September 23, 2014, 12:38:57 AM

Author Topic: CMYK Improvements  (Read 3587 times)

unfocused

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2109
    • View Profile
    • Unfocused: A photo website
CMYK Improvements
« on: November 21, 2011, 05:33:17 PM »
Anyone out there have any experience with CMYK?

I'm working on a photo book and I'm a little stunned at how much is lost converting from RGB to CMYK. Color shifts, dull colors, etc. I'm not expecting an image to "pop" quite like it does on a screen or a tablet, but losing all the brilliance in certain colors (reds, yellows and greens particularly) is more than a little frustrating.

Some of the images rely heavily on color and tone contrasts to work and the images lose way to much in the conversions.

I've had a little luck adding adjustment layers after converting to CMYK, but that seems to introduce an entirely new set of challenges. I've found no decent reference books. Eventually, the book will go to a professional printer to tweak the images, but in the meantime, I need to produce a good sample to pitch the project.
pictures sharp. life not so much. www.unfocusedmg.com

canon rumors FORUM

CMYK Improvements
« on: November 21, 2011, 05:33:17 PM »

neuroanatomist

  • CR GEEK
  • ********
  • Posts: 14465
    • View Profile
Re: CMYK Improvements
« Reply #1 on: November 22, 2011, 10:32:33 AM »
RGB 2 CMYK = WYSINWYG.  Dont'cha love all these abbraviations? 

Fundamentally, RGB and CMYK are quite different, since the former is based on adding color to black whereas the latter is based on subtracting color from white. 

Actually working with a CMYK image on an RGB monitor is not optimal, since you're using an additive color display to simulate what will be a subtractive color print output.   The CMYK gamut is much smaller than the RGB gamut, and also oriented differently:



When you print your RGB image at home, the print driver is converting to CMYK for you.  A photo lab also converts it to CMYK, using a standard profile conversion based on the sRGB color space.  In a truly color-managed workflow, where you have control over the image and the printer, you'd want to calibrate both to the same standard (which is where a tool like ColorMunki comes into play - a spectrophotometer that you use to measure the same image on your display and a print, which then generates a monitor profile to correspond to the printed output - then, WYSIWYG).   Of course, with an image for publication, it's not your printer...and that makes a difference.  Your printer is likely an inkjet, whereas a publication will be printed using offset lithography, i.e. halftone screens at different angles for each of the four colors.

I'd recommend converting to CMYK as a final step in the workflow, and the make adjustments based on a printed proof.   

Commercial printers want you to submit files as CMYK primarily to avoid the responsibility of color shift surprises in the conversion - i.e. so if it doesn't look right to you at the proof, you have to bear the cost of the adjustments. 

In the past, the images I submitted for scientific publication needed to be CMYK (TIF or EPS).  More recently, many of them have been accepting (and a couple even preferring) an RGB image with an associated ICC profile.
« Last Edit: November 22, 2011, 10:34:21 AM by neuroanatomist »
EOS 1D X, EOS M, and lots of lenses
______________________________
Flickr | TDP Profile/Gear List

unfocused

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2109
    • View Profile
    • Unfocused: A photo website
Re: CMYK Improvements
« Reply #2 on: November 22, 2011, 03:00:10 PM »
Yes. But my question isn't why it happens. It's what to do about it.

When a brilliant red drops down to a dull scarlet or a bright orange to a near brown, I want to bring back some of the color. I know I have to work within the limits of the printed page. I've been involved in print of some form or another for 40 years, so I'm aware of the limitations. But some of the color shifts go beyond the drop in brilliance that you expect going from RGB to CMYK. And, it's not consistent. Some images show only minimal changes, on others it is major.

