give identical CMYK output when using this PANTONE color library (the color definitions of the U library are intended to be used with uncoated stock using profiles like U.S. Web Uncoated V2 or Uncoated Fogra 29). 

But what is interesting is that the official sRGB values that PANTONE Color Manager specifies, and which Affinity apps use, differ significantly from the CMYK output, exactly as noted by @Dreatern, as if the sRGB gamut could not produce the defined CMYK colors for uncoated stock, which is simply just absurd! It is true that there are colors in the region of cyan that cannot be reproduced in sRGB, but the ones shown in the blue region in this library are not such, and interestingly InDesign completely discards the PANTONE guide values when it produces an sRGB output of these colors and uses standard profile conversion between any given CMYK to RGB color space, and gets a much closer match.

a) Same PANTONE CMYK Uncoated definitions in sRGB (left) and CMYK US Web Uncoated V2 color modes (right). The document color palette shows the RGB guide values of the PANTONE library that will be used in sRGB export, and the actual CMYK values used for CMYK output. The actual sRGB conversion values for the CMYK colors do not match the guide values, which give oddly desatured RGB output: 

b) The same PANTONE library used in InDesign, and the Swatches palette showing first the library defined CMYK swatch (with identical CMYK values produced by Affinity Publisher), and then smaller swatches with RGB values used by InDesign, and guide values given by PANTONE. 

Here are CMYK and sRGB PDFs produced by both apps for comparison. It can be seen that InDesign, which discards the PANTONE defined sRGB values, produces more accurate RGB output from this library.

 PMS_CMYK_Uncoated_cmyk_apub.pdf

PMS_CMYK_Uncoated_srgb_apub.pdf

PMS_CMYK_Uncoated_cmyk_id.pdf

PMS_CMYK_Uncoated_srgb_id.pdf

I must have misunderstood something here, but feel kind of relieved not to be dependent on anything like PANTONE libraries to be able to produce CMYK colors reliably and getting closely matching sRGB output for digital versions of the publication!

[Dreatern]

@lacerto Thanks for the additional info.
@Alex M Can the issue be fixed by editing that CVS with correct values? a work around

[lacerto]

4 hours ago, Dreatern said:

Can the issue be fixed by editing that CVS with correct values? a work around

I think you could if you have Affinity Store purchased versions, but I am not sure if you could edit CSV files that are stored sandboxed when using Microsoft or Apple Store purchased versions.

[bteifeld]

The most reliable representation of any color in a named color/spot color system is its device independent L*a*b* value. Using an ASE file export from Pantone Color Manager, you can replace any fan deck included in the affinity applications with the L*a*b* representation. It might also ensure that you get a timely update of the pantone color of the year from the Cotton TCX deck if you need that.

[camelia]

I can not find the PANTONE palette for silk screen printing

Help 😭

Came

[lacerto]

10 hours ago, bteifeld said:

The most reliable representation of any color in a named color/spot color system is its device independent L*a*b* value. Using an ASE file export from Pantone Color Manager, you can replace any fan deck included in the affinity applications with the L*a*b* representation. It might also ensure that you get a timely update of the pantone color of the year from the Cotton TCX deck if you need that.

.ASE imports from PCM can have Lab color values but I have not been able to have them displayed realistically within Affinity apps unless I use an RGB document mode with a color profile with large enough gamut to display off-sRGB PANTONE colors, which then would require native RGB color definitions within the same color profile (and not e.g. in sRGB). When using sRGB (not to mention CMYK color modes), muted colors are shown, which makes Lab-based definitions less useful in Affinity environment; the colors would show muted also in PDF exports, making simulation of spot colors inaccurate. But at least the PANTONE defined Lab color values can be seen in the user interface.

Another problem with spot color ASE imports is that this seems to be currently possible only on macOS (further exporting in .afpalette format would allow transferring spot color palettes also onto Windows). This "bug" is actually useful as it kind of allows the user to decide whether swatches are imported as spot colors or by using the underlying color definitions (RGB/CMYK/Lab).