Notorious Blue-to-Purple Colour Shift... Even *After* Using Specified Profile!

[mostro]

We had some business cards printed with a well-known company. Though we've had problems with blue to purple colour shifts before, we hadn't used their specified colour profile, so I won't blame them for that.

This time round we *did* download and use the profile ("ISO Coated v2 300% (ECI)") (*) as requested- or at least I thought we had. Yet the gradient on the back- which was very clearly blue (**) on the original file- came out so colour-shifted that it wasn't even "purplish blue". It was purple (or "violet" as my colleague described it).

Here are versions of the original PDFs we sent to the company and the PSD files that generated them. (***)

http://www.demondecals.co.uk/example-problem-front.pdf
http://www.demondecals.co.uk/example-problem-back.pdf
http://www.demondecals.co.uk/example-problem-front.psd
http://www.demondecals.co.uk/example-problem-back.psd

I appreciate the basic principles behind colour profiles (different devices support different gamuts) and why minor colour shifts may occur when printing (due to colour mapping). But I can't understand why the colour shift occurred in this case, as they were already in CMYK format, and then saved as PDFs using "convert to destination" and the correct destination profile:-

http://www.demondecals.co.uk/save-adobe-pdf.jpg

I notice that the PDFs when viewed in a text editor contain the string "<photoshop:ICCProfile>Europe ISO Coated FOGRA27</photoshop:ICCProfile>", but I don't know where that came from. Anyway, question is, should we have converted it *before* we saved it, like this?

http://www.demondecals.co.uk/current-profile.jpg

In short, is the colour shift our fault for misusing the profile, or is it the printing company's fault?

- Mostro

(*) "Please upload your artwork in either JPG or PDF format (according standard PDF/X-1a:2001 + colour profile "ISO Coated v2 300% (ECI)*")"
(**) 100% C, 90% M, 31% Y, 20% K, if anything fractionally cyan-biased
(***) (Sorry, I had to change the details for reasons of confidentiality, but nothing technical has been altered)

 

[spottypenguin]

Ironically I cannot open your first PDF - it says Invalid Colour Space. I'm no huge expert on this but it 'looks like' you outputted OK but in my experience Photoshop PDFs always seem a it dodgy / less predicatble than Indesign or Illustrator made PDFs.

I think we always have to expect and accept some colour shift but without being able to open your PDFs vey hard to say. Sorry.

 

[Katedesign]

The front looks blue on the pdf and prints blue on my set-up. No doubt Hudson Signs will come along and tell you all about colour - he knows his stuff!
The photoshop file (front) certainly came up with profile Europe ISO Coated FOGRA27 but the back didn't! The colours, I would have said, shouldn't have shifted too far towards purple...

 

[mostro]

Thanks for the feedback.

Ironically I cannot open your first PDF - it says Invalid Colour Space.

Which program were you using?- I had no problems with Adobe Reader.

I'm no huge expert on this but it 'looks like' you outputted OK but in my experience Photoshop PDFs always seem a it dodgy / less predicatble than Indesign or Illustrator made PDFs.

What's the best way of proofing this sort of thing before printing?

I think we always have to expect and accept some colour shift

I appreciate that it's going to be very hard to proof colour matching perfectly.

However, when the colour shift is bright blue to something that's clearly purple, there's definitely a problem! I've tried to accurately simulate the effect of the colour shift here:-

http://www.demondecals.co.uk/colour-shift.jpg

Yes, it *was* that bad! :icon_frown:

 

[mostro]

The front looks blue on the pdf and prints blue on my set-up.

Hey, thanks for going to the trouble of printing it out. :thumb:

Do you remember which colour profile showed up when you imported the PDF into whatever program you use for printing? It should have been "ISO Coated v2 300% (ECI)", but I'm not 100% sure that I got that right. (As you mentioned, one PSD was originally CMYK "Europe ISO Coated FOGRA27", and the other was CMYK "U.S. Web Coated (SWOP) v2", but I was sure I'd selected the correct conversion options to "ISO Coated v2 300% (ECI)" when I saved it as a PDF- and I know by checking in a text editor that both output PDFs *do* include reference to that, so I clearly didn't forget! :icon_smile.

