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Author Topic: Tell me if i'm wrong here...  (Read 1403 times)

danstart17

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Tell me if i'm wrong here...
« on: August 21, 2017, 07:24:05 AM »

I'm only just getting started with color management and I know it's a long road.

When reading a spot color with an i1Pro2 for instance, should the CMYK values match the values on your screen or is this just not realistic?

Just when I think I have it right, I've read something else and it confuses me more.
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Royce Howland

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Re: Tell me if i'm wrong here...
« Reply #1 on: August 21, 2017, 10:38:57 AM »

The hard & fast answer is -- "it depends". :)

One of the most important things you need to come to grips with is that different classes of devices (cameras, monitors, printers, etc.) have different gamuts, i.e. different ranges of saturated hues, that they can reproduce.

Also within each class of device, there are sub-classes that have very different gamuts. E.g. there are el cheapo monitors that can't produce even nearly the limited gamut of the sRGB colour space, there are decent monitors that can do the full sRGB gamut, and there are "wide gamut" monitors that can do more or less the full Adobe RGB gamut. In terms of printers, the CMYK press environment you're used to working in as a designer has a very different typical gamut than what you'll find with RGB inkjet photographic printers. Within the class of printers, it's further complicated by the impact that the paper itself has on the reproducible gamut -- matte papers are much more limited in what they can reproduce than glossy papers, just as one example.

So when you ask "should the values of a spot colour measurement from a print match the values on the screen", the answer is "it depends". It depends on what the colour value actually is, and whether that value falls within the gamut that both your screen and print technology can reproduce. If it does fall within both gamuts, then yes, you should get a reasonable match. But if the colour value falls outside of one or both gamuts of the screen and/or print, then no, the values will not match.

(There are other variables at play but I'm keeping it at the basics here, to start. One such variable is the concept of rendering intent, which is how colour values -- both in gamut and out of gamut -- are rendered from one colour space into another. Choice of rendering intent can influence the accuracy of colour values that are actually within gamut.)

danstart17

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Re: Tell me if i'm wrong here...
« Reply #2 on: August 21, 2017, 12:35:44 PM »

Hi Royce

Thank you for the reply.

I'm literally just checking a print now, I have a Pantone color bridge book in front of me

I've decided to print page 1 of the book, see below values:

Yellow - C = 0%, M = 0%, Y= 100%, K= 0%
Magenta - C = 0%, M = 100%, Y= 0%, K= 0%
Cyan - C = 100%, M = 0%, Y= 0%, K= 0%
Black - C = 0%, M = 0%, Y= 0%, K= 100%

I've created a new file in Illustrator using the ProPhoto RGB color space and created some blocks with the above values, when exporting to PDF, I export using the following settings:

Color conversion: Convert to destination
Destination: Document RGB - ProPhoto RGB
Profile Inclusion Policy: Include destination profiles

I believe my rip will then use my profile to print it

Does this even sound right or am the problem?

now printed the colors using my new profile and the colors do appear different

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Royce Howland

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Re: Tell me if i'm wrong here...
« Reply #3 on: August 23, 2017, 11:12:37 AM »

Likely the printed colours will be somewhat different than what you see on screen. You're created blocks of maximum C, max M, max Y and max K within the ProPhoto RGB colour space. Taken on its own, ProPhoto RGB has such a large gamut that colours of maximum saturation can not be accurately viewed on your monitor, nor accurately printed on your printer. But the two degrees of inaccuracy are different from each other. So neither one may be a true rendition of the file's internal colour, but they way they different from true will differ from each other.

Now, that's just talking about the theoretically maximum saturation colours that can be represented within ProPhoto RGB. I did a quick test myself, setting up an Illustrator document with blocks of max C, M, Y and K in the ProPhoto RGB document colour space. I exported it from Illustrator as a PDF the same way you described, then loaded that PDF into Photoshop and rasterized it into an 8-bit TIFF in ProPhoto RGB, so I could load the image into some tools. (No time this morning to make actual test prints.) Looking at the colour blocks in Photoshop, I see they are actually quite a far ways away from maximum saturation. So I'd expect that max C, M, Y and K blocks are not a test that will harshly push the envelope of either my display or my printing setup.

