CMYK and Bitmaps

[jens g.r. benthien]

Well, appears to me you are one of the few savvy printers who know how to manage a RIP and the rest of his tools.

[Harry W.]

Hello raccoon2.
Quote "We print on our wide format printers all graphics as CMYK and photos at 300dpi in RBG, and have perfect results every time".

I am puzzled - RGB and CMYK color space being used as the input at the same time!
What file format do you ask for so that you can do that?
Thanks
Harry

[Charles Moir]

If you deliver your work as a PDF file, then you have complete control over what colours are used and can include both RGB and CMYK in the same file.

Bitmaps will be RGB and should retain their brightness (their RIP will do the separation of that). And then for coloured objects and text you can define them to be whatever RGB or CMYK colour you require. And defining 'black' to have some cyan and magenta values as well as 100% black, will give a very rich deep black, as Jens says.

[Harry W.]

If you deliver your work as a PDF file, then you have complete control over what colours are used and can include both RGB and CMYK in the same file.

Bitmaps will be RGB and should retain their brightness (their RIP will do the separation of that). And then for coloured objects and text you can define them to be whatever RGB or CMYK colour you require. And defining 'black' to have some cyan and magenta values as well as 100% black, will give a very rich deep black, as Jens says.

Thanks for your reply.
Yes, but doesn’t it boil down to the type of printing machine and its driver. If the machine is a CMYK only device, won’t the RGB photos in the PDF be printed at CMYK not RGB?
I appreciate if the machine has more inks available (such as Hexachrome) then RGB could be converted into the spectrum of the device through its driver.
At the end of the day it is the type of machine that decides how the RGB photographs are printed not the PDF file it receives. The point is, I suppose, that one should always check with the printer first to make sure that he can print them at RGB; his RIP has the necessary profile for RGB input and can accept Xara’s PDF export, otherwise he will be disappointed to find that they have been converted to CMYK.
In my experience the usual answer to that question is that the printer cannot/will not print photos at RGB.
Regards.
Harry

[Charles Moir]

Well at some point the printing process will be converting RGB colours into CMYK inks, and so it's just a question at what stage this conversion occurs. All printers are CMYK devices - there's no such thing as RGB printer.

More and more printers are accepting general PDF files that contain CMYK and RGB data and just use the inherent separation capabilities of their RIP to convert any RGB data into CMYK.

(And if you think about it printing photos on your computer to your local inkjet is doing the same - it's converting your RGB data into CMYK. In this case the conversion is done by your printer driver)

On the other hand there is PDF/X which is a CMYK-only subset of PDF. PDF/X files must have all data converted to CMYK.

So yes you need to talk to your printer and find out what he expects. Often they will be happy to accept any PDF, but sometimes it may be PDF/X variant, in which case it will be necessary to use third party software, such as Adobe Acrobat 7 to produce the PDF/X file.

[Harry W.]

Well at some point the printing process will be converting RGB colours into CMYK inks, and so it's just a question at what stage this conversion occurs. All printers are CMYK devices - there's no such thing as RGB printer.

Thanks again for your reply.
I fully understand that there are no RGB printers.
I would just add (finally) a selection of the replies I have had to my enquiry whether they could print a number of photos, contained in a brochure, as RGB. It was essential that the RGB photos of objects correctly showed their fidelity, or as near as possible. If left to the printer, without special treatment, they would be converted to CMYK and appear dull and washed out.

1. No. convert everything to CMYK. I have a CMYK only device. Let me have hard copy from your inkjet printer of all the photos and I will print near to it as best I can.
2. No. I have only the basic CMYK inkset. I have no extra inks to increase color fidelity.
3. No. but we offer Hexichrome.
4. No. But I will soon be able to do so, when I take possession of a new printer (Roland?).
5. Yes, My RIP has 2 profiles for RGB and 2 for CMYK. Convert all images and text to CMYK and leave the photos as RGB.

It is, therefore, no good just exporting bitmaps as RGB in a PDF and expecting a printer to deal with them as such, if he does not have the savy or a machine with an RGB profile to do that.

Regards
Harry

[jamesmc]

With todays digital printal services, most are willing to work with the customer.

The large format printers that use plates and sheets are a different story. They run the color mixes in layers to achieve the desired color and its a much more expensive process than small service printers. People that publish magazines or huge quantities of posters, use this type of plate/sheet method. Always a good idea to ask for a 'proof' in either method, but more important with plate/sheet printing.

Hopefully one day we will get away from spinning drums, rollers and multiple paint layers to achieve color.

[Charles Moir]

Actually there is a way of converting everything to CMYK in Xara Xtreme. Simply export as a CMYK TIFF file. (The TIFF export dialog has a CMYK option). Export your document as very high resolution TIFF - at least 300 dpi, preferably 600dpi, and pretty much any printer should accept that file.

And yes it's good advice to always provide a printed proof to the printer from your inkjet or whatever, so he knows what you're trying to achieve.