purple blues
- Thread starter Jsnapp
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printerpete
Well-known member
usually if running on press with magenta and then cyan you would get a 'bluer' blue but also obviously depends on the mix your using, like 100c and 100m will always turn out purple no matter what anyone says
Stephen Marsh
Well-known member
It depends on whether you are looking for a fix at the colour profile so that RGB to CMYK conversions are correct "out of the box", or to colour correct after the conversion to CMYK (Do you just need to fix raster data, or vector and raster and what is the source, native files or PDF etc).
Something to keep in mind is that the ratio of M to C varies on the L*a*b* lightness value of the blue. Darker blues can have a higher ratio of magenta to cyan - while lighter blues have to be more conservative with much less magenta to cyan.
Similar to gray balance, this ratio is not linear and varies with the lightness of the blue hue, which is why designers often run into trouble when they "tint" a solid four colour to say 25%, as the ratio of M to C is too hight at the lower tint %.
Stephen Marsh
Something to keep in mind is that the ratio of M to C varies on the L*a*b* lightness value of the blue. Darker blues can have a higher ratio of magenta to cyan - while lighter blues have to be more conservative with much less magenta to cyan.
Similar to gray balance, this ratio is not linear and varies with the lightness of the blue hue, which is why designers often run into trouble when they "tint" a solid four colour to say 25%, as the ratio of M to C is too hight at the lower tint %.
Stephen Marsh
Stephen Marsh
Well-known member
Some random thoughts/questions include:
* Why can't the press match the proof?
* Is the problem with the proof or press?
* Who should be fixing this issue? Is it a proofing issue, a press issue or a file preparation issue?
* PDF = Raster only, vector only or raster and vector?
* Who makes the colour in the PDF file? An external client or is the colour created in-house?
* How is the incorrect colour being generated? In an ICC conversion from say RGB to CMYK - or is it being specified direct in CMYK?
* How will you "fix" the colour? Using a better or corrected ICC profile, or manually changing the values in the raster and or vector objects? What software will you use to edit the PDF file content?
* How will you know what is a "correct" blue that is not purple? Will you do inkjet proofs or run test swatches at press or use L*a*b* measurements or something?
As you can see, there are many questions and considerations. In order for the forum to help you better, you will need to give us more information!
Stephen Marsh
* Why can't the press match the proof?
* Is the problem with the proof or press?
* Who should be fixing this issue? Is it a proofing issue, a press issue or a file preparation issue?
* PDF = Raster only, vector only or raster and vector?
* Who makes the colour in the PDF file? An external client or is the colour created in-house?
* How is the incorrect colour being generated? In an ICC conversion from say RGB to CMYK - or is it being specified direct in CMYK?
* How will you "fix" the colour? Using a better or corrected ICC profile, or manually changing the values in the raster and or vector objects? What software will you use to edit the PDF file content?
* How will you know what is a "correct" blue that is not purple? Will you do inkjet proofs or run test swatches at press or use L*a*b* measurements or something?
As you can see, there are many questions and considerations. In order for the forum to help you better, you will need to give us more information!
Stephen Marsh
Last edited:
I have been running into this same problem. Pantone Color Bridge converts PMS 286 as 100c & 72m. 72 Magenta make it too purple. I have tried cutting back the magenta but we still can not get the true blue in process. Has anyone tried swapping out cyan with a different ink? if so, any luck? In the past, we have run Rubine Red instead of magenta to get a deeper red.
For ICC profile-based out of gamut RGB to CMYK conversions, Bruce Lindbloom explains the problem here:
How the Munsell Display Calculator Works
How the Munsell Display Calculator Works
rich apollo
Well-known member
You're not gonna' be able to achieve PMS 286 in typical offset printing. Take a look at the attached. The large mass is the color gamut of GRACoL_2006_v2. The blue orb, way down at the bottom, is the position of the Lab coordinates for PMS 286 (I pulled the Lab info from Photoshop). You can see that the color lies WAY outside the colors achievable under GRACoL conditions on a #1 grade gloss stock. Now, you give me a second hit of cyan, and I can get you there.
Something else to keep in mind, bluey blues would indicate poor ink trap between the cyan and magenta inks. The better the ink trap between the cyan and magenta, the more purply your blues will become.
Something else to keep in mind, bluey blues would indicate poor ink trap between the cyan and magenta inks. The better the ink trap between the cyan and magenta, the more purply your blues will become.
Attachments
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If your current printing sequence is KCMY, try KMCY. When you have too much Cyan ist down, the magenta cannot print sharp on top of it. So your dot gain on magenta is too much and perhaps the color will look too purple. I know several printers in the US who are printing successfully wthe KMCY sequence. This seems to be the easy fix, with out getting too technical.
I have a piece with a vignette in the middle that is Light Blue to Dark Blue. I guess I am almost looking to do simulated duotone with say PMS 300 and Magenta? This would allow me to have the deeper blue that is not achievable with cyan? I may be stuck with making a touch plate of blue and the second pass, but would like to avoid it.
rich apollo
Well-known member
With a second hit of cyan you can hit PMS 300. If you've got the units on the press you can run it in one pass - it's really easy. You have to do a little work to set up the file, but that part isn't difficult either.
turbotom1052
Well-known member
i agree with george john. if your printing k,c,m,y try switching it to k,m,c,y. There is no reason you wouldnt be able to achieve pleasing color with this ink sequence and it will surely help the the magentas dot gain. I run this as a default color sequence with no problems that couldnt be fixed by a little fine tuning of profiles.
dabob
Well-known member
not blue enough . . .
not blue enough . . .
In my experience when you start with a blue like cyan and then start adding magenta and a little black . .. it has to go purple . . its just a limitation of the process if you are going to do a 2nd hit of cyan . . . . why not just a touch plate with the right blue in a mix?????
the truest blue you will get with standard 4/c is cyan . . .
my 2 cents worth
not blue enough . . .
In my experience when you start with a blue like cyan and then start adding magenta and a little black . .. it has to go purple . . its just a limitation of the process if you are going to do a 2nd hit of cyan . . . . why not just a touch plate with the right blue in a mix?????
the truest blue you will get with standard 4/c is cyan . . .
my 2 cents worth
Lukas Engqvist
Well-known member
@dabob, well that does depend on your definition of blue does it not?
dabob
Well-known member
definition of blue
definition of blue
Lucas . . . not to be argumentative but could you make any blue in the cmyk range that does not have cyan as the majority component???? and when you add red to blue its going to go purpler not bluer at least that is what I've experienced over the past 40 years. What I call a "blue" is somewhere between a 2736 and a 300 pantone and the process equivalent is a distinct purpler version of the "true blue" pantone color.
definition of blue
Lucas . . . not to be argumentative but could you make any blue in the cmyk range that does not have cyan as the majority component???? and when you add red to blue its going to go purpler not bluer at least that is what I've experienced over the past 40 years. What I call a "blue" is somewhere between a 2736 and a 300 pantone and the process equivalent is a distinct purpler version of the "true blue" pantone color.
Lukas Engqvist
Well-known member
@dabob, sry I mesinterpreted the ... Thought you were saying that Cyan in itself was the truest form of blue. I guess it was me having an IO error ;P
Lukas Engqvist
Well-known member
Neighbour has sheep dogs… herd sheep… herd ducks…*
Hmmm… there are alot of stray cats around here, >
Hmmm… there are alot of stray cats around here, >
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