Looking at the 8-bit TIFF version of the test file in Gamutvision confirms this. All of the blocks are pretty close to falling within gamut of what my NEC PA302W monitor can display; the differences should be barely visible to the eye. And they are also close to being within gamut of what my old Epson 4880 printer could reproduce on a decent gloss fibre paper such as Canson Platine.

So in my case, with just a quick back-of-the-envelope test set up that should be relatively parallel to yours, I wouldn't actually expect a test print on my setup to look all that different from what I see on-screen. There are all kinds of caveats for doing screen-to-print matching, of course, a big one of which is what kind of ambient lighting conditions exist in the work room where your monitor resides, and where you're looking at the test prints. Suboptimal lighting can fake out your ability to judge how close a print matches your monitor display. And so on.

So a couple of followup questions to help clarify the answer to your question, and why you may be seeing more of a difference between monitor and print than what my quick check may predict. What model of monitor are you using to display your editing work? What model of inkjet printer are you using, and what type of paper are you printing these tests on? What RIP are you using, and are you sure it's using your own custom created ICC profile for output? (Your words were "I believe my rip will then use my profile to print it"... need to be sure. ;) )

digitaldog

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Re: Tell me if i'm wrong here...
« Reply #4 on: August 23, 2017, 11:58:58 AM »

I'm only just getting started with color management and I know it's a long road.

When reading a spot color with an i1Pro2 for instance, should the CMYK values match the values on your screen or is this just not realistic?
Correct, not realistic. CMYK is an output (print) specific highly device dependent color space! The only way to understand the scale and meaning of the CMYK values is by having an ICC profile that defines that output condition. There are colors a display can produce that cannot be defined in CMYK and vise versa. The role of black generation plays a huge role in the numbers that may have the same color appearance too. Case in point: http://digitaldog.net/files/BlackGenCMYK_Skin.jpg
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Andrew Rodney
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danstart17

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Re: Tell me if i'm wrong here...
« Reply #5 on: August 24, 2017, 08:21:57 AM »

Hey guys

I really appreciate your help.

Now I don't work with high-end clients so colours don't need to be 100%, however, I would like consistency.

My work consists of:
    Web Design
    Vehicle Graphics
    Business Stationery

Web design - OK, So I understand we should use the sRGB2.1 colour space. Recently others have been suggesting use Adobe1998 as screens are getting much better.

Business Stationery - I send these to a litho printer which I have no control over, I am told to use ISO_coated_v2 which I believe is based on fogra39.

Vehicle Graphics - I have been using the same ICC Profile as above, colours look dull as opposed to other sign makers graphics. I am using Versaworks RIP with my large format Roland Solvent printer, I keep reading that everyone is using RGB when sending to the printer but consistency plays a part again, if I print business cards with a litho printer using CMYK and a certain profile then start printing vehicle graphics using RGB and another profile, it certainly won't match.


Think I need to go back to basics...

What colour space and profile should I be designing in?

Who do I save the file for optimum output so the colours don't change when saving as an EPS, PDF or TIFF?

I then need to recreate a profile once I have the first part of the settings correct.

Writing this I realise I have no idea about colour management.

Thanks
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digitaldog

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Re: Tell me if i'm wrong here...
« Reply #6 on: August 24, 2017, 09:09:51 AM »

What colour space and profile should I be designing in?
Who do I save the file for optimum output so the colours don't change when saving as an EPS, PDF or TIFF?
From raw, ProPhoto RGB. From a scanner, the scanner profile used to define it's color space. Save as TIFF for bitmapped (raster) images.
That doesn't mean you'll provide TIFF for output, you need to find out what other's in the final workflow require.
Use sRGB for uploading images to the web and mobile devices. Think of it as an output color space just for those needs.
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Andrew Rodney
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danstart17

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Re: Tell me if i'm wrong here...
« Reply #7 on: August 24, 2017, 09:38:00 AM »

Thanks Digitaldog

All images I use tend to be supplied or purchased from stock sites.

