Question about processing Spot colors through the RIP...

Alith7

Well-known member
ok, leading with this... Please don't laugh...too hard...at my stupidity, and yes, we will call it that, cause my dense head was completely MORONIC on this one!

We recently figured out that we have been literally screwing ourselves on spot color jobs and never even realized it!!
Quick background: We run the Xitron Sierra RIP (exact same as the Fuji XMF, they are the same program, different skin), AGFA Accento CTP, and the presses are a Heidelberg SM74 and a Ryobi 524 both with Techkon scanners. We maintain G7 Specs with the use of Fuji's Colorpath Sync package to adjust/maintain curves and such as needed.

Basically, we have to use specific colorbars to work with the scanners and have had a few automated layouts and workflows in place for YEARS to make job processing smooth and efficient(ish).

As such, for ease of our sanity, when we were running jobs on the presses with multiple PMS colors, we would remap them to CMYK(S1) channels in the RIP so that we didn't have to upload and reconfigure custom colorbars for every job. Oops.

We have always had problems chasing PMS colors with screens, problems with screens too open, or no way possible to keep them open and maintain color, just a mess. What we recently realized, with a very intricate 2 PMS + Metallic with screened overlays and all kinds of fun, was that while it's all fine and good to remap to the different channels, each of those channels has a specific curve applied and that they were all different (as they should be for normal 4 color work) to compensate for different ink viscosity and dot gain and such... and we were dumb. basically.

ok, done laughing now? ;) I'm not offended, trust me, laughed at myself when I figured it out. Then cried a little at how I could be so dense as to miss that!?

SO! here's is the question...
How do you handle multi PMS jobs, with colorbars, screen angles, etc. and still keep workflows smooth? I'm not coming up with any great ideas, and looking for some input.
Can't use the same channel, because the screens wouldn't work then, also the color bar wouldn't work.

Thanks for your help!
 

gordo

Well-known member
[SNIP]
We recently figured out that we have been literally screwing ourselves on spot color jobs and never even realized it!!

[SNIP]
Basically, we have to use specific colorbars to work with the scanners and have had a few automated layouts and workflows in place for YEARS to make job processing smooth and efficient(ish).

As such, for ease of our sanity, when we were running jobs on the presses with multiple PMS colors, we would remap them to CMYK(S1) channels in the RIP so that we didn't have to upload and reconfigure custom colorbars for every job. Oops.

We have always had problems chasing PMS colors with screens, problems with screens too open, or no way possible to keep them open and maintain color, just a mess. What we recently realized, with a very intricate 2 PMS + Metallic with screened overlays and all kinds of fun, was that while it's all fine and good to remap to the different channels, each of those channels has a specific curve applied and that they were all different (as they should be for normal 4 color work) to compensate for different ink viscosity and dot gain and such... and we were dumb. basically.

[SNIP]

SO! here's is the question...
How do you handle multi PMS jobs, with colorbars, screen angles, etc. and still keep workflows smooth? I'm not coming up with any great ideas, and looking for some input.
Can't use the same channel, because the screens wouldn't work then, also the color bar wouldn't work.

I can't speak to your specific workflow - but I will make a few observations that may be helpful.

Unless you specifically tell your ink vendor that the spot ink you need is to be screened and/or overprinted then the formulated ink may not have the correct pigment grind/dispersion to print properly on press.
Here's an example of what a 50% screen of a spot color looked like in a shop I did work with:



Not pretty. I used to come across this issue all the time with shops that were running extended process colors (e.g. red, orange, green, violet) to replace spot colors with process blends. Once the ink vendor understood what we were trying to do they would reformulate and presto changeo the problem was usually solved. Sometimes we had to change ink vendors to solve the issue.

Heidelberg has specific color bars for 5 and 6 color work. Some shops jut run a full width thin bar for the spot colors to measure manually.

Most RIPs cycle through the process colors to assign curves and screen angles (KCMY, spot 1=K, spot 2=C, spot 3=m, spot 4 = Y, spot 5 =K etc.) Sometimes in reverse order. Some RIPs just apply the K angle and curve for all spots. Some shops just apply the curve closest in L value to the process colors. I.e. if a spot color is similar in L value to Cyan then that's the curve it gets, similar to L value to the K then that's the curve it gets. BTW, ISO 12647 was based on a linear film workflow - i.e. all colors had the same curve applied. If you have to apply different curves for each of the process colors then there may be unresolved issues on press (yes I know that's what's done).

gordo
 

Alith7

Well-known member
[snip]
Unless you specifically tell your ink vendor that the spot ink you need is to be screened and/or overprinted then the formulated ink may not have the correct pigment grind/dispersion to print properly on press.
[snip]

That is a good place to start. We recently switched our ink vendor from a local small shop to Van Son, their service has been excellent, I will talk with them and the pressmen on this and see what we come up with.

[snip]
Heidelberg has specific color bars for 5 and 6 color work. Some shops jut run a full width thin bar for the spot colors to measure manually.

we actually have a number of jobs that we run with 3-4 sometimes even 5 PMS colors because they are looking for a color range that is unavailable in the CMYK gamut, so we do prefer to use a color bar.