Should I have converted the original PSD file to the new colourspace using "convert to profile" (see above) *before* I then saved it as a PDF?

Even if there had been a colour shift when it was converted during saving as a PDF, why didn't that show up in Adobe Viewer? (As you say, it showed blue and printed blue on your setup).

Should (ideally) the printing company have sent us some sort of proof before printing?

Is it possible that the (cheap) printing company themselves messed up and/or weren't careful with this? If I knew for sure it was their fault, I'd be happy to tell my boss- who doesn't seem too bothered himself anyway!- this, but obviously I'd rather know if the mistake was mine.

The colours, I would have said, shouldn't have shifted too far towards purple...

Yes, see the comment above- the colour shift really *was* that bad (and way beyond the minor differences that would only show up when different pieces were being shown together).

 

[HudsonDisplayServices]

Hi Mostro...

It's always sad when I read stories like this, as it's completely unnecessary. DIGITAL colour communication is about DIGITS. Numbers. And there's nothing soft or blurry about them - they're hard and fast. "Colour shift" is nonsense... say what it really is! It's poor colour communication or poor colour reproduction - or both.

If you specify a colour accurately a good printer will either output that colour, or tell you that it can't be output in that way on that stock. That gives you the choice of changing method to hit the colour, or changing colour to the limits of the method. If you don't understand digital colour to the extent that you can demand that of your printer you'll use printers that don't demand that of themselves - and when it comes to a problem you'll have no ground to stand on. What tolerance do they work to? How far out is the colour from what you wanted? Not in soft terms like "purpley", "colder", "warmer" - what colour is "purple" anyway? Those are terms my child uses to choose crayons. Colour difference is measured in dE "delta E" - and if the colour you got is within 3-6 dE I'd deem it an acceptable match, anything above 6 needs to be looked at and anything above 9 is way out. Colour Tolerance - how close is close enough? | Hudson

Anyway my point is it pays to have some knowledge of colour spaces and colour profiles as a designer, and you don't need a degree in colour to put them to good use. Before I comment on your issue, here are some vital general points:

1) In Adobe CS you can't NOT work in a colour space. You can't turn colour management off. If anyone says you can, give them a gentle slap from me.

2) The many CMYK and RGB colour spaces you can work in are DEVICE SPECIFIC
- This is the critical thing to understand. 90% Cyan in one colour space represents the colour you see when you print 90% of a SPECIFIC cyan ink, on a SPECIFIC machine, set to SPECIFIC settings, on a SPECIFIC media. Remember this next bit as it's critical to understanding digital colour. If you run that same 90% Cyan colour instruction in any other colour space, you'll get a different colour. If you specify a colour space, and colour numbers, you are specifying a specific colour and you should get no UNEXPECTED colour shift from a printer that knows what they're doing. They may tell you that they can't print the colour you've specified - if it's out of the range of the ink/machine/media combination you've asked for.

3) Even "standard" colour spaces are device specific... Adobe CS ships with the NA standards set as default. Your PS files are constructed in the US Web Coated SWOP colour space, which is the CS default CMYK space. I've written about SWOP as the CS default here... SWOP Specifications - Relevant to Wide Format printing? | Hudson (I find it odd that Adobe ship with it, and odder still that so many designers don't change that immediately.) So what you've constructed is a file whose numbers specify colours as they look if output on a SWOP certified press, on a specific stock.

4) If you CONVERT between colour spaces the COLOUR STAYS THE SAME, which if you've understood point (2) you'll realise means the numbers will change.
5) If you ASSIGN a different colour space the NUMBERS STAY THE SAME, which if you've understood point (2) you'll realise means the colour will change.

Now when a printer receives a file that has colour numbers and no specified colour space... he has to assign one. With any luck he'll assign the one you intended - but only one will be right, any other one and he'll be changing your colours.

