Inspiring

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Prepress for digital printing

Forum|Forum|3 years ago
October 20, 2022
4 replies
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Sometimes I'm printing designs or simple books at small and inexpensive digital printshops. They usualy have some Xerox, Konica Minolta or something like that and they do not offer offset printing. They're not certified for any standard. I've never understood how their digital presses work in terms of color management.

For example, you make a design in RGB and you convert it to CMYK and then you print both versions, but the results are (more or less) the same on paper. You can simply use the RGB version only.

The results look nice and shiny, but how accurate they are - that's another question. That's not exactly what I see on my monitor, but then my monitor is not professionally calibrated, so I'm not sure.

I became even more confused after I learned about the High Chroma printers. Once I printed on such machine and the print was too reflective and too bright, the colors were too vibrant and everything was too sharp, which on one hand looked cool, but on the other hand it brought some unwanted artefacts to the surface. It was not like that on my screen. The print also had a sort of grainy texture that I didn't really like.

So in short, the question is: when you prepare material for digital printing, how do you set your color management, how do you set the simulation in Acrobat's Output Preview and all that? With offset printing things are more clear to me.

I tried to find ICC profiles or something like that for these digital presses, but I couldn't.

Thanks

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Correct answer rob day

you should have had better rsults, not worse.

I think it it’s also worth emphasizing that an Export to a PDF/X Standard with any CMYK or Gray profile set as the Destination, would almost guarantee color management problems. All of the CMYK color would be DeviceCMYK, and there would be no embedded source profiles needed for the conversion into the print space. The only hope would be if the driver recognized the PDF/X Output Intent as the source.

S

sd5e8aAuthor

Inspiring

Thanks everyone for your replies. I find the following ones most interesting:

Sometimes you can find a RGB profile for the device on the company's website, but the device owner may need to log in to obtain it--you will have to ask them. This will be a "canned" profile but is better than nothing.

Baring that, the printer would need to take on the extra work of creating a custom profile. Technically, this would be done whenever changing the toner or paper stock. Not many of these companies will take on that extra work.

By @Dave Creamer of IDEAS

All of the CMYK profiles that ship with the Adobe apps are for separated offset printing —@sd5e8a is asking about composite digital printing.

A CMYK conversion into a random offset profile would not accurately profile a composite toner or inkjet printer.

an Export to a PDF/X Standard with any CMYK or Gray profile set as the Destination, would almost guarantee color management problems. All of the CMYK color would be DeviceCMYK, and there would be no embedded source profiles needed for the conversion into the print space. The only hope would be if the driver recognized the PDF/X Output Intent as the source.

by @rob day

"If you are designing for Print, use CMYK". Nope. Only if you are sure of what device you are printing to. Otherwise, NO, don't. With digital printing taking over, many printers have moved or are moving to digital workflows using toners/electroinks that have much different colour response, fidelity, saturation and purity than good old offset inks (which are considered the worst technology out there now). Some machines, e.g HP Indigo, or Minolta AccurioPress, can have more than the standard CMYK colours which expands the gamut of what's printable. If you pre-convert, you are throwing away the possibilitry of a better colur match to your source material. You can't get that back, and now you've "baked in" the duller colours.

@Brad @ Roaring Mouse

I don't know which answer to mark as 'correct', all of them are useful.

chrisg11235813

Participating Frequently

If you are designing for Print, use CMYK.

If the print shop you use manages to get RGB files to look like CMYK files, it is because they are using a colour managed workflow, and are converting your files to CMYK. The printshops that produce more vibrant, possibly innacurate colours, are most likely not converting your files before printing. RGB is a larger colour space, a lot of it's colours are out of gamut for CMYK printing.

If you want your monitor to more accuraetly match your prints, you are going to have to calibrate your monitor.

This won't work if you are using printshops that are not colour managed, because their prints can change unpredictably.

Also, if you don't have a high end monitor, a dedicated colour calibrated printer, using a colour managed workflow, there is no real bennifit in trying to calibrate you monitor to match a print. Don't get me wrong, you don't want a monitor that is badly calibrated, but the expectation that your monitor will match your print is not realistic.

Brad @ Roaring Mouse

Community Expert

"If you are designing for Print, use CMYK"

Nope.

Only if you are sure of what device you are printing to. Otherwise, NO, don't. With digital printing taking over, many printers have moved or are moving to digital workflows using toners/electroinks that have much different colour response, fidelity, saturation and purity than good old offset inks (which are considered the worst technology out there now). Some machines, e.g HP Indigo, or Minolta AccurioPress, can have more than the standard CMYK colours which expands the gamut of what's printable. If you pre-convert, you are throwing away the possibilitry of a better colur match to your source material. You can't get that back, and now you've "baked in" the duller colours. Professonal printers who know what they're doing (unfortunately some don't*), theircolour-managed RIPs will take your RGB data and convert it to the best match possible using the toners/inks'etc they have. Even with expanded gamut, you still cannot reproduce everything you see on your monitor, but you can get closer if you let the printer do the conversion. *The fact you got results you weren't satisfied with with the "High Chroma" indicates to me the people didn't know what they were doing with their machine... you should have had better rsults, not worse.

rob day

Correct answer

Community Expert

you should have had better rsults, not worse.

I think it it’s also worth emphasizing that an Export to a PDF/X Standard with any CMYK or Gray profile set as the Destination, would almost guarantee color management problems. All of the CMYK color would be DeviceCMYK, and there would be no embedded source profiles needed for the conversion into the print space. The only hope would be if the driver recognized the PDF/X Output Intent as the source.

Dave Creamer of IDEAS

Community Expert

First, you need to calibrate/profile your monitor. Otherwise, you will not know what to expect. The printer could be accurate and your monitor could be off.

I believe that category of printers like to "think of themselves" as RGB printers, not CMYK. They will convert RGB to CMYK using their built-in look up tables; I think that if they receive CMYK data, it will get converted to RGB and back to CMYK. (Rob Day could jump in here and correct me!)

Sometimes you can find a RGB profile for the device on the company's website, but the device owner may need to log in to obtain it--you will have to ask them. This will be a "canned" profile but is better than nothing.

Baring that, the printer would need to take on the extra work of creating a custom profile. Technically, this would be done whenever changing the toner or paper stock. Not many of these companies will take on that extra work.

In the end, I would expect "good enough" color for high-end laser printers--and would go to a digital _press_ is I want accurate color.

David Creamer: Community Expert (ACI and ACE 1995-2023)

rob day

Community Expert

I believe that category of printers like to "think of themselves" as RGB printers, not CMYK.

Yes I think that is right, all composite printers are going to color manage incoming CMYK values and convert them to new values using the printer’s output profile. So sending CMYK with no profile (Device CMYK), would likely produce unexpected color.

When I don’t know what to expect from an RGB driven composite printer, I’ll have a target page printed—something like the attached PDF, which contains a DeviceCMYK image with pure CMYK gradients, the image converted to ProPhoto RGB, and then to sRGB—two extremely different RGB spaces.

Because of my conversions, the two RGB images get embedded profiles and have a similar color appearance, but radically different RGB values. If they come back with the same similar appearance, I know that the print driver has used the source RGB profiles to make the conversion to its output profile—if there is a big color change, I know the printer is not honoring embedded source profiles. Ideally we want the device to make the conversion from profiled RGB to its output profile, if it is I can work in my preferred RGB editing space and generally avoid out-of-gamut print color.

I can use the DeviceCMYK image to determine if document CMYK values are printing unchanged, or being converted by the driver. If I check the black only ramp under a loupe it will be 4-color if there was a conversion: