RGB to CMYK...HELP !!! 1

[SonicMax]

People,

For all the photo images I used for a 16 page Insert Booklet design for my upcoming CD release (which started out their life as RGB’s), I used Photoshop 6 for processing (processing RGB's as RGB's, as Photoshop recommends)...& then I converted them to CMYK (also in Photoshop 6.) Then I placed these converted images into the Adobe Illustrator (10) design templates provided by the replication service, finalized everything; & sent them off.

Today I got the proofs back from their print division; & all graphic content is DARK & GREEN !!!

I contacted the graphic arts dept. at the replication service; & they told me they could color correct them at their end, based on the color prints I sent them…but when I learned the cost…I thought it might be best to just do it at my end.

1) First of all…what happened? The photos looked great in both Photoshop & Illustrator on my monitor as RGB’s. When I had converted in Photoshop, there was no difference at all in appearance. My working spaces in Photoshop are all default; & the photos look just like they do on my monitor when they print out in my project studio (on a typical HP Ink Jet.) I don’t mess around with Adobe Gamma or calibrating my monitor…so, I don’t get it.

2) How can I fix this problem? Is this common? Is there some other way to go back & convert the RGB’s, or is there some criteria I can use to color correct them in their present state as CMYK’s? It’s very frustrating…all I want is for them to look like they do on my monitor & as printed by my printer. Now…I have to put the graphics portion of my CD on hold while this is getting sorted out…which pushes back my release date.

Will be appreciative of any help,

Sonic Max

 

[GraphicsTutor]

Sonic Max

You need to re-convert all of your images. But before you do, go to the Color Settings (command/control-shift-K). With the pull-down menu, change to U.S. Prepress Defaults. Photoshop has many different ways of converting RGB to CMYK, most of which don't look very good in print. U.S. Prepress Defaults are the standards of the printing industry. Start from the original images. Don't try to go from the existing conversions back to RGB to CMYK. It will only make matters worse.

Images in print will never look never look like your monitor. A monitor screen creates color from light, ink on paper is reflective. They will never match. That is why the printer is showing you a proof of what the printed piece will look like. You could invest in expensive color-calibration hardware and software and it will get closer, but it will never be exact. Printers control color by the numbers (the Info palette) because they know they can't reproduce what they see on screen.

Good Luck

 

[duncdude]

Sorry graphicstutor - I don't agree

Modern monitors do a very good job of emulating what the picture will look like in print. Photoshop can show colours out of gamut and handle simulated dot-gains to muddy up pictures on screen to represent how the image should darken when on press. Modern monitors will show a 1% black on a white page - and it is possible to see the difference between 98% / 99% & solid black. I have been high-end scanning and retouching for 17 years and never experienced any great difficulties

However i can't explain what is going on with Sonic Max's pictures...


Kind Regards
Duncan

 

[GraphicsTutor]

All

I know that opinions differ out there, but I have been a prepress opertor for the last nine years (now doing training). Prepress departments are the people who take the designer's files and make them work on press. RGB is created from light, CMYK is created from ink. Exact matches are not possible. Why else would prepress houses and quality printers insist on a client signing off on expensive Matchprints or Epson proofs? It is because no prepress person worth their salt will trust what they see. They only trust the numbers. They are not going to guarantee color on a customer's monitor they have never seen when they don't even trust their own monitors. Most presses are also now printing by number. They only trust the readings from the densitometer. Lighting, wall colors, desktop patterns, and tiredness all affect the way we perceive color. Also, your desktop inkjet is more saturated and brighter than you will see on your Matchprint or press run.

Sorry if this only creates more disagreement. I am also a mac person. If you want a real heated discussion, there's a topic for you.

The Graphics Tutor

 

[BodesMan]

I also work in Prepress and the operators in my company's color dept. always go by the numbers - they never judge color on their monitors. They will look at proofs to review their color moves - never the monitor.

Thats the guys that work here, there could be other operators out there that do use the monitor for reviewing color instead of proofs and numbers.


info@prepress-online.com

http://www.prepress-online.com

"Tell'em we're comin', and hell's comin' with us.

 

[kiddpete]

Correction of color problems does not bode well when you say 'I don’t mess around with Adobe Gamma or calibrating my monitor…so, I don’t get it.'. If your monitor is not calibrated, then you don't know what your images really look like. It's the same with your printer, if you are not using the correct color profile for the printer/paper combination, then you still don't know what the images look like. Your printer could be just as far off as your monitor is.

Bottom line: if you want to color match, you will have to calibrate your monitor, and use the correct color profiles for your printer and paper. You may also want to look at how one is supposed to print images with Photoshop via a color managed work flow.

 

[SonicMax]

graphicstutor,

Thanks very much...switched to that setting; & conversion to CMYK is now right on the money. As to re-conversion...some of the originals I have...some I don't...so...I will have to perform some color correction.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


kidpete,

Stay with me, here...

I take a digital photo; & upload it into my little ol’ Wintel PC...a “Dell”, if you will.

The colors look exactly like they do in real life...I recognize this because I just took the photo.

I print that photo on my rinky-dink little ink jet printer; & the colors look exactly like they do in real life...I recognize this because I just took the photo & viewed it on my system.

At this point...my system is not misrepresenting anything...it's giving me just what I have...true to life colors. It is not giving me a "false picture" of any sort.

So I convert this photo to CMYK, place it in a design template & send it off for commercial printing...the proof comes back DARK & GREEN.

So now...the pro-industry design boys are telling me it's my fault, because I'm not a professional; & I don't have my monitor calibrated to match the archaic, dinosaur 4-color commercial printing system.