As far as I'm concerned the designers job is to provide the file that tells me the accurate colours she wants. In any colour space she fancies. My job is to understand the colour I'm being told is wanted, and then to tell my machines the colour that is wanted. And that's the important bit... If the printer is telling you to send your artwork in ISO Coated v2 - that may be because they've got their press set to that standard. In which case if you know how to convert your art to that colour space and send it to them in that colour space, they'll have no excuse for sending you a colour you haven't specified.

So if you're going to use a printer that demands you handle the colour conversion for them, if you can convert successfully and save without further conversion, then you're on safe ground. Personally - if the printer wants me to do the conversion, I want to know why. I choose to handle the conversion precisely because most designers don't know how to. They create a great design and then massacre their file just in the saving of it. (and everyone knows if anyone should massacre the colour in a file that's the printer's job )

So lets get to your files...

Your back PSD is in the small US Web Coated SWOP colour space. The default CMYK space AdobeCS ships with. SWOP is completely encompassed by ISOCoated v2.


What that means is that IF the printer in question can truly output accurately to the ISOCoated standard, then your file could have been produced exactly.

It's a bit odd that your front PSD is created in Fogra27 instead of SWOP. Somewhere along the line a deliberate change in colour space...? The conversion from there to the PDF has resulted in a different blue for the front text. Not massively different, but different. I haven't checked, but if FOGRA27 is larger than ISOCoated, then the conversion may have adjusted the colour slightly - that's probably what's happened there.

To be absolutely safe, I'd have converted all elements of my image into ISOCoated within the prog, and then saved the PDF including all tagged profiles, but there's nothing here that would scare me that I had an unspecified colour. If it wasn't tagged but the output intent was specified, I'd assume that profile throughout anyway.

Because of the mix up of colour spaces I think I'm safe to assume that you're unsure of your ground here. The printer is probably in the same boat. If they've come up with a magenta heavy blue here, either they've correctly understood your colour instruction and printed it badly - or they've misunderstood your colour instruction and printed the wrong colour accurately . Ask them which CMYK space they thought your files were in. If they say ISO coated, ask them why, given the files are in ISO coated, the print doesn't look like the file, and see what they say.

Communication is the key. Printers aren't trying to rip you off. Sure there are no doubt some cowboys, but 99.9% of printers want to get the best out of their machines, and that means getting your colour right. If you're worried they'll be defensive and not engage - tell them things weren't right this time so you want to be certain for next time... If they don't engage... why are you using them?

The Online Colour Management Training Program | Hudson
Half way down the linked page you'll find a free video lesson - the first of the IPA's Colour Management Professional training lessons. When you know this stuff, reading things like "I think we always have to expect and accept some colour shift" is so depressing! Yes, if you ask for a colour that is outside of the capabilities of the machine/ink/media you're printing to you should expect to have to decide how to handle out of gamut colours. Yes, you might deliberately choose to shift some colours to keep the overall impression of an image containing out of gamut colours. But these debates only crop up because people are unsure of how to communicate the colour they want to, and some printers don't know how to print the colour they're asked to! Either way, the result is a guessing game.

In what other field would that happen?

GP: "I think we should remove the 2nd toe"
Surgeon "I know how to chop off a toe"
Patient "if only they'd discussed whether it was the second from the left or the right... or at least which foot!"

Not sure if that's helped much!

 

[Katedesign]

I told you he'd be along!! ^^

If you understand all that at first reading well done! I must admit that I have very few *fingers crossed* colour problems with my files but I use the same few printers again and again. If I'm really concerned about colours I give the closest Pantone or a digital proof that the client would have seen (or sometimes a high quality inkjet). My Photoshop is set to Swop coated. Is that any help?

 

[mostro]

That was a very informative post, thank you very much.

I've ended up asking rather a lot of questions below(!), so please don't feel obliged to answer them all (or any of them)

How far out is the colour from what you wanted? Not in soft terms like "purpley", "colder", "warmer" - what colour is "purple" anyway?

