.....what if?

[tmiller_iluvprinting]

I received an email the other day from Pantone. Pantone now offers D50 Lighting Indicator Stickers that can be attached to a proof before it is sent out to the customer. Similar to GATF's RHEM Indicator, but produced with different metamers. These stickers are expensive, $50 USD for 40 stickers. My thought is this, is it possible to create a metameric pair that you could print on your Epson proof next to your qualifying target that would indicate that the proof is being viewed in D50 lighting? I really don't know how the D50 Lighting Indicators are created. Are they created with 2 spectrally different colorants? Or, is it possible to create 2 spectrally different colors using the same colorants that are a metameric match under D50? Any thoughts?
Best regards,
Todd

 

[Lukas Engqvist]

Should be possible.

 

[gordo]

[snip]My thought is this, is it possible to create a metameric pair that you could print on your Epson proof next to your qualifying target that would indicate that the proof is being viewed in D50 lighting? I really don't know how the D50 Lighting Indicators are created. Are they created with 2 spectrally different colorants? Or, is it possible to create 2 spectrally different colors using the same colorants that are a metameric match under D50? Any thoughts?
Best regards,
Todd

Yes they created with 2 spectrally different colorants? Therefore it is not possible to create 2 spectrally different colors using the same inks - like those in your Epson. You might be able to create a color on your Epson and then match it by printing an offset process blend on the proof itself to create a metameric match under D50. Or you could print one target spot color using two spectrally different base inks to create a metameric match under D50.

best, gordo

 

[tmiller_iluvprinting]

Thanks Lukas & Gordo,
You've given me a couple ideas.
Best regards,
Todd

 

[Deleted member 16349]

I received an email the other day from Pantone. Pantone now offers D50 Lighting Indicator Stickers that can be attached to a proof before it is sent out to the customer. Similar to GATF's RHEM Indicator, but produced with different metamers.
Todd

A metameric match by definition is one where the two targets do not have the same spectral curve but visually match under a specific lighting condition. Two targets that have the same spectral curve, would look the same but would not be a metameric match.


An interesting test to show that scanners and cameras, which use rgb sensors, can not capture colour is to scan the above Indicators and then view the results. You should be able to easily see the two different colorants used to make the Indicator.

Even if the camera or scanner used D50 light, there would be visible bands.

What does this mean? It means that even if some kind of profile is used on these devices, they are still not able to capture colour accurately.

Something to think about.

 

[rich apollo]

Todd, try printing alternating K-only and CMY stripes. That will be your best bet to do this on an Epson. You could do it on an offset press easily. I'm not sure about the color inconstancy of the Epson inks. Offset inks change dramatically under different lighting conditions.

 

[Lukas Engqvist]

If pure colours of the primaries can be plotted spectral reflectivity you should be able to see if there is a difference that can be used to your advantage. Perhaps as Rich is intending but there ought to be "more" combinations. I'm thinkning if you get some LAB colour bars… separate them with different GCR settings there should be visible which colors are most sensitive to shifts in lighting.

I'm thinking that there must be differences in Light Magenta + light cyan versus % of magenta and cyan giving same tint… or something like that (but not sure how much the individual inks can be controlled for that). Also may be a Green with Yellow+K vs green with C+M+Y… I'm suspecting we get more effect if we can get more inks mixing = more chemistry

 

[Stephen Marsh]

Many RIP manufacturers license commands from say Epson or other printer manufacturers, that allow them to drive the multiple separate and individual inkjet heads, such as when performing a calibration/linerization. However, when it comes to general printing, I was under the impression that all of the input data goes through the device profile PCS to the four colour device profile - and then the heads output whatever ink is required with no direct end user control over the primary ink and how much is used. Do some RIPs offer the ability to bypass the device profile and set an area of a file to only fire a certain head?

So how does the price compare between the Pantone and GATF labels?


Stephen Marsh

 

[tmiller_iluvprinting]

@ Rich- that's one of the problems, Epson inks are pretty stable under different light sources. I think you may be right about the k vs. cmy build. I'll give that a try.
@Stephen- the price of the stickers is comparable. You get a few more stickers when you purchase the RHEM Indicator, but the price is higher.
@Lukas- keep in mind this is something that I want to output on my proofs seamlessly.
Best regards,
Todd

 

[Stephen Marsh]

@ Rich- that's one of the problems, Epson inks are pretty stable under different light sources. I think you may be right about the k vs. cmy build. I'll give that a try.

Many inkjet device profiles use a high GCR so you would need to factor that in as it may be harder to get a K only vs. CMY build. That being said, some RIPs do have "preserve black" features that may at least keep the CMY out of the K.

Stephen Marsh

 

[Lukas Engqvist]

@tmiller I'm thinking there should be some way to append an unmanaged strip. The key to the whole thing is that you need a way to control colour other than ICC managed colour conversion… In Lab or RGB you only get one possible mix for a specific colour… it is first when you use 4 or more inks that you can get alternative recipes that will produce the same colour for a given viewing condition, (and in your case you want the colour that is VERY peculiar about just that the narrow band defining the viewing condition that will give multiple recipes a visible match).

What I am trying to be explicit about is you NEED to be able to bypass colour management and directly access ink builds. It may be something that is beyond what you are able to do but that RIP or inkjet manufacturers might be able to research and produce in future… and if they run with your idea, then I hope you get some cred

 

[Stephen Marsh]

Exactly Lukas, that is what I am saying! It is hard to beat or circumvent ICC colour management in proofing RIPs.

Stephen Marsh

 

[tmiller_iluvprinting]

Many thanks to all. Great ideas and suggestions, you've all given me plenty to think about!
Best regards,
Todd

 

[Deleted member 16349]

What I am trying to be explicit about is you NEED to be able to bypass colour management and directly access ink builds.

In my opinion, this is the way to go for the future. It would be a no brainer to use. Some technology needs to be developed to do this with ease.

 

[rich apollo]

…when it comes to general printing, I was under the impression that all of the input data goes through the device profile PCS to the four colour device profile…

Depends on the RIP. You can have the RIP add a verification colorbar to the print. You may have control over whether that gets color managed or not.

Hmm. Now, if Epson had a pair of clear inks or varnishes...Todd, I think you've hit on an excellent idea. Swap out the Orange and Green inks for some varnishes with different spectral sensitivity - BOOM! Instant RHEM indicators on every print. Wish I'd thought of it.