Color Management: Calibration and Profiling

Introduction

Welcome to the second post in our color management series. Be sure to check out Part One if you haven’t already done so. Today we’re going to talk about the importance of calibrating and profiling your input & output devices in your color management workflow. This is probably the most important step in the color management process, especially calibrating and profiling your monitor display because you need to trust that the color you see on your monitor is true and correct in order for you to be able to make color and luminosity decisions.

Profiling the display

When we’re looking at a photo, or anything for that matter, on our monitor display, we’re basically looking at a huge number of pixels, each of which displays a certain color. Monitors (or those pixels to be more precise) don’t always display the color they are supposed to display correctly because there are usually some modifications occurring between what color info the program (let’s say Adobe Photoshop or Illustrator) is sending out to the monitor to display and what the monitor does actually display.

Furthermore, the monitor display changes the way it interprets color information overtime, so you need to constantly tune your monitor to display color correctly, and this is when calibration and profiling of the monitor display comes into place.

Profiling the display has two parts to it. First of all, you have to have what is called a profiling software. The profiling software takes color information from your computer and sends it off to your monitor display. Second, you have to have a spectrophotometer (also called a colorimeter). The spectrophotometer is a device that is attached to your CRT monitor screen using rubber suckers, or hung over the edge of your LCD screen resting delicately against the surface of the screen.

What the spectrophotometer does is that it reads the color info that is actually being displayed on the monitor screen, and sends that info back to the profiling software so that the profiling software can make its measurements and map the color your monitor displays to the color info your computer sends for it to actually display, insuring that what you see on your screen is the color you’re actually intended to see, instead of the color your monitor thinks you should see.

This being said, this process is creating a profile for your monitor that will always work as a link between your computer and your display to make sure the screen is displaying the right color it’s being told by your computer to display.

A calibration/profiling package I am familiar with is the Gretag Macbeth that comes with the X-Rite Eye-One Match 3 profiling software, but I’ve also heard of other monitor profiling packages such as the basICColor Display and Squid combination, the Monaco Optix XR system, and the ColorVision Monitor Spyder and Spyder2Pro Studio.

When you get the Gretag Macbeth package, you simply install the software that comes on a CD with it first. You then start the X-Rite Eye-One profiling software and follow the wizard. It will first ask you to hook up the calibrating device to your computer through a USB port. After you do that the wizard will ask you what device you wish to profile since this system can offer profiling of a monitor display, a projector, a scanner, a printer, and a digital camera with its accompanying spectrophotometer.

After you choose to profile a monitor display, you will have to specify what type of monitor it is. An LCD, a CRT, or a laptop monitor.

The wizard will then ask you to hang the spectrophotometer over the edge of your screen resting it nicely up against the display using a counter weight.

You will then sit back until the profiling software does its thing. It will show you the progress through a progress bar, and when done it’ll ask you when you want it to remind you to run the calibration and profiling process again. I prefer you choose to be reminded once every 4 weeks to ensure your monitor profile stays fine-tuned and up-to-date. The process is so easy and straight forward so don’t panic if you haven’t done this before, the wizard is explanatory and will guide you through every step of the way (and I’ve already done so above anyway).

Please note that if you get the X-Rite Eye-One Match 2, you will only be able to profile your monitor since it doesn’t offer profiling of the other 4 devices that the X-Rite Eye-One Match 3 software does. Another note is, always use a calibration device that hangs over the edge of your screen if you’re calibrating an LCD monitor because the rubber suckers might damage the delicate surface of your LCD screen.

Profiling the input

In the profiling input process you can choose to profile your digital camera and/or your scanner. Profiling the camera input is a tricky process since light conditions can vary from time to time and from one place to another, so unless it is fatally critical that your whole workflow is profiled from start to finish, you need not bother about profiling your camera input.  Unless you do all your shooting in let’s say a studio with one specific lighting system that never changes at any given time, you will need to photograph a color checker chart, and take measurements off of it every time light conditions changes so as to keep your digital camera correctly profiled.

Above is how one picture can look under 3 different light conditions. As you can see, the camera’s sensor responds differently to colors and white balance changes drastically from one light condition to another. So I wouldn’t stress on profiling your digital camera’s input. The most important thing for you to be able to trust what you see on your computer screen.

As far as scanner profiling goes, you will need to scan a film or print target similar to the one in the image below, and then use a profile creation software such as the Gretag MacBeth Profile Maker to read the data, make measurements, and build a custom profile of your scanner based on the readings taken from the scanned target. You can then incorporate your scanner characteristics into Adobe Photoshop by selecting the profile made of your scanner once you open a scanned image in Photoshop.