[snip]
Most RIPs cycle through the process colors to assign curves and screen angles (KCMY, spot 1=K, spot 2=C, spot 3=m, spot 4 = Y, spot 5 =K etc.) Sometimes in reverse order. Some RIPs just apply the K angle and curve for all spots. Some shops just apply the curve closest in L value to the process colors. I.e. if a spot color is similar in L value to Cyan then that's the curve it gets, similar to L value to the K then that's the curve it gets. BTW, ISO 12647 was based on a linear film workflow - i.e. all colors had the same curve applied. If you have to apply different curves for each of the process colors then there may be unresolved issues on press (yes I know that's what's done).
gordo

I know in a perfect world (HA! ;)) they should all be the same, but with assorted press quirks and such...you know how it is. One of our biggest is that our magenta seems to tend to being very thin, and so has a much heavier dot gain, so we have to pull back the curve a good bit to compensate, whereas our yellow tends to be pretty thick, so we have to push the curves a bit. But, that's why we have fancy systems like the Colorpath Sync.

I think, I'm just going to have to establish a whole workflow JUST for spot colors with specific profile curves and what not. I wanted to try to avoid that as it adds another step in the system and opens up another area for errors, but it's better than what we have been fighting with.

Thanks for your great input, as always Gordo!
 

DCurry

Well-known member
You don't need color bars that are specific to every PMS. In my old shop, I had 1 standard color bar that worked on every job. How? In addition to traditional CMYK patches, I also made 4 spot color patches and named them Spot1, Spot2, etc. Then I would remap the spot color bars to whatever PMS was used in the job. The remap could occur in Preps or in your RIP, depending on your workflow and RIP capabilities. When I used Apogee, I had to name the spots in the color bars a certain way and Apogee would automatically do the remapping for me. Any color in the color bar that wasn't used in the job was ignored.

As for screen angles, I configured the RIP 2 ways - one way would always use 45 degrees for every spot color. This kept screened edges nice and smooth and was great as long as you didn't have any duotone or mixed PMS inks. In those situations, which were far less common for us, the spots would cycle through the CMYK angles. I don't recall doing anything special for the curves - I think we used the Black curve for spots.
 

baggie

Member
Hi Tashina - as DCurry suggested there are ways to automate the colour bar problem, although you may need to check some of the specifics with Xitron. In XMF you can simply create the colour bar pdfs (using Illustrator or similar) so that the spot colour patches use colour FUJI:Spot1, FUJI:Spot2 etc. - check with Xitron that this works if you are unsure. There is no need to map the spot colors, rather, the workflow maps the spot colors of the colour bar to the ones that it encounters in the job.
Also, you can leave the workflow to automate the screen angle mapping for you. In the screening section of "Job Settings" select the Angle Mapping tab and make sure that the separation name "Default Spot Angle" is set to "Automatic". Angles will then be intelligently assigned to the colours of the job and this will normally produce a good result without having to map angles manually. Again, I am referring to XMF here so you'll need to verify that this control is also available in Sierra. Good Luck!
 

Alith7

Well-known member
Dan~
because of the Techkon scanners, we have to use a specific colorbar layout, the Ryobi handles 6 colors (which is funny because it's a 4-color press), the SM74 uses 5-colors (again, funny because it's a 6-color press)... so the option of just changing the patches on the color bar isn't an option.

That is an excellent idea with the 45 degree screen angles though! I'll look into switching that.


Baggie~
XMF and Sierra are the same program, so I will look for those settings. our color bars are uploaded into the system, that's why i really didn't want to have to do custom colorbars for every job, but setting it up named with all "spot" colors and remapping to those in the rip is a good idea!
My question though is that screen angles are all fine and good to have it auto select them, but what about the profile curve? any ideas how to assign that? And, what type of curve should I use? or....

---> I have a horrible head cold and I am having a hell of time thinking straight... I'll take a look at these settings next week when my brain isn't floating in boogers...
 

baggie

Member
XMF allows you to have a separate characterisation curve for spot colors, as opposed to process colors. If you have defined this (using Colorpath Organiser in the latest XMF) then your jobs will use the curve automatically when spot colors are encountered. However, it is not possible to apply different dot gain curves to different spot colors; any spot color can be set to either use the "spot" characterisation curve, or use no characterisation.
 

Alith7

Well-known member
I will have to see what is available for options. I'm a few versions behind, and my boss doesn't want to update atm.
 

rich apollo

Well-known member
I've always used the black curve for spot colors. Not necessarily right, but it's worked for me.

Dan is right. You should be able to build a single 6-color bar with wildcard spot names like S1, S2; whatever the conventions of the system are. They should map on the RIP AUTOMATICALLY. If it ain't CMY or K, then it's a spot.

At the press console when building the job, the press operator should be able to specify the colors in the job. If it's a 4-color job then the reader should not look for data in the spot color patches.

Are you running the SpectroDrive? With ExPresso?
 

baggie

Member
If you are running an older version then you should still be able to setup the curves using "calibration manager"' a utility program that runs on the server.
 

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