Color Systems & Color Spaces

Understanding RGB vs. CMYK vs. CMY

The primary colors of light RGB (Red, Green, and Blue), represent a visual range that, in theory, can produce any color that can be seen by the human eye. Mixing with light is an additive process. (When you add all the colors together, they make white.)

Printing is a subtractive color process and uses the opposite colors, CMY (Cyan, Magenta, and Yellow) to mix and produce an image. Working with physical colors (i.e. dyes, pigments, inks) brings with it the limitations of your materials. In theory, cyan, magenta and yellow, all together should produce black. But in reality, the pigment usually turns to a muddy, inconsistent brownish-black. (The shade of brownish-black is dependent on your materials.)

This is why Black (or K for Key) is added in addition to the CMY gray-blend, giving you a sharper, richer, darker black.

So, when you are printing in CMYK, about half of your grays and blacks are made with an even blend of CMY, and the other half is a layer of black printed on top. In theory, all of your CMY channels should have the same information as your black channels, just at a lighter value.

Overall, subtractive color spaces tend to have a wider spectrum of colors to offer. This is why most people work in an RGB color space such as Adobe RGB 1998 or ProPhoto RGB, instead of CMYK. Side note: All screens use additive color.

What is a Color System?

A color system is a set of colors that represent a specific visual spectrum.* These few colors are mixed together to create a limited usable range, and that range is called a color system. Examples of a color system include RGB, CMYK, and Lab.

* “Appendix A.” Understanding Digital Photography, by Joseph A. Ippolito, Thomson/Delmar Learning, 2003, p. 372.

What is a Channel?

Photoshop organizes your chosen set of colors (e.g. RGB or CMYK) into channels, dividing up your image information by color. For RGB and CMYK, Photoshop also includes a composite channel. Each channel is in grayscale and uses a mask to store each color’s information. You can edit this mask to alter the look of your image and how the channels are mixed.

In RGB and CMYK, you can use the Channel Mixer to change the amount of color information on each channel.

What is a Spot Color?

An additional color that is not a part of an established color system or mode.

For More Information

Linkedin Learning: Understanding CMYK vs. RGB
Linkedin Learning: Understanding Spot Colors
Linkedin Learning: Spot Colors

Color Management | i1Display Pro

Check out an i1Display Pro from the IC to correct the color on your monitor, tablet, or mobile device. For information on how to profile your device, please visit our step by step instructional guide by clicking HERE.

Checkout Policy

To calibrate your laptop or device, make a reservation appointment via Calendly to check out a device from the Imaging Center.

Equipment can only be checked out in person by appointment. The IC does not accept ‘walk-ins’.

Imaging Center equipment checkouts are free for current CCS students, staff, and faculty.

Patrons must present a current CCS ID in order to check out equipment. No ID = No Checkout.

Students may keep the equipment for no more than 24 hours for each checkout and can renew the items one consecutive time. Students cannot check out equipment over weekends and school breaks (Thanksgiving, Christmas, Spring Break, etc.).

The patron is fully responsible for the care and safeguard of all equipment that they check out. The student is responsible for paying close attention during the time that the equipment is being checked out to them. Read and sign the check-out agreement to avoid mistakes.

The patron must check for equipment damage before they take it. Report any faulty equipment and return it immediately.

Paige using i1profile device — Paige S. (former work-study student) calibrates her laptop in the 2018

Return Policy

All equipment must be returned on time.

A return time & date will be agreed upon when you check out the item. A calendar appointment will be made on your behalf as an appointment for you to return the item.

All equipment must be returned in the condition in which it was checked out (cords wrapped, cases packed neatly and clean).

It is encouraged that the patron stays and observes the IC staff while they check in returned equipment.

All checkouts returned to the Imaging Center before 3:30pm on Fridays.

Equipment will be sanitized upon return to the Imaging Center.

An example of calibrating a monitor — IC computer being calibrated in Fall 2020

Overdue Equipment Policy

Students, Staff, and Faculty are subject to late fines and replacement fees. Emails are sent via CCS email to notify the patron of overdue equipment.

Equipment overdue by more than 24 hours will result in the suspension of checkout and potentially printing privileges.

Equipment overdue by more than 72 hours will result in a replacement fee and indefinite suspension of check-out & printing privileges. Students will have a hold placed on their academic accounts.

Lost, stolen, or damaged equipment will result in a mandatory, non-negotiable, full replacement or repair charge.

An official police report must be submitted for stolen equipment or we will assume that you, the patron, stole the equipment.

Consecutive overdue returns may result in the semester suspension of check out and/or printing privileges.

Threatening or rude conduct toward any IC staff member will result in the permanent loss of your checkout and/or printing privileges.

Fines may be paid in the Imaging Center.

