CMYK Value from RGB - DPChallenge Forums

09/13/2005 10:11:19 PM · #1

Hey everyone,

I have a really bad problem i need fixing fast and i can't figure it out.

I have this RGB color (Blue). Value: 6, 28, 229 (061CE5) i want printed. THe problem is, i can't get anywhere Near this color value in CMYK... which in turn, stops me from printing the proper blue.

Anyone has any suggestion or a way to calculat/find the right CMYK value?

The RGB value is 'purple' in CMYK. its driving me nuts.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/13/2005 10:17:00 PM · #2

There are many colors which simply cannot be reproduced in CMYK.

Your monitor in 24-bit RGB mode has a gamut of about 16.7 million colors, of which the average human can distinguish something like 5-10 million.

The color gamut of CMYK mode is about 7000 colors -- somethings gotta go, and it's usually the bright blues, reds, and purples.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/13/2005 10:19:00 PM · #3

Your best bet to get close is probably to convert to CMYK mode (in Photoshop) and use an Adjustment Layer with "Selective Color" to try and tweak the colors closer to what you want.

Canon RF 24-70mm f/2.8 L IS

09/13/2005 10:22:00 PM · #4

Oh! that could work!! I'll give it a try! Thanks General!

kirbic

Canon EOS R5

09/13/2005 10:23:19 PM · #5

Boy, I just tried that one out, and it is a rather rude shift. The closest I get when assigning a CMYK profile to one swatch and comparing to another is using "relative colorimetric" intent with black point compensation unchecked. It's still a rather striking change.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/13/2005 10:24:15 PM · #6

You're welcome! Good luck -- maybe when you're done, you can post some before/after examples for other people to learn from.

09/13/2005 10:34:42 PM · #7

Actually, that's a good idea. This might give you guys a good idea of my problem as well.

Here's the result i want (that's in RGB):

And that's the equivalent in CMYK, tweaked with a selective color adjustment layer:

Now what i'll do is try to find a completly different blue in CMYK (one that fits what i want) and try to tweak it with a selective color adj. layer, see what gives.

Note that i censured parts of the images for my client's confidenciality.

Message edited by author 2005-09-13 22:38:02.

th3ph17

09/13/2005 10:45:33 PM · #8

cmyk is a brutal and depressing color space. How are you printing this image?

Message edited by author 2005-09-13 22:45:46.

Canon EF-S 18-55mm f/3.5-5.6

09/13/2005 10:57:30 PM · #9

Its for business cards.
I'm told it has to be done in CMYK.

The beef i got with all this is, although in RGB, the end product is EXACTLY what my client wants... it cannot be printed. Everytime i try it, it looks like shit, washed out, purple... anything else then what its supposed to.

Simonjw

Canon EOS-30D

09/13/2005 11:19:35 PM · #10

If its being printed offset, the alternative could be to select a spot colour and create your image using a duotone.

Edit: For those who are interested, here is a diagram that represents the gamuts for CMYK and RGB.

If you need any help, feel free to PM me, i'd be glad to see how i can help out.

Kind regards,
Simon

Message edited by author 2005-09-13 23:24:42.

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

09/13/2005 11:30:16 PM · #11

CMYK is a colorspace that is designed to reflect the conventional printing process of layering 4 colored inks to rpduce a full-color image. There's NO way 4-color printing in CMYK can produce the luminosity you have in your RGB example. I'd guess that the CMYK version fairly accurately shows what's possible in 4-color process printing.

You can print directly from digital, RGB files in commercial laser/inkjet printing and while this may get closer to what you want it will never match the sheer luminous quality of the projected image you see on your screen.

The spot color option is also a good one, but again that won't look as luminous as what you see on the screen.

R.

Edit to add: inkjet (or dye) printing of the business cards combined with a glossy lamination might be the closest you can get.

Message edited by author 2005-09-13 23:31:16.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/13/2005 11:44:47 PM · #12

You can make photographic cards. You can fit 3 cards on a 4x6 print, which will cost anywhere from $0.10 to 0.29 -- you'll just have to figure out a way to hand cut them. It's also a good way to try out a design without investing in a full print run.

09/14/2005 12:59:51 AM · #13

That's a good idea... although it is also a problem, as my client wants informations and design on 'both' sides of the card...