Most of my work is vector based graphics in Illustrator, logo designs etc. What profile should I use with that?

Sorry, I am a complete idiot when it comes to colour, I realise that now.
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digitaldog

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Re: Tell me if i'm wrong here...
« Reply #8 on: August 24, 2017, 09:41:47 AM »

All images I use tend to be supplied or purchased from stock sites.

Most of my work is vector based graphics in Illustrator, logo designs etc. What profile should I use with that?
If they are stock, they should have an embedded ICC profile and you use that.

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Andrew Rodney
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danstart17

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Re: Tell me if i'm wrong here...
« Reply #9 on: August 24, 2017, 09:50:11 AM »

Hi Digitaldog

Sorry, I meant what profile should I use as a standard for when i'm designing my logos, bearing in mind that it will be used on the web, vehicles and stationery?
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digitaldog

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Re: Tell me if i'm wrong here...
« Reply #10 on: August 24, 2017, 09:59:36 AM »

If they are stock, they should have an embedded ICC profile and you use that.
If you're creating from scratch, ProPhoto RGB or Adobe RGB should be fine, convert to sRGB when posting anything to the web.
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Andrew Rodney
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danstart17

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Re: Tell me if i'm wrong here...
« Reply #11 on: August 24, 2017, 11:25:51 AM »

Thank you.

You help is much appreciated.

OK, happy with that part now, what PDF settings should I use to get the best output?

I just tried saving as an EPS but the image dulls down a lot and more than expected just for an RGB to CMYK conversion. I'm using one of your images with the fish in the top left and the guy in the blue shorts in the boat.


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digitaldog

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Re: Tell me if i'm wrong here...
« Reply #12 on: August 24, 2017, 11:27:26 AM »

OK, happy with that part now, what PDF settings should I use to get the best output?

I just tried saving as an EPS but the image dulls down a lot and more than expected just for an RGB to CMYK conversion. I'm using one of your images with the fish in the top left and the guy in the blue shorts in the boat.
Can't answer that as it's output specific. Depends on the output.
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Andrew Rodney
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Stephen Ray

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Re: Tell me if i'm wrong here...
« Reply #13 on: August 24, 2017, 12:48:46 PM »

Some things to be aware of when using Illustrator and Pantone spot colors (which you’ve specifically mentioned)….

Don’t change a spot color name in your file. A Pantone-savvy RIP expects to see the original factory name and will use its internal Pantone color look-up tables when it interprets the Illustrator file. A RIP admin / user can modify RIP Pantone color look-ups to further match colors if necessary.

A Pantone spot color is just that, a spot, and not a blend. If you convert the spot to a blend you have changed from the realm of a named color library system (recipe / measurement) into another realm such as CMYK and therefor color management methods (recipe / measurement). Same goes for changing a Pantone color name.

I noticed from your post you’ve created an Illustrator file in ProPhoto RGB but you generated a CMYK swatch of 100% yellow. Those are two different color modes. An Illustrator file should be normalized using only a single color mode.

I think your Pantone book uses sRGB for the values of their swatches, not ProPhoto RGB values.
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jwlimages

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Re: Tell me if i'm wrong here...
« Reply #14 on: August 25, 2017, 01:40:16 PM »

Danstart17 wrote:
Quote
I've decided to print page 1 of the book, see below values:

Yellow - C = 0%, M = 0%, Y= 100%, K= 0%
Magenta - C = 0%, M = 100%, Y= 0%, K= 0%
Cyan - C = 100%, M = 0%, Y= 0%, K= 0%
Black - C = 0%, M = 0%, Y= 0%, K= 100%

I've created a new file in Illustrator using the ProPhoto RGB color space and created some blocks with the above values, when exporting to PDF, I export using the following settings:

Color conversion: Convert to destination
Destination: Document RGB - ProPhoto RGB
Profile Inclusion Policy: Include destination profiles

I believe my rip will then use my profile to print it

Does this even sound right or am the problem?

now printed the colors using my new profile and the colors do appear different


-- I'm surprised no one asked what CMYK is your working space. As each different CMYK profile represents a different printing condition (printer or press, inks, paper, calibration, etc.), which one you select is critical. For example, it can be futile to create a design or edit images in a huge RGB color space like ProPhoto if you are then converting to say, U.S. Web Coated (SWOP)v2 for CMYK output - huge ranges of those RGB colors can't be produced in that CMYK space, so they are converted (i.e., crunched) down to the vastly smaller color gamut of "SWOP".

