Hi,
I am sending artwork to be printed on a large-format composite printer. The design emanates from a website background and is therefore in RGB. But that shouldn't be a problem should it? I mean it would be just the same as sending a photo to a composite printer and you never convert to CMYK in those cases.
Anyway, to get the brightest colors/largest color space I have assigned and converted the document to AdobeRGB, but now I wonder: should it suffice to mention to the service bureau that the PDF is in AdobeRGB?
I mean if I convert to CMYK I might get duller colors than possible. If I retain aRGB color space, it's only their ink and paper that sets the limit. If they only know that the PDF is in aRGB they should use that as an input profile and then use the optimum profile for their output, right?
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One other thing I am curious about in connection with this. Why must I embed both RGB and CMYK colour profiles if I want CorelDraw to remember what RGB profile is? I mean it takes 1,75 MB just for the profiles only. If I could embed just the aRGB profile, it would be a lot less, around a few kB I think. And If I want to send it to a composite printer, like above, it wouldn't use the CMYK profile anyway, would it?
I experimented with this some more and I found that if exactly all colors in a drawing are RGB, then no CMYK printer profile will be embedded, only the RGB profile, which is 0,5 kB (aRGB). The difference in my file is form 110 kB with RGB only (aRGB) to 1446 kB with some CMYK objects in the drawing. And the lower number is obtained EVEN if the save dialog says 1,75 MB for embedding the ICC profiles. So, actually there is something wrong with the calculation.
Anyway, my conclusion is that if you keep all CMYK objects away you will get away with a lot smaller file sizes, because only the RGB profile will be embedded, and that is a lot smaller.
I believe you're right; only profiles for RGB will be embedded if there are no CMYK objects in the drawing.Regarding the size (have noticed it too), I guess it's because the file is compressed, including the profiles. Just a guess though.
I've heard people saying that RGB should increase the color space when printing CMYK, but from my own tests I must say the difference is hardly visible (if at all). May very well have something to do with the profiles.
I'm sure David Milisock can give you some info regarding this. I'll send him a message.
Ronny Axelsson said:I've heard people saying that RGB should increase the color space when printing CMYK
Great conversation and thank you for the invitation to join in the dialog.
Ok here is the way it works, and the reason I answer like this is because there is NO STRAIGHT YES OR NO, or yes send RGB or no send CMYK answer. Especially since there is such a wide disparity between the abilities of different graphic technicians, even though the technology is identical amd also the output devices available offer a wide range of output gamut, ranging from the smallest gamut (CMYK web press uncoated) to the widest say on an Epson, HD hex color which is a little bigger then Adobe RGB.
CMYK gamut REGARDLESS OF PRINTING PROCESS is a composite value of the ink set (the hue of the inks) and possible ink density, (media and process related). This is why there are specifications such as SWOP that set controls over the hue of the base inks. Also the need for a media (paper) linearization, ink limit, dot gain curve.
POSTSCRIPT COLOR MANAGED DEVICES
For press processes the rule is ALWAYS WORK IN AND SEND CMYK. Which CMYK is the question? Well in reality the process for printing presses is postscript color management so NO MATTER where you are in the world and NO MATTER where in the world you're sending the CMYK file to printing press, the only governing principle is the TIC (total ink coverage) of the media, linearization, ink limit dot gain curve for the type of work.
So for printing press work send CMYK, a TIC 340 for sheet fed coated, a TIC, 300 for web press coated, a TIC 280 for sheet fed uncoated and a TIC 240 for web press. Standard ECI or SWOP CMYK profiles fit the bill. If you want to test the TIC of your CMYK profile create an Adobe or ECI RGB image with lots of R 0, G 0, B 0 areas in it and convert to the various profiles, read the converted CMYK image with the info docker in Photo-PAINT and set the secondary color to be total ink. I use an RGB test image which has very dark areas and it will when converted to CMYK tell you the TIC of any CMYK profile.