I appreciate that principle in general, but trust me when I say that (in this specific case) the problem wasn't the fine details, but that the background gradient colour shift was so massive it resulted in a *completely* different "crayon" colour, i.e. if you asked a primary school child which colour the backgrounds were they'd say the before was "blue" and the after was "purple" or "lilac":-

http://demondecals.co.uk/colour-shift.jpg

Not worried about what exact shade of purple it was if it wasn't even meant to be purple in the first place. :icon_frown:

Colour spaces [..] are DEVICE SPECIFIC [..] 90% Cyan in one colour space represents the colour you see when you print 90% of a SPECIFIC cyan ink, on a SPECIFIC machine, set to SPECIFIC settings, on a SPECIFIC media.

I assume that most machines are still set up and calibrated to use one of a few "standard" colour spaces though?

4) If you CONVERT between colour spaces the COLOUR STAYS THE SAME, which if you've understood point (2) you'll realise means the numbers will change.
5) If you ASSIGN a different colour space the NUMBERS STAY THE SAME, which if you've understood point (2) you'll realise means the colour will change.

I appreciate what you're saying- without a colour profile any specified "colours" are just numbers, and could map to different colours/shades depending on what default colourspace is used. And that if an image was designed in one colourspace, but a different colour space is assigned (either overriding the original specified one or if the info specifying the original colour space in use was lost), then colour shift could occur due to the fact that value x maps to a slightly different value in the other colour space.

However, I assumed I *had* converted when I saved:-

http://demondecals.co.uk/save-adobe-pdf.jpg

(Note "convert to destination")

Now when a printer receives a file that has colour numbers and no specified colour space... he has to assign one. With any luck he'll assign the one you intended - but only one will be right, any other one and he'll be changing your colours.

Spottypenguin above claimed that one of my PDFs apparently had an invalid colour space when he/she tried to open it. Is there any way of checking what the colour space assigned to a PDF actually is before I send it to the printers?

And should the on-screen display of a PDF in Adobe Reader reflect the colours in the document (within the limits of the fact that my monitor is RGB- not CMYK- and uncalibrated)?

If the printer is telling you to send your artwork in ISO Coated v2 - that may be because they've got their press set to that standard. In which case if you know how to convert your art to that colour space and send it to them in that colour space, they'll have no excuse for sending you a colour you haven't specified.

The problem is that although I thought I *had* specified the correct colour "ISO Coated v2 300%" colour space when I saved to PDF format...

http://demondecals.co.uk/save-adobe-pdf.jpg

...I'm now concerned that I hadn't.

Your back PSD is in the small US Web Coated SWOP colour space. The default CMYK space AdobeCS ships with. SWOP is completely encompassed by ISOCoated v2. What that means is that IF the printer in question can truly output accurately to the ISOCoated standard, then your file could have been produced exactly.

What would happen *if* an image was created in the PS-default "US Swop" but the "ISO Web Coated 300%" profile was *assigned* (not converted) possibly because reference to the original colour space was lost and they had to guess or apply a default?

Or if the file *was* in the correct "ISO Web Coated 300%", but (again) the reference specifying the colour space was lost so the printer assumed it had been created in the "US Swop" colour space (again, *assigning* an incorrect colour space), possibly before *conversion* to ISO coated.

I've heard that blue-to-purple shifts are the most common due to colour space problems. What you said implied that the colour shifts shouldn't be that bad if a *conversion* is done, but it may be more likely with an incorrect colour space *assignment*?

It's a bit odd that your front PSD is created in Fogra27 instead of SWOP. Somewhere along the line a deliberate change in colour space...?

I don't know where that came from- it wasn't deliberate on my part.

Because of the mix up of colour spaces I think I'm safe to assume that you're unsure of your ground here. The printer is probably in the same boat. If they've come up with a magenta heavy blue here, either they've correctly understood your colour instruction and printed it badly - or they've misunderstood your colour instruction and printed the wrong colour accurately . Ask them which CMYK space they thought your files were in.

I'll try to contact them, but given that they're an el cheapo large printing company with low prices but (from what I've heard) poor customer service and a tendency to blame the customer if they can, I'm not going to hold my breath...

If they don't engage... why are you using them?