Profiling the output

For achieving the best printout results, you need to set up a separate profile for your printer along with each media paper type you intend to use it with in your work. When you purchase a printer and install the driver that comes on a CD along with it, the installation process creates a number of profiles for your printer and a few brand media paper combinations. This will be OK for a start, but I do prefer you run a custom profiling process for your printer along with each media paper type using the Gretag MacBeth Eye-One spectrophotometer.

To do that you will need to make a print of a test target like the one previously shown above, and you need to do this with each paper type you intend to use with your printer. You will do this print test without color managing your printer. Let the printouts settle till the next day, and then use every test target print to make a custom profile for each media paper/printer combination.

Conclusion

In digital imaging, color management is the controlled conversion of color representation between the various digital devices involved in a workflow. This includes digital cameras, computer monitor screens, scanners, printers… etc. The goal is to measure and adjust those devices in a way that insures they represent colors in the same way and that they represent them right.

By now you should be familiar with the basics of color management. Next, we’re going to walk you through the process of configuring Adobe Photoshop color settings for various Photoshop workflows. Stay tuned…

Color Management in Adobe Photoshop

This is the first part of a comprehensive detailed series of posts guiding you through the image editing process step by step from profiling your display and managing your color space and settings, to profiling your printer and preparing your work for print, to saving and distributing your work on the web.

The primary purpose of profiled color management is to achieve a good match of an image color between all devices involved in an image editing workflow, such as the camera display, the computer screen, and the printer.

Part One: Color Spaces

In Photoshop, the color management process begins with reading the profiled RGB color space of an image, and converting that to the current Photoshop RGB working space if it was using a different one. While editing a photo, the RGB workspace used in Photoshop is immediately converted to that of your monitor display so you’d be able to view the colors correctly. And similarly, when you print out your images, the RGB workspace is converted to that of the printer, or an RGB to CMYK color conversion of a known printer profile takes place.

Thus, being aware of your color space is a very important aspect, especially if you intend for your work to be distributed through digital or print media. If you’re spending all your time and energy making sure your images look good, might as well invest a little time and go the extra mile to ensure they look good to others as well.

An image that looks like the above in Photoshop, would look similar to the image below in printout if sent straight to the printer without any kind of color management

Choosing an RGB work space

In order to make up your mind on which RGB color space you should use, I’m going to give you a brief description explaining the difference between various color spaces. Rule of thumb though, it is better to stick to your decided workspace throughout your work.

So let’s take a look at the different, most popular RGB color spaces:

sRGB

sRGB reflects the characteristics of the average PC monitor. This standard space is endorsed by many hardware and software manufacturers, and is becoming the default color space for many scanners, low-end printers, and software applications. Ideal space for web work, but not recommended for prepress print out work because of its limited color gamut which causes color clipping when converted to CMYK.

Adobe RGB (1998)

Adobe RGB (1998) was developed by Adobe Systems. It is a fairly large gamut (range of RGB colors) that covers most of the CMYK color space, but by using RGB colors on devices such as computer monitors. It is a popular color space to go with for printing and reproduction since it offers a suitable RGB to CMYK conversion.

ProPhoto RGB

ProPhoto RGB space has the advantage of preserving the full gamut of raw images when converting to RGB, and providing better tonal separation than most other RGB color spaces. This color space is particularly suited for output devices such as digital dye sub and inkjet photo printers, and for applications such as HiFi color. ProPhoto RGB is also called “ROMM RGB”.

Apple RGB

Apple RGB Reflects the characteristics of the average MAC OS monitor, and is used by a variety of desktop publishing applications, including Adobe Photoshop 4.0 and earlier since it was the same as the monitor’s color space. Use this space for files you plan to display on MAC OS monitors or for working with desktop legacy application files.

In general, a good thing to keep in mind is that large color gamut or space lead to posterization, which is the conversion of a continuous gradation of tones to several regions of fewer tones, with abrupt changes from one tone to another. Whereas small color gamut lead to clipping, which is blown-out highlights or dark areas in an image.

In Adobe Photoshop you can change your working RGB color space from the Edit menu >> Color Settings >> Working Spaces >> RGB as illustrated below:

Conclusion

Different digital devices have different output characteristics, and unless you tune your work to match those of your destination media you’re most likely to end up with an endless number of versions of your same piece of work most, if not all, of which look nothing like you intended it to be.

To insure homogeneity of your work, you should initially decide on a color space that best suits your needs depending on publishing and distribution means of your work, and go with that.

The next step — and probably the most important one — in the color management chain would be calibrating and profiling your input and output devices.

We’ll guide you through that in the next post in this series. Please stay tuned…