Print guy needs best way to make good RGB black and black tints

[Printart]

Banner printer wants files submitted in RGB. All my stuff is layed out in Illustrator in CMYK color mode. Am concerned if I submit cmyk files, when his rip converts to RBG, blacks will print with a red color cast, especially back tints. Willing to change my AI files in house to RGB, however when changing AI color mode to RBG, what was 100%K in cmyk is now R35 G31 B32, and black tint of 60K is R126 G128 B131.

My inclination is to make solid black = R0 G0 B0, and black tints of equal values, such as R125 G125 B125.

Am I on the right track here?

fyi - banner printer has Vutek GS 3250. I do not know RIP.

Thanks

 

[Mrose]

I would say yes. Your on the right track. RGB 000 is the best black.

 

[Typestries]

Printer spends $250k on bangin' printer. Can't (or is unwilling to) print CMYK files. ------->Priceless!

 

[Printart]

Thank you

 

[Hotspur]

RGB or CMYK

The banner printer is correct to ask for RGB.
There is no reason to work in CMYK unless you are outputting to separations.
As he has a Vutek (and probably an EFI rip) the rip will convert whatever you give him - RGB or CMYK files - into LAB and then into CMYK for the printer to output. He won't convert into RGB don't worry.
Working in RGB using RGB input devices and monitors makes sense and keeps file size down from his and your point of view - there is no benefit working in CMYK for this type of output.
The rips output profile will alter any RGB or CMYK numbers, and the depth & quality of black (assuming you are happy with it after assessing on a profiled monitor) will be controlled by the rip profile and printer / ink combination.
As long as you have a deep solid black on screen the amount of black ink is controlled by the rip profile rather than any defined set of numbers in your file.
If the solid black in your file isn't solid black in the print then his profile / media / ink combo is at fault. All your grads and tints should be without a cast - if there is again its down to his profile and output setup not the numbers you are choosing in the app whether you work in RGB or CMYK.
If its grey on your profiled monitor it should be grey on the print assuming controlled lighting assessment.

 

[4R Graphics]

The fact that your banner printer wants an RGB file is stupid period.

If they have the printer set up correctlly and have good profiles (custom made) then there should not be a big problem colors can shift a little but if they have there act together(which from the fact they are asking for RGB tells me they dont) then it should be ok.

Now if you have a profiled monitor and you can get there printer profile (to use in softproof) you can get a good idea of what it will look like.

the big problem with using RGB is that there are lots of colors that you just can not print using CMYK printers (the newer printers have a big gammut but not as big as RGB) CMYK on the other hand has a smaller gammut and newer printers can actually print more colors than the standard SWOP v2 CMYK profile has.

When it comes to blacks and grey and having them be a little pink or green this is a profile thing and if the printer takes the time to really build nice profiles and really dials them in then you can print with out green and pink hues.

Anyone printing wholesale should have really good profiles.


My 2 cents is if they are asking for RGB files only then they dont have there stuff together.

I have built my own profiles for my printer and can hit most pantone colors I can say that without my custom profiles it would be hit or mis on the colors.

 

[rfulford]

I recommend that our clients design in RGB but I would never in a million years ask the client to convert to RGB. First of all, you will not gain anything converting. You will probably not be able to tell the difference between a native CMYK file and a RGB file converted from CMYK if printed on a properly color managed system. CMYK profiles are pretty much all small gamut color spaces. Converting to RGB will only give you a RGB version of your file that matches the CMYK printing condition your profile references such as SWOP or Gracol. Do you want to guess what happens to the file that your convert to RGB from CMYK for your printer? The RIP will convert it back to CMYK so it can be imaged on the GS3250. Now where is the sense in that? The printer should rip your file respecting the embeded CMYK file and let the rip convert from your CMYK input profile to the media specific output profile for the Vutek. Thats 1 conversion. I do not see the sense in pre-converting to RGB and performing 2 conversions total to print.

 

[SightLine]

I agree with multiple points and disagree with some as well. "the big problem with using RGB is that there are lots of colors that you just can not print using CMYK printers (the newer printers have a big gammut but not as big as RGB) CMYK on the other hand has a smaller gammut and newer printers can actually print more colors than the standard SWOP v2 CMYK profile has" This I disagree with for the very reason stated, why if your printer can actually print more colors than the standard CMYK profile has would you dumb your workflow down and limit yourself? We use non-oem inks and have a much wider gamut than cmyk files allow for. We always design in RGB, use our i1 and build all of our custom profiles optimized for Adobe RBG. When we did so, the difference from cmyk was downright stunning. Of course we cannot print the full gamut of RGB but we have a much greater range available using RGB. RGB files are also smaller.... I will agree on the point that converting RGB to cmyk is often a bummer though. Maybe since we are an Adobe shop and our rips (flexi) native rip engine is actually from Adobe helps some, I cannot say for sure. We do create all of our own custom profiles though, and also keep Pantone charts printed and nearly always use Pantone spot colors as well.

