Monitor to Print Matching

From ColorWiki

by Steve Upton

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Contents 1 Introduction 2 Lets start with lighting 3 Next, monitor calibration and profiling 4 The print profile is often a forgotten part of this 5 Setting up your system 6 Wiggle Room

Introduction

It seems that the first thing people do when they get a color printer is open the best color image they can find and print it. Then they hold the sheet up beside the monitor and wonder why they are not even close. It can be a fairly complicated issue so we decided to spend some time on it this month.

I printed my file and it does not match the screen, why?

There are many reasons why a printed file doesn't match the screen. First lets start with a quick test.

• open a white document in Photoshop and enlarge it so it covers most of your screen
• pull a blank piece of paper from your printer and hold it up beside the screen.
• see the problem?

Chances are very good that the white color of the paper does not match the white color of the screen. We call this a white point mismatch. If you do not have a match here, why would you think that putting graphics on the screen and paper would help?

Computers produce their version of white on the monitor by setting the RGB values to 255,255,255. The flavor of white can vary from a warm yellow-red color to a cool blue color. Typically we measure these colors by referring to them in kelvin degrees. 5000K is a fairly warm-looking yellowish light that is a compromise between reddish typical home-lighting and daylight. 6500K is cooler in color and looks more neutral without seeming too blue. 9300K, the color temperature at which most monitors ship from the factory is quite blueish.

Paper, on the other hand, is very dependant on the color of light illuminating it. Papers have their own color as well but nothing affects them more that the ambient light you have in your work area. In many cases your ambient light consists of a mixture of overhead fluorescent lights, daylight and perhaps desktop task lamps.

The human eye tends to see white as the basis for other colors. That is, the eye "white balances" to the paper or monitor white and all other colors fall out relative to that white. This works quickly and typically quite well. We can see graphics under many different shades of white and they pretty much look the same. Problems arise however when two different whites are placed near each other. The eye cannot adjust to both whites and so the difference between them - and the graphics displayed on them - becomes quite noticeable.

Now, back to your screen-to-print test. Chances are good that the paper looked yellowish and the screen looked blueish.

This is very important so I want to emphasize it.

If you do not setup your system so the white of the paper and the white of the monitor are as close as possible, you will not get a good screen-to-print match.

OK, sounds like a nasty problem. Can I get it to work at all?

Yes. There will always be problem colors (more below) but if you are careful, you can get a good screen-to-print match.

I should note that "match" here does not mean exact match. How close? Well, people often use terms like 90% or 95% but I have yet to see acceptable methods that numerically compare prints to screens to give these types of numbers. I am comfortable in stating that I have seen good and sometimes very good matches. The type of match that causes our customers to smile and nod their heads. To me, that's a good match.

If it's possible, then how do I go about doing it?

You need to concentrate on four areas:

• lighting
• monitor calibration and profiling
• print profile
• proper system setup and profile use

Lets start with lighting

The international standard for lighting in graphic arts is 5000K. Most lighting products you can buy are balanced to 5000K. Lighting can come in a variety of forms. Fluorescent overhead lighting, either installed in the ceiling or in hanging luminaires (light boxes), viewing booths, or task lamps. For screen matching we typically suggest small light booths with dimming capability. Setup the booth beside the screen with about a 90 degree angle between them. Dim the booth so the intensity of a white page in the booth matches the intensity of the white screen - this is surprisingly important and is the reason why we always suggest spending a little more on the dimmable booths.

Next, monitor calibration and profiling

Make sure you start with a good monitor. Good typically means you paid more than $500 for it and it is less than 2 years old. Spending money on a monitor will not hurt you here. First adjust the monitor using its built-in controls to get as close as possible to your target white point (we suggest 6500K - more about that below). The better monitors and software will allow you to fine-tune this color using the monitor's gun controls. Then calibrate and profile the monitor using a good quality monitor calibrator like the Color Vision Monitor Spyder, the X-Rite Monitor Optimizer or GretagMacbeth's new Eye-One. Make sure the profile is selected properly in the Monitors and ColorSync control panels (Mac) or associated with the monitor in the Display control panel (Windows). Photoshop looks here to find which profile to use.

