Design in RGB and Print with CMYK - I'm confused and need some help

[Supermann131]

I'm sort of new to the sign business and overall have either been lucky or something. I come from a different background driven by RGB images and even have some equipment where I'm told to design in RGB. My Brother T-shirt printer and my sublimation printer both want RGB data. My Roland VS-540 seems to give me better results with CMYK data files. I read how VersaWorks converts the CMYK or RGB to LAB and then to their equivalents and that makes sense. My problem is this: We have files from some customers which were designed for their t-shirts in RGB. We know there are colors you cannot print, but it is what it is. Still, how can we design in RGB when sometimes those colors don't print. They could be crucial to the overall design. Of course it looks great on the monitor, but without a bucket of ink into some kind of plate or screen, they don't work! Not sure how to proceed.

 

[Christian @ 2CT Media]

Profile your printer to the way you view your files on screen. I do everything in RGB including create and send print files through ONYX to me HP Latex.

 

[tollerdad]

Most modern printers use light inks or additional colors such as orange and green. These inks result in a larger color gamut than CMYK so if you want to get the most out of your printer design in Adobe RGB. Your rip is designed to know what to do with the rgb file to convert it to print. The exception might be in a campaign situation where you are trying to match cmyk prints off of a print press than you may want cmyk.

Cheers

 

[Biker Scout]

Despite what you think about inkjet CMYK anything... all those printers print in RGB. The RIP software converts the computer CMYK data to nearest neighboring color value of 255 color values of RGB each anyway. The better your profile, the closest match you can achieve. The software estimates ink density values up to 1024 levels per color channel, if your printhead can support that fine of a ink droplet. Which is why having a real spectrometer is of a great value if color matching is your end goal. Consistency from year to year is important, especially if you have repeat clients with demanding color requirements.

Since inkjet printers do not lay down ink in the traditional sense, like on a 4 color press, where the inks are separated out onto 4 different CMYK plates with a line screen that interlays the color halftone and therefore fools our eyes into thinking the colors are blended. Some minute premixing occurs in the air gap between the media and print head, and some bleed occurs before ink dries on media. Really fine, precise droplets can avoid this, but print speeds are greatly diminished.

You can technically design in RGB, as long as you color calibrate your printer's output to your monitor profile settings. That way, there will be no surprises on print output with huge color shifts.

 

[P Wagner]

I'm sort of new to the sign business and overall have either been lucky or something. I come from a different background driven by RGB images and even have some equipment where I'm told to design in RGB. My Brother T-shirt printer and my sublimation printer both want RGB data. My Roland VS-540 seems to give me better results with CMYK data files. I read how VersaWorks converts the CMYK or RGB to LAB and then to their equivalents and that makes sense. My problem is this: We have files from some customers which were designed for their t-shirts in RGB. We know there are colors you cannot print, but it is what it is. Still, how can we design in RGB when sometimes those colors don't print. They could be crucial to the overall design. Of course it looks great on the monitor, but without a bucket of ink into some kind of plate or screen, they don't work! Not sure how to proceed.

Understanding the basics of the ICC-based (open architecture) workflow is the key to this. Most large-format RIPs rely on ICC standard architecture, and the International Color Consortium is responsible for this. The place to start is the ICC web site:

www.color.org

The attached drawing is a very simplified overview of this architecture. At the center of the color-managed workflow is the LAB color model. It is inside of all color-aware programs including design apps (Photoshop, Illustrator, CorelDRAW, Flexi, etc) and large-format RIPs. The ICC profile is really nothing more than a translation table, with one side of the translation being LAB, and the other is typically some varient of RGB or CMYK.

The more representative these translations are to your specific reality (color in the file and your devices' unique behaviors), the better the result, and the inverse is also true. Therefore, the ICC architecture will work with either type of data (RGB or CMYK), but the reality is that most common RGB working spaces (sRGB, Adobe 1998) tend to include more color, versus most commonly used CMYK working spaces (Coated SWOP or Gracol). Large format digital printers will have their own unique gamut based on many factors, including media product, ink limits, etc. Often times (though not always), these can exceed SWOP or Gracol in size.

There is a great deal of misunderstanding of the color managed workflow out there in the user community, and very few are properly leveraging ICC standards by using best practices across the enterprise, including custom device profiles for all of the devices and medias in the workflow (~1 in 20 is my best guess).

 

[bob]

It all depends on just what you're sending to your RIP and to what your rendering intents are set. Bitmap, vector, or gradient.

First pick a profile you like. Contrary to what the profilistas preach, you really only need one or two. For example I'm herding a Mutoh 1204 using Flexi. I find that, with one exception, the Oracal 3651G profile form Oracal, with one adjustment, works everywhere all the time. The one adjustment is using the highest dither algorithm and the one exception is printing on poster paper. For poster paper I use that same 3651 profile with the link limits reduced a bit. Your mileage may vary.

Then...

Bitmaps: Always RGB with the bitmap rendering intent set to 'Perceptual'. This yields pretty much what you see is what you get.

Vector data: Set the rendering intents for vector [and text] to 'No Color Correction'. The print a Pantone CMYK Coated color chart and hang in on a wall. This chart is the truth. When you want a particular color for vector and text data, pick it from this chart. That's the color you'll get.

Gradients: Always create gradients in CMYK. Set the rending intent for gradients to 'No Color Correction' as well.

Do these things and you should be able to print on most anything with acceptable reliability.

 

[tdebruin]

What do I find color profiles for my new VS-540

I have a new printer and use mostly Oracal vinyl and Ultra Flex banner material and I can't find any profiles for those. Anybody know what generic profiles will work in Versa Works?

 

[idsignsil]

I have a new printer and use mostly Oracal vinyl and Ultra Flex banner material and I can't find any profiles for those. Anybody know what generic profiles will work in Versa Works?

For VersaWorks you can download ICC Profiles from the Oracal/Orafol website.

http://www.orafol.com/gp/americas/en/icc-profiles

For the Ultra Flex banner, try the generic banner profiles in VersaWorks and pick one that you like.

 

[AF]

Or even better you can make your own profiles.

 

[Jackpine]

I do everything in RGB including design and printing the files. And everything Bob said. Once you have a work flow one or two profiles is enough. I use General Formulation 202 and 203 profiles and with 202 I lower the ink limits. Printing from a Mutoh 1204 and this worked with a Mutoh Falcon Jr.