For that matter, even though your RIP may well be able to simulate most of the Pantone colors well, if your print file has already been converted to "SWOP", lots of those colors have been discarded (converted to ones inside the color gamut of "SWOP"), and the RIP cannot magically restore them. If you are running the RIP yourself, the ideal CMYK space to target is that of the RIP itself (including the media), but it is simpler to just send tagged RGB files & have the RIP use those RGB source profile(s) to convert to it's CMYK for output.

A couple notes from the real world of print & web production - take these as gentle suggestions, pls:

1. what profile to use for original design? - since you spec logos for web, vehicles & stationery, start with sRGB. You'll want sRGB for web and for sending files to grand format inkjet & solvent printers (vehicle wraps). For LH or any offset print you'll deliver CMYK - for better color, avoid the infamous US Web Coated (SWOP)v2 profile, check out the idealliance.org site for guidance & profiles. And if possible spec PMS/Pantone spot colors in your CMYK files (not in RGB) to avoid conversions - of course this is moot if you're printing only 4 inks, where the spot color is only being simulated anyway.

* oops, just saw your addtiional note about your printer spec'ing Fogra39 - fine, if that's what they request, just use it. *

2. using stock photos - (good luck! ;-) - usually they are RGB, sometimes tagged with ICC profile, often not. Sometimes they are tagged with incorrect ICC profile (!). In general, if photo has profile attached, use it. If no profile, assume sRGB color (and use Photoshop to Assign that profile to it).

Hope this helps,

John
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Stephen Ray

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Re: Tell me if i'm wrong here...
« Reply #15 on: August 29, 2017, 01:50:01 AM »

<What colour space and profile should I be designing in?>

In your case, I suggest designing in sRGB.

In your line of work you work with many types of files from many different sources from many people with different degrees of knowledge and expectations. There already exists industry-common standards and tools WITH COLOR VALUES enabling you to easily communicate a color with your clients and vendors. At least three of those tools are sRGB monitors, the common graphics software suites with their various color & Pantone libraries, and Pantone swatch books. (Remember your Pantone Color Bridge book has sRGB values.) Business-wise, your Pantone book is a qualified and neutral guide.

Using Illustrator in sRGB color space / mode and when your customer specifies a PMS color, by using your Pantone Color Bridge book you now have RGB values you may use for any type of vector or raster elements in your design so long as you normalize all the elements into sRGB color space.

An example is a design using a specific red PMS logo (vector EPS file) along side a studio photograph (raster TIFF file) of their product labeled with their red logo and another photograph (raster JPG file extracted from a previous PDF brochure) of people in the background wearing red T-shirt merchandise available from the online store. Obviously, you would like the red logo theme to jibe.

Hopefully, you would feel comfortable knowing you have a 3rd party color guide (Pantone) as to what the color should be and the fact you have measured and adjusted all the important colors in your file destined for your websites, vehicle wraps, and business printing. All of those vendors of yours should already understand and accommodate your sRGB files. Most likely you already have an in-house machine which can print the file to your satisfaction too.

The Pantone Color Bridge book is an actual recipe for sRGB colors for certain print conditions.

Yes, you can design in a larger color space than sRGB but you don’t have the benefit of a comprehensive guide with actual color swatches and RGB values or dependable CMYK values amongst your clients and vendors.

More than 20 years ago and before Pantone created their Color Bridge book, shops would generate their own guides with RGB and CMYK values from whatever means they used. Those values were rather closed-looped and specific to their use and their customers only. Since then Pantone has prohibited their use because those charts infringe upon the Pantone brand. It’s OK to print Pantone swatches, just not with values.

I would be interested to know if this helps you sort things out.
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