The print profile is often a forgotten part of this

It is not fair to expect that an RGB file displayed on screen will match a print. The RGB file could contain many colors that cannot be printed. To get the monitor to match the print you need the monitor to be simulating the print. The only way to do that effectively is to have a good print profile for the printer (or printing process) in question. We build many of these profiles for customers in over 25 countries (so far). If you are wanting to simulate a proof then try this:

1. Gang up the CMYK target in the kit with several of your favorite CMYK test images on one 11"x17" sheet. (28cm x 43cm - A3 size).
2. Make a proof using that sheet (or send out to have one made).
3. Clip the CMYK images off the sheet and save them.
4. Send us the target to have a custom profile built. When building proofing profiles it pays to take advantage of our $10,000 equipment.
5. We will build a high quality CMYK profile and email it to you.

Setting up your system

This final piece of the puzzle is also often done incorrectly. I am going to give you directions for Photoshop 6.0 (what? you haven't upgraded yet?)

{Editor's note: The following directions are intended for CMYK workflows and are not appropriate for RGB workflows (ie: printing through a printer driver). These instructions have been updated for Photoshop CS2.}

1. Install your proofing profile onto your system.
2. select Edit:Color Settings
3. choose your CMYK profile under Working Spaces:CMYK
4. open the CMYK test images you sent off for proofing
5. place the printed proof images in your light booth
6. dim or brighten the booth until you feel the lightness matches.

You should now have a fairly close match.

If you find the blacks or paper white are still off try this:

1. Select View:Proof Setup->Custom
2. Select your proofing profile for Device to Simulate
3. Check "Preserve Color Number" <-- very important for CMYK files
4. Ignore the "Intent" setting
5. Check the "preview" box
6. While you can see your images, try selecting Paper White and/or Ink Black.
7. You can name this proofing method by clicking "save" then it will appear in the proofing menu for use later.

Paper White will attempt to simulate the white (or non-white) of the proofing stock. Sometimes this looks great, other times not.

Ink Black will simulate the grayness of the black ink as recorded in the profile. For printing processes like newsprint where 100% is a dark gray, this will lighten up the blacks on screen.

If they still don't look close, go back and try the blank-paper-beside-the-screen test. You may want to calibrate your monitor at a different white point to better match the white of your viewing booth/paper.

Wiggle Room

Or what to do when it doesn't match as well as you want.

Matching a screen to print is a pretty tough thing to do. Don't get too discouraged if it doesn't work perfectly the first time. What we are finding is that setting things up the "theoretically" correct way may not be the best way.

• White on monitor - In theory you should calibrate your monitor's white to 5000K to match a viewing booth with 5000K bulbs. In reality 5000K on screen often looks too warm / reddish. We suggest calibrating your screen to 6500K. It will give you a more pleasing white color on screen and will probably match your booth better. If your monitor calibration system allows the selection of many different white points, experiment to see which one works best. Before you get worried that this may be an unorthodox method, remember that your eye is the final judge. If the viewing booth has good quality 5000K bulbs installed and an instrument-calibrated monitor looks wrong then change the monitor's white (in the profiling software). Just because the instrument says it's OK doesn't mean you should believe it!

• Lighting - Viewing booths with fluorescent lights are not the only way to go. Ottlites are a popular task lamp which has 5000Kish lights. I don't think they have been certified for graphics arts use though so don't take them as gospel. Also Tailored Lighting has created a remarkable set of halogen lamps that can be installed in track lighting. They are the closest lighting to sunlight and don't suffer from spectral "spikes" like fluorescents do.

Editor's note:

More detail on why our eyes see white differently at different brightness levels can be found here:

https://www.solux.net/cgi-bin/tlistore/infopages/eyes-response.html

Tailored Lighting / Solux: http://www.solux.net/

Editor's note:

Solux lamps are no longer being sold in the US. The following may provide more info on how to achieve good lighting:

http://digitaldog.net/files/16TheRightLightpart2.pdf

Understand the limitations

Remember that a monitor cannot display all the colors a typical press or printer can print. Gamut differences can vary a fair amount and it can get to be a complicated topic. If you want to learn more about gamut comparing and device limitations I suggest you try our ColorThink software. One of ColorThink's main features is its ability to overlay multiple profile gamuts in 2D and 3D graphs. There is simply no better way to see if the monitor will display all your printing colors or if your inkjet printer can actually simulate the proof or press.