Tutorial 1: Read Me First.
A few words about monitors, embedded profiles, color conversions, and other areas related to color.
“I have a picture that looks good on my monitor, but…”.
People will sometimes ask me a question that begins this way. An image will look good on the person’s monitor, buy look terrible when sent to an inkjet printer, a color separator, or even another monitor. Why does this happen?
A picture on your monitor has no value if the image won’t reproduce accurately when sent to a printer, a color separator, or in the case of the Internet, another monitor. An image that only looks good on your monitor has no value to anyone else, and indicates a problem.
Creating images in the computer, or absolute vs. relative truth.
We are visual creatures by nature, so it’s easy to think that we are creating images on our monitor. Try to remember that images are actually created in the computer's RAM, and the monitor simply displays the results. You use the various tools in Photoshop to manipulate pixels and color information while the monitor displays the results. You could be spending time making an incorrect file to please a monitor that is displaying the image incorrectly. The data in the file is absolute, while your monitor is relative. Extremely relative.
Calibrate your moniter!
Most of the time the problem is that the monitor in question hasn’t been calibrated. Most uncalibrated monitors are set too bright and too contrasty. Calibrate your monitor! If you're serious about imaging, you should spend the money on a color calibration system. At the very least you can run Adobe’s calibration program that comes with Photoshop. That will get you in the ballpark. Then get in the habit of reading the color data in your file.
Going by the numbers..
Look at the color values you get from the Eye Dropper tool. This may take some practice, and an understanding of CMYK or RGB color spaces. Let’s say a part of your file is supposed to contain the color red. In CMYK printing there are two colors of ink that produce red on the printed page magenta and yellow. If you don’t have an overwhelming amount of magenta and yellow data in your file, you aren’t going to print red on press. The area may appear to be red on an incorrectly calibrated monitor, but you will be sending an incorrect file to another color device or printing house. Go by the numbers, and be sure that the correct color data is in the file the first time.
With CMYK values of 28, 98, 91 and 29, this area will print as red.
It could be more red by removing cyan and increasing magenta and yellow.
Use Embedded Color Profiles.
Have you ever opened a file in Photoshop and gotten a message that the embedded color profile doesn’t match the current working space? A lot of people don’t know what that means, or what to do about it. Here is a brief description of the situation:
Right now your copy of Photoshop is using color profiles for the RGB and CMYK working spaces, and you may not even know it. The two I use are Adobe RGB 1998 (for RGB) and U.S. Coated SWOP V2 (for CMYK). These are generally considered by color experts to be the current best color spaces, and both Mac and PC users should set Photoshop to use them. When I create a CMYK file to be printed on a press, I’d like to think that the person running the press is printing the exact color I gave in my file. When saving a job, I’ll embed my working color space into the file, and I’ll write down that color space on the CD I send out. When the file gets where it needs to be, the printer will hopefully use my embedded color profile. If not, the color may shift to that computer’s current profile, and I wouldn’t be responsible for the resulting problem with the printing. I’ve had people call me to say they weren’t happy with a proof they received from their printer. This has always happened because someone opened my file, didn’t read the color profile mismatch warning, and shifted my file into their current working space. Embed your color profile when saving your job. It will save you.
Make sure to embed a color profile before the file leaves your computer.
Get a proof made.
OK, we've calibrated our monitors, we used the Eye Dropper tool to get a feel for what color is contained in the file, and we saved a CMYK file with our embedded color profile (of course you can also embed a profile in an RGB file). How do we know exactly what the file will look like when printed? Get a proof made. Sending the file to your ink jet printer is not the same as getting a proof made because ink jet printers don’t use the same technology as a printing press. Send the file to a professional separator and ask for a “dot generated, pre-press, wet proof”. This is going to cost some money, but don’t you want to know how something will look once before it gets printed incorrectly 1,000,000 times? Some digital proofing systems can produce proofs that are amazingly close to the quality of wet proofing systems at a fraction of the cost, so talk to the separator about your proofing options, but get a proof made. I know a color expert who, when dealing with a printing company he has never printed with before, will ask the employees, “How closely does your proofing match your printing, and how can you prove it to me?”.
RGB vs. CMYK, or When Worlds Collide.
Maybe nothing has caused more problems in the world of digital imaging then the difference between these two color spaces. Why is that, what are they, and why aren’t they friends?
RGB The color technology used by a devise where Red, Green and Blue are the primary colors. Television, computer monitors, digital cameras, and photographic film are RGB. Look at the color channels in Photoshop of a file that is RGB and you will see that it is made up of three colors. Every pixel in a channel can rage in digital value from 0 to 255. It should be noted that most color ink jet printers will print an RBG file better then a CMYK file.
CMYK The color technology used by a devise where Yellow, Magenta, Cyan and Black are the primary colors. Black was given the initial K because old-timers used to refer to black as the key color the color used for trapping, etc. A color printing press will take paper into the press, and the combination of yellow, magenta, cyan and black ink, in that order, will give the amazing illusion of a full color image. Create a CMYK file in Photoshop and look at the channels. Every pixel in a channel will have a digital value between 0 to 100.
The difference between the two spaces is the cause for the dreaded RGB to CMYK conversion - the terrible shift in color you sometimes see on screen when converting an RGB file to CMYK. RGB is simply a larger color space than CMYK. When you make the change from RGB to CMYK, you a trying to shoehorn a larger color space into a smaller one, and information can be clipped (RGB’s 3 x 256 has more information than CMYK’s 4 x 100). Photoshop’s Selective Color tool, or the Saturation tool can help get the illusion of the original luster back. For example, if you lost some green color after the conversion, use the Selective Color tool to add yellow and cyan to green. Avoid doing the conversion in front of your client because you don’t want them to see their job die on screen.
In this shot, I'm increasing cyan and yellow to green.
If you have never used the Selective Color tool before,
you will probably love it after five minutes.
The myth of the same monitor.
Sometimes people mention that they are having difficulty getting the same results from two monitors that happen to be the exact same model. Here are some things to consider:
1) Two different monitors that are the same model and from the same manufacturer are still two different monitors.
2) Take a monitor and calibrate it. If the lights in the room are on, turn them off. The image on the monitor will look different. If you work in a room with the lights out, turn them on and the image will look washed out.
3) Take two calibrated monitors and put them in different parts of the room. The ambient light in the room could cause the same image on both monitors to appear different when you glance between them.
4) Take two calibrated monitors and attach one to a Mac and one to a PC. Chances are that the same image on both computers will appear darker on the PC, so run Adobe’s color calibrator.
5) Different programs will display the same image on the same computer and monitor differently. This has been noted by people who use Quark and Photoshop simultaneously. While Photoshop will display the image more realistically than Quark, you should get a pre-press proof made to see what the final output will look like.
Copyright © 2010, David Phillips. All rights reserved.
No part of this document may be reproduced without permission from the author.