More precisely, why is my boss using them? And the answer is, "because they're very cheap". :icon_blushing:

(They're a well-known and major company that I didn't wish to name as I (a) wanted to figure out whether the fault was actually mine before making any accusations like "OMG! XYZ Printers messed up my colours!" and (b) didn't want to prejudice any discussion.

Thanks for the link to the video lesson- I'll take a look at that when I have time.

 

[mostro]

If I'm really concerned about colours I give the closest Pantone or a digital proof that the client would have seen (or sometimes a high quality inkjet). My Photoshop is set to Swop coated. Is that any help?

The problem is that I'm primarily a web developer/programmer with a passable aesthetic sense, not a printing/design professional- I've no idea about "proper" proofs. I had emailed him some RGB jpegs which should have approximated the final result closely enough for his expectations. (We *were* doing them pretty cheaply!)

The person I was doing the business cards for is easygoing up to a point, and probably wouldn't be concerned about a minor colour shift, but IIRC this time he did note that he wanted them to be blue (and not the purply blue they'd come out as in the past), and as I thought I'd used the correct profile, I thought they should come out okay this time.

They didn't, and I'm still not sure if it's my fault or the printers'. :icon_mad:

 

[HudsonDisplayServices]

I assume that most machines are still set up and calibrated to use one of a few "standard" colour spaces though?

AdobeCS is by default setup to use one of the "standard" spaces - but it can be setup to use any space you have a profile for. Every printer/media/ink/settings combination has its own colour space.

Sometimes companies adjust their machines/ink/media/settings to fall within specified tolerances - known standards. In that circumstance a machine can be "FOGRA Certified", "SWOP Certified" etc. That's the very definition as to what those colour spaces are for. If you run to FOGRA39 in Southend, and someone else runs to FOGRA39 in Barcelona - the same file on the same stock should achieve the same print.


.... without a colour profile any specified "colours" are just numbers, and WILL map to different colours/shades depending on what colourspace is used. if an image was designed in one colourspace, but a different colour space is assigned (either overriding the original specified one or if the info specifying the original colour space in use was lost), then colour shift WILL occur due to the fact that value x maps to a slightly different colour in the other colour space.

However, I assumed I *had* converted when I saved:-
http://demondecals.co.uk/save-adobe-pdf.jpg
(Note "convert to destination")

I'm no PDF expert so I can't advise on the saving options. I think it's always safer to make colour conversions separately. But you can test this. I've just copied your settings when saving your psd back file, and then I've gone back, CONVERTED to ISO within photoshop, and then saved to pdf with the same settings. There is a difference between the two pdf's. Try it and see.

Is there any way of checking what the colour space assigned to a PDF actually is before I send it to the printers?

PDFs are containers. They can contain items of different types each with a different profile. In ACROBAT (don't know if this is in the reader) you can go to Preflight, and look for items using ICC Colour - to list every item and every profile...

And should the on-screen display of a PDF in Adobe Reader reflect the colours in the document (within the limits of the fact that my monitor is RGB- not CMYK- and uncalibrated)?

The fact the screen is RGB not CMYK is irrelevant. But you've answered your own question. An uncalibrated screen won't show you accurate colour, but differences between colours (however wrong they actually are) should be reflected. (depending on just how badly calibrated your screen is of course. If you've got bright whites and high contrast set on your screen you'll just give yourself a headache in all ways!)

The problem is that although I thought I *had* specified the correct colour "ISO Coated v2 300%" colour space when I saved to PDF format...
http://demondecals.co.uk/save-adobe-pdf.jpg
...I'm now concerned that I hadn't.

Hopefully someone here is a PDF expert. I hardly ever create files I just print them, so I'm not much use to you here. My eyes are telling me that your PDF image is NOT in ISO Coated, and your colours change when it's incorrectly assigned. Try the conversion in PS i mention above, and see if that file looks more like the item you received.

I've heard that blue-to-purple shifts are the most common due to colour space problems. What you said implied that the colour shifts shouldn't be that bad if a *conversion* is done, but it may be more likely with an incorrect colour space *assignment*?