IT'S NOT MY MONITOR'S FAULT...IT'S THE FAULT OF THE DOGGONE RGB TO CMYK CONVERSION PROCESS !!! It doesn't convert to that so-called commercial standard.

So now...I take the advice of the "design professional"...& I calibrate my monitor to match the output of the stupid commercial printing industry.

And now what???...now every damn graphic image on my system is too dark & too green ???...so I go through every single image & make them look like real life colors...WHEN I HAD THAT IN THE FIRST PLACE ?

I don't see the logic.

(But thanks for the insight, anyway...not mad at you...just at the backwards system.)

Thanks all,

Sonic Max

 

[jimoblak]

Nothing is backwards. The moment that you can show us a printing method that works with light instead of ink, I'll switch to the 'future'.

Your personal HP inkjet printer is printing with CMYK inks just like the commercial printer. However, they are using different kinds of ink and different paper. This is why professionals rely on color calibration and profiles to approximate the entirely different color model that you see on your monitor. It is simply a miracle that you think the HP inkjet output matches your screen display. It is simply not possible for those colors to match perfectly.

You may also investigate the color mode of your Illustrator documents.

...and of course, there is the possibility that the printer simply messed up. Seeing that you do not work with color profiles, I would start looking at your system first.

- - I hope this helps - -
_{(Complain to someone else if it doesn't)}

 

[GraphicsTutor]

Just a little clarification. The human eye can see umpteen millions of colors with extremely subtle variations. RGB (color made from light) can reproduce perhaps a quarter of that. CMYK (color made from ink) can only reproduce a third of RGB. Printing presses cannot print continuous tone variations, it relies on converting tone to halftone dots, one more complication that makes offset and web printing a challenge that monitors and inkjets don't have to deal with.

 

[duncdude]

Hi GraphicsTutor

Can you explain what you mean by

a challenge ... inkjets don't have to deal with

i.e. What difference is there between the way an inkjet prints and a printing press?


Kind Regards
Duncan

 

[duncdude]

SonicMax

I reckon that jimoblak's suggestion of checking Illustrator's colour settings could be the problem


Kind Regards
Duncan

 

[GraphicsTutor]

duncdude

Sorry, I've been busy and forgot to check back with this.

If you get a magnifying glass and look at the dots on a printed piece, say a book cover. You will see cyan dots, magenta dots, yellow dots and black dots, overlaid on 15 degree, 75 degree, 45 degree and 90 degree angles, respectively. The inks are semi-transparent and form a pattern known as a "rosette". The rosette is one of many moire patterns (the least problematic one) formed by overlaying screens on one another. The inks on the press adhere to the dots. Ink is known as substractive color, you subtract color to get white. RGB is additive color, you add to get white.

Inkjets use inks that are manufactured to be brighter and are printed in a continuous tone like a film photograph, no dots. Inkjets also use more ink to get the same color. On a press, black is used for black type. An inkjet uses all four colors to make black. If your black ink cartridge is empty, you will see type in magenta, cyan and yellow. That's also why your color ink runs out also when you print a lot of text. Since the inkjet doesn't have dots and screens and uses more ink and brighter ink to achieve the colors, it will be brighter, sharper and more pleasing to the eye.

Hope this helps
Pam

 

[duncdude]

Hi GraphicsTutor

Thank you for your reply. I am quite well versed in the repro field - i've owned two repro comanies & have owned all sorts of equipment from imagesetters to Dupont Cromalin machines to drum scanners. It is for this reason i am in complete agreement with you regarding print.

Where i cannot agree with you - not for one moment - is with inkjet technology. Sorry. I just don't understand how you think they print! The only printer i have ever used that prints continuous tone is dye-sublimation technology. Inkjets squirt ink at the paper - the dots are just getting smaller. In fact they are measured in picolitres. I could, however, be a little unsure of how they have progressed. However, i was not aware they they "didn't have dots"!?


Kind Regards
Duncan

 

[duncdude]

Since the inkjet doesn't have dots ...

I'm sorry GraphicsTutor - but you are going to have a hell of a time trying to convince me!

This is a page of 43 inkjets output at 30x magnification:-

http://www.silverace.com/dottyspotty/issue3.jpg

... I'm not having a dig. It's just that many people may read this post - then they all go off with misconceptions about print. I've heard many people convinced that printing is done in RGB, for example - and many other ridiculous things. It is very important not to post such information unless we are SURE we know what we are talking about


Kind Regards
Duncan

 

[jimoblak]

The comment about not having dots may refer to the fact that paper absorbs the inkjet printer's dots and can often make a color blend within the substrate of the paper. But there are still 'dots'. Even dye-sublimation uses dots. But now we are nitpicking little tiny dots.

- - I hope this helps - -
_{(Complain to someone else if it doesn't)}

 

[jimoblak]

Since the inkjet doesn't have dots and screens and uses more ink and brighter ink to achieve the colors, it will be brighter, sharper and more pleasing to the eye.

This might be more to the point...

"Since the inkjet doesn't have easily viewed dots and coarse screens..."

- - I hope this helps - -
_{(Complain to someone else if it doesn't)}

 

[signal49]

I'm so happy to read about this topic. I work in a small print shop and I always get customers who bring in a crappy printout of a 72 dpi image, usually their logo, that they want to enlarge for a brochure or something. It's so hard when I ask for a better resolution file... they say "Well my printout looks fine, why can't you use this?" I can't really explain that their cheap inkjet prints "better" than an offset press or digital copier because it blurs and gets absorbed into the paper more... But I may just print this thread and keep it on hand!

Wish I had some answers for the original RBG > CMYK issue... does sound like changing the color setting to US Prepress did the trick!