ICC COLOR MANAGED DEVICES
For digital copier print engine devices I recommend that you also send CMYK, the reason for this is that while these devices are most likely capable of accepting and converting RGB the conversions many times not what the user desires. This is because the gamut of these devices while wider then a printing press is not anywhere near sRGB and if you want to use RGB as output then I suggest the output device have a gamut that is near to or exceeds sRGB. Actually the CorelDRAW default of web coated works fine for these devices.
For ink jet printing there are three categories, non-postscript driver based devices, postscript driver based devices and RIP driven devices. There are two sub-categories for RIP devices, RIPS that do not allow the creation of media profiles and those that do allow the creation of media profiles. Now the EXACT SAME PRINTER CAN WORK FOR ALL THESE PROCESSES, they just produce the results that are limited by their interface.
Worst device is the non-postscript driver based device, any version CorelDRAW work in RGB and send RGB and take what you get, attempting to modify profiles will be dubious at best.
Next worst is the postscript driver based device, X4 and older work in CMYK and send CMYK, X5 use any color model you want, attempting to modify profiles will be dubious at best.
A better device is the RIP controlled device that uses pre-configured ICC media profiles. These are canned profiles better then your driver based devices and you can try different profiles for improved performance. X4 and older use any color model you want but USE NATIVE COLOR COREL PUBLISHED PDF ONLY and set the RIP for an assumed color space work flow, (the RGB and CMYK source profiles set in the RIP match Corel) . X5 you can use any color model you want and send PS, EPS or PDF files Corel or Distiller published PDF.
The real question is how good are the people I use for my output? When you know that they it's easier to send the files that will work the easiest and the best.
Thanks for your time and information David. Hope Lars can get something useful out of it.I think the final line pretty much says it all (and here's my free interpretation): Talk to the people who are going to print. Do they sound like they know what they are talking about; follow their advice. If they don't; go somewhere else.
Ronny Axelsson said:If they don't; go somewhere else.
I agree, take the time to find knowledgable people.
Thanks! I don't know if I understand everything in your answer, but I'll contemplate on it a bit.
Anyway, I sent this design to a printer (Adobe RGB embedded) but they printed it assuming it was sRGB i think and the colours came out very flat. They redid it with aRGB as the input profile and ot turned out exactly as I wanted it. And I also got the chance to fix some conversion errors, I had CMYK black for some reason, and it did not convert well (I forgot to check that box) and the black came out a bit light the first time too. Now it was charcoal black, I made all objects RGB alreday in the .cdr file. The background was also used here: http://www.huddingebigband.se/ And I think I had to assign aRGB to get this kind of bright colors. I started from Ruby Red (RGB) and made some variations on that color in the Color styles docker.
Soon the music stands will have the design I enclose and we will change the image on the front page to reflect this. (I'm in the center of the saxes).
Lars Forslin said:They redid it with aRGB as the input profile
Bingo, most printiers don't even know how to use their equipment. When I ws an apprentice I never thought I'd be ashamed to be a printer but the level of professionalisim just embarrases me.
That was because I told them to.
But in connection with that, If I send a PDF to a printer with an embedded aRGB profile. How can they tell? I am not too familiar with Acrobat but I notice there is an Output Preview where you can select Separations or Composite and different profiles. But where do you actually check what ICC profiles are embedded?
Ok here's the rub, a proper service provider opens your PDF in Acrobat and should have a plugin either way is reads the profile. Now many open your PDF in Illustrator. If they set their RIP to use embedded profiles it does so with no effort on their part.
Either way with an embedded profile if it is not working it is because they did it wrong.
This does not apply to press work.
Even the best profile isn't going to be the best printer method. It sounds like they have tried to make you happy by applying a profile to the printer. What a waste of time! The best output is achieved by NOT applying a profile to the printer and just letting the printer driver do the work. The driver is designed meticulously by the manufacturer to make the printer sing. For a profile to work at the printer level means matching the ink, paper etc and doing a not effortless profile creation. I did this and it was a waste of a week! Least as far as the Epson goes, no profile on the printer always gets the best result. It's easier to do a print test then make an adjustment to the driver (Epson Windows) if required.
The profile used in the document doesn't cause a "flat image". Applying a profile to the printer does.