CONVERTING tries to keep the colours the same wherever possible.
ASSIGNING keeps your numbers the same and changes all your colours.

Assigning the wrong profile will always mess with your colours. Certain colours are more visibly affected by these changes. Pale neutrals potentially, deep blues, bright cyans/turquoises, oranges, pale greens... It's best to think that ALL colours are affected, and to avoid miscommunicating at all!

I don't know where that came from- it wasn't deliberate on my part.

Well you probably want to keep an eye on that!

RE: Cheapo... If you look at this forum (and any other on similar subjects) you'll find the same blend of "where's the best place to get CHEAP print..." and "the printer messed up my colours". People actively celebrate finding people who supply cheaply, and then wonder why machines are being run by low paid people without training/skills etc... I'm a firm believer that if you think of hassle/let downs/your own time/damage to your business/credibility etc as different currencies then most printers cost exactly the same price! You just choose to pay that price in a currency other than money. Best value is represented by the firm that comes in cheapest when you factor in all of those costs, not just the invoice value isn't it?

Anyway - I stray off topic into familiar ranting ground - paying peanuts and expecting to attract something other than monkeys! I'll get back on to pondering why designers are often scared of colour management and ICC profiles and what to do about that.

It's vital for web work too. iPhone4 and Colour Management | Hudson (this article was written before the latest IE which sorted out it's handling of ICCs - but what we've been discussing in terms of putting a file on a different printer/media is exactly the same when it comes to browsers. When you want to communicate colour between devices - a basic understanding of ICCs is as important as understanding screen resolution, file name conventions, or any of the other black arts you web guys mess about with.

Hope that helps!

 

[mostro]

Sometimes companies adjust their machines/ink/media/settings to fall within specified tolerances - known standards. In that circumstance a machine can be "FOGRA Certified", "SWOP Certified" etc. That's the very definition as to what those colour spaces are for. If you run to FOGRA39 in Southend, and someone else runs to FOGRA39 in Barcelona - the same file on the same stock should achieve the same print.

I assume that the profile would have to be assigned to the combination of the machine, the inks used and the paper stock (e.g. if one uses different paper, that would possibly affect the gamut or other aspects of the printing if the controller/printer wasn't aware that a different paper was being used).

.... without a colour profile any specified "colours" are just numbers, and WILL map to different colours/shades depending on what colourspace is used. if an image was designed in one colourspace, but a different colour space is assigned (either overriding the original specified one or if the info specifying the original colour space in use was lost), then colour shift WILL occur due to the fact that value x maps to a slightly different colour in the other colour space.

Yes, that's what I understood you to mean, thank you.

I'm no PDF expert so I can't advise on the saving options. I think it's always safer to make colour conversions separately. But you can test this. I've just copied your settings when saving your psd back file, and then I've gone back, CONVERTED to ISO within photoshop, and then saved to pdf with the same settings. There is a difference between the two pdf's. Try it and see.

Unfortunately, I couldn't replicate this.

PDFs are containers. They can contain items of different types each with a different profile. In ACROBAT (don't know if this is in the reader) you can go to Preflight, and look for items using ICC Colour - to list every item and every profile...

Not that I can see, and I don't have Adobe Acrobat itself.

RE: Cheapo... If you look at this forum (and any other on similar subjects) you'll find the same blend of "where's the best place to get CHEAP print..." and "the printer messed up my colours". People actively celebrate finding people who supply cheaply, and then wonder why machines are being run by low paid people without training/skills etc... I'm a firm believer that if you think of hassle/let downs/your own time/damage to your business/credibility etc as different currencies then most printers cost exactly the same price!

I'd have to say I wouldn't expect too much from that printing company at the price (and given their apparent reputation). Still not too sure if the colour shift was my responsibility or not, but the only way to be sure would be to convert within Photoshop, convert again when saving to PDF (which should have no effect if already converted), double-check that the PDF has the correct profile somehow, then send them to the printers and see whether they come back correct or not.

I think I'm just going to have to leave this for now and see whether or not the recipients of the cards consider them acceptable. :icon_eek: