I've been told by printers in the past that they want my artwork in RGB so they can print in CMYK. That makes no sense to me. These were garment printers and the like. We are now printing direct to disc on DVDs and CDs. The printer we are looking at buying also told us that our artwork needs to be in RGB and will print in CMYK. He said that 99% of CMYK printers need the artwork in RGB and then the printer does their own conversion to CMYK. Can anyone shed light on this? I don't understand at all!
Please help me understand the CMYK RGB workflow!
- Thread starter WillBEL
- Start date
Lukas Engqvist
Well-known member
CMYK is device specific and complex to define colours since many colours can be defined in alternate ways. RGB is easier to work with since one colour has one set of values. Once the device and substrate are finalised an ICC conversion can be done to the correct output values. If you work in CMYK the risk is you may get too much ink coverage for the substrate causing smearing and the like. Converting to the wrong CMYK will give you undesired colours, so RGB is a better "intermidiate" or general purpose colour space.
Many consumer devices will not even accept CMYK data but will asume data to be sRGB and convert to CMYK as they print.
Could say more but i think it covers the basic principle.
Many consumer devices will not even accept CMYK data but will asume data to be sRGB and convert to CMYK as they print.
Could say more but i think it covers the basic principle.
Thanks for the reply. Where I get confused is say when I create a logo with only 100% CMY according to Adobe Photoshop values. 100% Cyan, 100% Magenta and 100% Yellow. Wouldn't it be easy to print from CMY toner with those values? Or are you saying that Adobe's CMY values differ from the devices? Even then, just print from each color, right?
michaelejahn
Well-known member
WillBEL,
100 cyan can look quite different depending on what 100 cyan is printed on. All paper is not the same white. if you want a color that looks like 100% cyan on newspaper for example, there is already an amount of tone on that paper, so you might have to send less than 100% cyan to make it look like 100 cyan - does that make sense ?
I will suggest three things.
1. If they absolutely need RGB, make the files RGB for them - you can certainly work in RGB mode in Photoshop, Illustrator and InDesign.
2. Ask them what color profiles might be applied to the artwork - specifically, ask "what should my Color Settings be ?" - under the Edit Menu in Photoshop, Illustrator and InDesign, there is a menu item named Color Settings - ask them to send you a screen capture of what setting they would use if they were creating the artwork. If you are working with multiple vendors, and they all are using different settings, raise holy hell (smile)
The fact is, that they are NOT using the same CMY or K pigments in their printing devices. For example, on my EPSON WT7900 printer, the Cyan is actually two cyan ink cartridges - a very very vivid cyan -- and a lighter color cyan - when I examine a patch that was 100 cyan in my pdf - it is really a tint combination on tiny spots of this much deeper cyan and that lighter cyan - and a little magenta too.
BUT - when I measure that with a spectrophotometer - it measures identically as would a 100 cyan patch on a printing press.
Since the printing system is different than a traditional printing system, they are asking you to NOT separate incorrectly for them. They are asking that you let them separate the file.
Hope this helps.
100 cyan can look quite different depending on what 100 cyan is printed on. All paper is not the same white. if you want a color that looks like 100% cyan on newspaper for example, there is already an amount of tone on that paper, so you might have to send less than 100% cyan to make it look like 100 cyan - does that make sense ?
I will suggest three things.
1. If they absolutely need RGB, make the files RGB for them - you can certainly work in RGB mode in Photoshop, Illustrator and InDesign.
2. Ask them what color profiles might be applied to the artwork - specifically, ask "what should my Color Settings be ?" - under the Edit Menu in Photoshop, Illustrator and InDesign, there is a menu item named Color Settings - ask them to send you a screen capture of what setting they would use if they were creating the artwork. If you are working with multiple vendors, and they all are using different settings, raise holy hell (smile)
The fact is, that they are NOT using the same CMY or K pigments in their printing devices. For example, on my EPSON WT7900 printer, the Cyan is actually two cyan ink cartridges - a very very vivid cyan -- and a lighter color cyan - when I examine a patch that was 100 cyan in my pdf - it is really a tint combination on tiny spots of this much deeper cyan and that lighter cyan - and a little magenta too.
BUT - when I measure that with a spectrophotometer - it measures identically as would a 100 cyan patch on a printing press.
Since the printing system is different than a traditional printing system, they are asking you to NOT separate incorrectly for them. They are asking that you let them separate the file.
Hope this helps.
The problem is in the fact that the 100% cyan you see on your computer screen (which is, by the way, an RGB device - only simulating cyan...) is different from e.g 100% cyan from your desktop printer. Again, the same 100% cyan, when printed on a high-end proofer, is a different colour. And further, the same 100 % cyan, when printed on your favorite print shop - you guessed it! - is different.
