Printing RGB information to predict colours - does file format alter outcome?

[CoxynotKirsty]

I have a file that has a matrix of RGB coloured squares on it with their corresponding numerical value.

I want a printer to print that file so I can visually compare those RGB squares to an existing colour I have on a piece of artwork (it's a decal).Once I have that RGB combination, I intend to alter my artwork to suit and am assuming that, everything else being the same (printer, paper, ink, operating system, position of moon), the colour will be identical.

So to my questions.

Can the file type have an effect on the printed output? Ultimately, the artwork will be in illustrator but I am hoping to send the initial RGB matrix as a PDF. The original file is actually an ASCII HPGL2 file.

Or put another way, if I print out a block of RGB colour using photoshop, will that differ from the same colour block printed from illustrator, or CoralDraw?

Does changing the colourspace change the printed output of the file, or is it a system to stop the user selecting a colour that cannot be printed?

Obviously, RGB get translated to CMYK, but at what stage does this happen? Within the graphics program or through the driver supplied by the printer manufacturer?

thanks in advance

[Monika Gause]

Talk about this to the manufacturer of your decals.

Actually this is what color management is there for.

[Mike_Gondek]

coxynotkirsty  wrote

at what stage does this happen? Within the graphics program or through the driver supplied by the printer manufacturer?

Neither if you want good color. You need to change the document color mode to CMYK, and then update the values to the swatch chart for the press you are printing to.

Make sure your PDF settings don't compress colors, and you should be sending a CMYK PDFs for color proofs.

Now I am guessing you do not have a swatch chart or press profiles, so you can then use a PMS book with CMYK swatches. The paper | inks | varnish will be different but this will get you closer than just using the  conversion form Adobe. You need to spend most of your efforts on the large fields of color. Keep in mind you can never exactly amthc all RGB color in CMYK, as CMYK has a smaller and different color gamut.

A hardware color calibrated monitor is very helpful.

[Test Screen Name]

The same RGB colour in Photoshop will print differently according to the RGB profile you select (or don't select, but get by default). RGB isn't a colour, it's a recipe that makes different dishes.

[CoxynotKirsty]

Now that is interesting.

What people are missing is that I dont care what the color looks like on screen.

What I care about is whether the output is the same regardless of the program I use to send the information to the printer.

So is this correct.....

I open illustrator and create a block of color using RGB.

Doing nothing else, I hit print and get, for example, an A4 page with a block of color in the middle of it.

I then change the RGB color profile to something else (god knows how - but that's another matter)

I hit print again.

Same printer

Same inks

Same program

however the output is different?

In my situation I have a one off job that has zero commercial value or consequence.

Assume I do not have access to any PMS swatches and am in able to speak to a printer for any length of time because he's busy and cannot justify the cost.

What I do have, however, is the original artwork which was screenprinted onto clear vinyl, a scan of that artwork that was done professionally and a file containing 32000 color variations ranging from 0,0,0 to 256,256,256 (RGB) - at least I think there are, I never bothered counting them.

This file is actually an ASSCII text file that can be edited in Notepad and could actually be sent to a colour plotter using DOS. It can be read by some graphics viewers and thus converted to PDF.

What at I was hoping to do was to select one of the pages that possibly generated the colour I was after and have the printer print that out for me. I would then select the colour i wanted and proceed from there. The thing I am trying to understand is the consistancy between programs.

In my mind this is the ultimate colour matching system - it takes into account the media, the physical printer - not just the model, it even takes into account the brand of ink used. But in order to work I need the information sent to the printer needs to be unadulterated by the program, or if it is adulterated, it needs to be adulterated the same way each time.

My initial question was whether I could open this file in different programs and still get the same result.

I thnik the answer is no.

[CoxynotKirsty]

Please accept my apologies for anyone who's head just exploded.

[Mike_Gondek]

No you will not get the exact same color by sending an RGB file from different program. In some instances the delta E difference in color may be small and yo may not see the difference, but sending RGB to aCMYK devices does not make sense.

There are very very very few RGB printers , but even printing to a Lambda as as Test Screen Name mentioned the program all have different options for color management, so there will be a color shift.

[jdanek]

"What at I was hoping to do was to select one of the pages that possibly generated the colour I was after and have the printer print that out for me. I would then select the colour i wanted and proceed from there. The thing I am trying to understand is the consistancy between programs."

That would be determined by your Color Settings in the programs.

[Test Screen Name]

You may not care about the colour on screen. But all these apps use colour management to try to match the colour in the screen to the colour on the printer. All these apps use your colour management settings to do this. So the colour of screen and colour on the printer are tied together even if they don't actually end up the same.

Many people run away screaming when "colour management" is mentioned. You can do this of course but your question is all about colour management, you just don't know it yet.

[Ton Frederiks]

If your applications use the same RGB color space (sRGB, Adobe RGB or …RGB) so they know what the color is defined by your RGB values and they use the same CMYK output profile, the same color engine and the same color management method, so they know how to convert your RGB to a specific CMYK for your output device and your printer can print consistantly, than you can predict what the printed result will be when you use a specific RGB value.

[CoxynotKirsty]

OK So I need to be more consistent than I was expecting. Which means dumping my HPGL2 file into Illustrator and ensuring my artwork used the same colour settings.

[jdanek · Accepted solution]

Let me see if I can help here...

"Can the file type have an effect on the printed output? Ultimately, the artwork will be in illustrator but I am hoping to send the initial RGB matrix as a PDF. The original file is actually an ASCII HPGL2 file."

- Yes.  Your file should have a profile assigned to it, which relates to your application's color settings.

Or put another way, if I print out a block of RGB colour using photoshop, will that differ from the same colour block printed from illustrator, or CoralDraw?

- Yes.  Unless all settings and profiles are the same.

Does changing the colourspace change the printed output of the file, or is it a system to stop the user selecting a colour that cannot be printed?

- Some colors are "Out -of-Gamut" in both RGB and CMYK.  Yur application typically warns you.

Obviously, RGB get translated to CMYK, but at what stage does this happen? Within the graphics program or through the driver supplied by the printer manufacturer?

- You can select somewhere in your print dialogs whether to let your application determine color or let the printer determine color.  The choices you make in the Print dialog boxes have a direct effect on how your printer driver interprets color information.  Typically, the conversions are done in the print driver.