I need to squeeze every last bit of brilliance out of my images, so that when I pitch the project to people who will help me raise the money the pictures knock their socks off.
pictures sharp. life not so much. www.unfocusedmg.com

neuroanatomist

  • CR GEEK
  • ********
  • Posts: 14465
    • View Profile
Re: CMYK Improvements
« Reply #3 on: November 22, 2011, 03:14:35 PM »
You might need to find a printing service that does spot color or Pantone printing.
EOS 1D X, EOS M, and lots of lenses
______________________________
Flickr | TDP Profile/Gear List

awinphoto

  • 1D X
  • *******
  • Posts: 1994
    • View Profile
    • AW Photography
Re: CMYK Improvements
« Reply #4 on: November 22, 2011, 03:39:49 PM »
My photography gets printed at commercial printers monthly for companies I shoot with... Sadly there is not much you can do... Neons, vibrant blues, some greens all will get clipped pretty bad... Red's and yellows aren't as noticeable... You can ask commercial printers (for a fee) to add spot colors or an additional ink to the print press if you have a specific color you want to nail, however if you are printing a photobook in short runs, odd's are most likely no.  I'm waiting patiently for commercial printers to catch CMYK up with other color gamuts. 
Canon 5d III, Canon 24-105L, Canon 17-40L, Canon 70-200 F4L, Canon 100L 2.8, 430EX 2's and a lot of bumps along the road to get to where I am.

MikeD

  • Guest
Re: CMYK Improvements
« Reply #5 on: November 24, 2011, 08:29:31 AM »
It's true that CMYK is very limited, but there are a few things you can do to end up with a pleasing print project:

• It's crucial that your monitor is recently calibrated and profiled, using a hardware device.
• Make sure Photoshop color settings are set to convert using CoatedGRACoL2006.icc (if printing in U.S.) with Relative Colorimetric & Black Point Compensation as good general settings
• Don't view the image in RGB (except perhaps momentarily to check something, etc)
• Set your Photoshop to at least be viewing your RGB image as CMYK with View—>Proof setup—>Working CMYK. If you can "handle the truth" you can go further using the soft-proofing settings that show simulte paper color.
• You can make several custom Proof settings to show what your image will look like using different rendering intents (mainly Relative Colorimetric and Perceptual) and then you can convert using the best choice for that image.
• Looking at the out-of-gamut (OOG) areas of color in the image, try de-saturating any problematic OOG colors enough to bring back needed detail. Some clipping can be acceptable. Relative Colorimetric intent will simply clip outside colors, and Perceptual will try to bring all colors into gamut but often at the expense of all colors.

The secret lies mainly in "lowered expectations" which can also be a beneficial in other areas of your life.

I'm not a photographer or designer. I founded online service Colorprep http://www.rgbcmyk.net in 2003 and work alone prepping print images full-time for a group of quality-oriented graphic designers, photographers and printing companies across the U.S. Feel free to contact me for more info or if you'd like to send me a typical image to see how I would handle it.

Mike

unfocused

  • Canon EF 300mm f/2.8L IS II
  • *******
  • Posts: 2109
    • View Profile
    • Unfocused: A photo website
Re: CMYK Improvements
« Reply #6 on: November 24, 2011, 07:09:09 PM »
Mike, thanks. These are the kind of tips I was looking for. I'll try your recommendations. But be careful, I may take you up on your offer as well.
pictures sharp. life not so much. www.unfocusedmg.com

canon rumors FORUM

Re: CMYK Improvements
« Reply #6 on: November 24, 2011, 07:09:09 PM »

stefsan

  • Rebel T5i
  • ****
  • Posts: 116
    • View Profile
    • flickr
Re: CMYK Improvements
« Reply #7 on: December 07, 2011, 08:01:55 AM »
One thing I like about blurb.com is their knowledge base: try http://www.blurb.com/resources/color_management for a rather good introduction.
« Last Edit: December 10, 2011, 03:44:34 PM by stefsan »
EOS 7D; EOS 40D; EF 70-200 f4 L; EF 70-300 L; EF 100 f2.8; EF-S 15-85; EF-S 10-22 |
http://www.flickr.com/photos/stefsan/

canon rumors FORUM

Re: CMYK Improvements
« Reply #7 on: December 07, 2011, 08:01:55 AM »