 

[Hotspur]

Yes you should avoid converting from RGB to CMYK in your file - there is no sense in doing that.
However the original poster is saying that the print shop prefers RGB files it doesn't mean they can't handle CMYK files - their rip will treat each equally.
It also doesn't mean you should convert your CMYK files to RGB either before sending to them.
All they are saying is where possible please submit RGB which is fine and shows they actually have a good handle on their workflow - many people still think sending CMYK to an inkjet rip is somehow preferable over RGB.

Some confusion on here with regard to color spaces. RGB and CMYK in 8 bit workflows are just numbers of possible colours that our eyes can perceive - there are thus no inherent gamut restrictions at this level.
Monitors, printers etc all have gamut limitations but neither RGB or CMYK are responsible for this - just the analogue restrictions inherent in these devices.

What is alluded to is the gamut restrictions of various color spaces within either CMYK or RGB workflows and here we have the problem.
In general, CMYK spaces are device dependent - you select them for a reason to align with your preferred press. However we have an inkjet workflow here with an EFI rip and thus which press workflow will you select?
There is no correct answer as this is not the intended device so most will select a color space for a generic press device like SWOP without understanding that you are limiting the inkjets gamut by choosing a gamut for some other output device as you are working in CMYK. Then CMYK itself gets the blame for having a "smaller" gamut than RGB - it doesn't of course but as you have chosen a color space for a press with a limited gamut CMYK as a workflow gets blamed.

Working in RGB you also have similar device-dependent color spaces (scanner profiles, monitor profiles etc) that will leave you with the same problem. However, To enable editing of images on RGB devices (monitors) various companies invented new RGB color spaces that were not tied to a specific device and gave neutral grays when equal amounts of RG&B numbers were selected. These are Device-Independant" color spaces and are specifically designed for editing on a monitor - i.e for you to open up and image in an app to edit and send to the output device, like Adobe 1998, srgb etc.
As they are not tied to a device they have their own gamuts which can be larger than many analogue devices (ProPhoto, adobe 1998), or smaller to ensure all devices show the same color (srgb).
Thus people think RGB itself has a bigger gamut - it doesn't, its just that some RGB color spaces do!

Thus if you are not outputting to a press, not only is there often no need to use a CMYK workflow, choosing a press gamut (like SWOP) when outputting to inkjet limits your gamut. If you worked in RGB and used a device-independent color space especially designed for editing like Adobe1998 you do not limit your gamut as much and your file size is smaller.
Any print shop that understands this and asks for files in this format marks them out as unusually competent in my experience - as long as it is only a preference and not a demand as many designers still work in CMYK for inkjet output without questioning themselves why they are so attached to big files and small gamuts.

 

[SightLine]

Good explanation Hotspur! Color management and how colors are interpreted, displayed, produced, etc by differing devices plus adding profiles into the mix is a semi-tough thing to fully wrap ones head around. I just know that years ago when we got our i1 device and started doing our own profiles I had found some long document that explained it pretty well in a way that made sense to me. That is when we changed our workflow over to working almost exclusivly in RGB, using Adobe RGB 1998 as our primary working profile. I do realize this does allow a considerably greater range than what our printer is capable of though.

 

[Terremoto]

Hotspur - very good explanation! A few years ago when I first started using a wide format digital printer I had trouble getting my head around colour management. Did a LOT of reading and research and made the the switch to working in an RGB colour space letting the properly profiled RIP do the heavy lifting. My output is far superior now as a result. There isn't really any reason to work in CMYK unless you're doing separations and then you need the PROPER CMYK colour space for your particular device.

Makes way more sense to just work in RGB (for me it's sRGB cause the boss won't spring for decent monitors).

This thread's likely to get long and ugly - like most of the RGB vs CMYK threads usually do. I'm unquestionably with Hotspur's camp in this debate!

Dan

 

[4R Graphics]

I am neither a RGB or a CMYK guy.

The comments that hotspur and sightline made I will totally agree with.

When I made the comments about CMYK or RGB gammuts it was at the most basic level (where most who do not know much about color managment would be). Most will use either sRGB or adobe 1998 both have gammuts that we can not print even with our custom profiles and others will almost all use the standard webcoated SWOP v2 which has a color gammut that is smaller than our printers gammut.

I do a lot of design and printing in both CMYK and RGB (depends on what it is).

I understood the question to be that his printer only wants RGB files and that he was going to need to redo or convert and well that just means either they dont want to fool with it or he is going to have troubles with getting files that actually look like what he designed.

In order to do this the user will need a calibrated monitor at the very least and almost as importantlly he will want to try and get the printers profile to use in softproofing so that he MAY but may not see the outprofile shifts of his RGB input profile designs ( as you both know something will shift).

My 2 cents