This is the core of the problem: The "device specific" colours are different on every device. If you set up an image where a deep blue sky is, say 100 cyan 30 magenta, *just right* on your favorite print shop production. If you then take the plates and have them printed at another company, you'll get a bit different result. The inks may have been slightly different, the press is transferring different amount of ink on paper, the paper is different... You get the picture...
If your main point is to get solid 100% cyan - and not worry too much of the often barely visible differences between various 100% cyans - you can do as you say: use 100% cyan.
However, if your final printed colour must be accurate - like Coca-Cola red, you cannot do so. You must find the combination of inks to produce just the correct hue of red on each particular printing device.
The recommendation for RGB comes from the fact that the available colour space ("gamut") is much larger in RGB "world". (Cutting corners here a bit: ) Every cyan/magenta/yellow combination can be reproduced on an RGB device. The opposite is not true. You can easily find very saturated colours on RGB images on your computer monitor - or your TV - that just cannot be printed on CMYK inks accurately. The result will look "duller".
So if you use RGB colour space, you allow the printer to make the conversion to CMYK in such a manner that the colours of your job will be reproduced accurately on their macine.
Handling the whole schebang is called "colour management."
This is the core of the problem: The "device specific" colours are different on every device. If you set up an image where a deep blue sky is, say 100 cyan 30 magenta, *just right* on your favorite print shop production. If you then take the plates and have them printed at another company, you'll get a bit different result. The inks may have been slightly different, the press is transferring different amount of ink on paper, the paper is different... You get the picture...
If your main point is to get solid 100% cyan - and not worry too much of the often barely visible differences between various 100% cyans - you can do as you say: use 100% cyan.
However, if your final printed colour must be accurate - like Coca-Cola red, you cannot do so. You must find the combination of inks to produce just the correct hue of red on each particular printing device.
The recommendation for RGB comes from the fact that the available colour space ("gamut") is much larger in RGB "world". (Cutting corners here a bit: ) Every cyan/magenta/yellow combination can be reproduced on an RGB device. The opposite is not true. You can easily find very saturated colours on RGB images on your computer monitor - or your TV - that just cannot be printed on CMYK inks accurately. The result will look "duller".
So if you use RGB colour space, you allow the printer to make the conversion to CMYK in such a manner that the colours of your job will be reproduced accurately on their macine.
Handling the whole schebang is called "colour management."
Lukas Engqvist
Well-known member
YES! the CMY values will look different on different devices. Each ICC profiles defines the exact appearance of C, M, Y and K for that device. (Usually by measuring about 1000 colour patches) Now an ICC profile will also measure the paper since the paper colour does affect tones of 5% cyan etc.
So in your application you define your target CMYK and then you can simulate how it will look, and measure the values.
Also what colour is 100 C 100 M 100 Y? If you are printing you are ending up with about as much goo as the paper can handle, and if you are printing on newspaper then you are definately toasted. (Actuallt 300% toner on a toner device can also be problematic but not from the goo but that it peels from being too thick a layer of pigment. On an inkjet it may also bleet or show through on the back of the paper)
Now consider (on coated paper) 100 C 100 M 100 Y and the colour 65C 60 M 60 Y and 70 K = 45% less goo on the paper but the same colour. There are many different combinations of CMYK that will produce the same colour on the same paper. But also the same CMY or CMYK values will produce DIFFERENT colours on different papers and with different printing techniques. All depending on the inks/toners and paper.
PLEASE also note that pantone colours also give different colour on different substrates even if the colour is from the same bucket!
If you want a precise result you will have to learn to define colours precisely and learn how to manage them every step of the way.
So in your application you define your target CMYK and then you can simulate how it will look, and measure the values.
Also what colour is 100 C 100 M 100 Y? If you are printing you are ending up with about as much goo as the paper can handle, and if you are printing on newspaper then you are definately toasted. (Actuallt 300% toner on a toner device can also be problematic but not from the goo but that it peels from being too thick a layer of pigment. On an inkjet it may also bleet or show through on the back of the paper)
Now consider (on coated paper) 100 C 100 M 100 Y and the colour 65C 60 M 60 Y and 70 K = 45% less goo on the paper but the same colour. There are many different combinations of CMYK that will produce the same colour on the same paper. But also the same CMY or CMYK values will produce DIFFERENT colours on different papers and with different printing techniques. All depending on the inks/toners and paper.
PLEASE also note that pantone colours also give different colour on different substrates even if the colour is from the same bucket!
If you want a precise result you will have to learn to define colours precisely and learn how to manage them every step of the way.
Johu
Well-known member
Also you said that you will print directly to a DVD. Are we talking about press prints (more like screen printing in the case of DVD) or some sort of printer printing directly to a DVD. If it is a printer then it is most likely that the printer has larger color gamut than your regular CMYK profiles which is why you should keep your artwork in RGB in order to reproduce it with the largest possible printer gamut. And as the other said please ask for the profiles they are working with. This way you can be more certain that even if your logo is defined as CMY(K) you can translate them in to RGB with as true colors as possible.
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