Only IC management can override policy terms

Color Management | i1Display Pro

Check out an i1Display Pro from the IC to correct the color on your monitor, tablet, or mobile device.

If this is your first time calibrating your computer, download the i1Profiler application from the X-Rite website and install it onto your computer by clicking HERE

Open the .dmg package and follow the prompts on screen for installation. Installation will include a computer restart.

Profiling Your Device

Before you begin

Ambient light affects profiling outcomes. Set your computer in a place you plan to work often.

Make sure your screen has been on for 20-30 minutes. Turn off any settings that could possibly change the normal temperature or brightness of the screen while in use. (i.e. Night Shift, Low Power Mode, Screen Saver, etc.)

Don’t forget to clean your monitor so that it is free from fingerprints!

Quit any applications and turn off all settings that might interfere with calibration, such as pop up notifications, flashing updates or messaging services.

In System Preferences, ensure the following preferences are set:

system preferences - display — **Displays** *> Uncheck “Automatically Adjust Brightness”*

system preferences - accessibility — **Accessibility** *> Display > Set Contrast Slider to “Normal*

system preferences - energy saver — **Energy Saver** > Uncheck any power savers that would affect the calibration process

Calibrating Your Monitor

Open the i1Profiler software & connect the calibrator to your computer using the USB cord.

User Mode > Basic

Application Settings > set the Default display device to i1Display

From the Workflow Selector (left column), select the Display Profiling button.

Display Settings

Select the display you are profiling and the type of monitor. In most cases, the program will automatically select it for you.

White Point > CE Illuminant D65

Luminance > 120 cd/m²

Gamma > Standard (default) | 2.20

Uncheck > Adjust profile based on my ambient light

Select the Next button

Note: D50 and D65 are the most common temperatures. D50 is a warmer white used for commercial CMYK printing (IC laser printing) and imitates the yellow-cast of paper. D65 is cooler in color and is best for inkjet printers (IC inkjet printing). D65 is also a good setting for photography and digital output. If you are undecided, use D65.

80 cd/m² is the lowest level and 250 cd/m² the brightest. 80-120 are the preferred luminance levels to see shadows. If you prefer to keep your current screen brightness level, select “Native.” The program will retain your current level of screen brightness and profile accordingly. If you are unsure, 100-120 is recommended.

Display Hardware Setup

If your computer has Automatic Display Control (ADC), check the ADC box. If you are unsure, undecided, or know your computer does not have ADC, use the manual mode.

Check > Adjust brightness, contrast, and RGB gains manually.

Select > Start Measurement

Measurement

Place the measurement device onto your screen using the counterweight provided on the USB cord.

Follow the instructions on the screen to adjust your brightness. Get as close as you can; the brightness is usually not a perfect match, but the device will calibrate according to your brightness.

The computer will then flash different colors and the spectrophotometer will calibrate based on these colors.

When prompted by the program, remove the i1Display device from the screen, turning the diffuser back over the lens.

i1profiler - final measurement comparison

Once finished, the program will display a series of patches split into before and after triangles. Each triangle pair should only differ in value. If any pair are a completely different color, it is likely that a screen pop up interfered with the calibration process, and the measurements must be taken again.

If the patches are correct, click Next or select ICC Profile.

Name your profile; include date and monitor type. Example: 2018-01-30-Macbook-Office.icc

Set user access for the profile.

Set up a Profile Reminder of 1-4 weeks. If you are doing color-critical work, profile every week. Otherwise, every 2-4 weeks should be sufficient.

You can view results and select “before” and “after” images as examples of your improved color.

Color Management | Converting a Color Profile

By converting a color profile, the color numeric numbers change. Converting your color profile permanently moves your image into that color space. It is the last step prior to saving the file for print.

Edit menu > Convert to Profile.

Under Destination Space, choose the color profile to which you want to convert the document’s colors. Under Conversion Options, specify an engine and a rendering intent.

Toggle on the Preview option. Click OK.

What is a rendering intent?

A rendering intent is a method or set of instructions for mapping or translating color values from one color space to another, generally when converting from a color space with a larger gamut to one with a smaller gamut.

Absolute Colorimetric:

Leaves colors that fall inside the destination gamut unchanged. Out-of-gamut colors are clipped. This intent aims to maintain color accuracy at the expense of preserving relationships between colors and is suitable for proofing to simulate the output of a particular device.

Relative Colorimetric:

Compares the extreme highlight of the source color space to that of the destination color space and shifts all colors accordingly. Out-of-gamut colors are shifted to the closest reproducible color in the destination color space. Relative Colorimetric preserves more of the original colors in an image than Perceptual. This is the standard rendering intent for printing in North America and Europe. The Imaging Center’s RIP is also set to use this rendering intent.

Perceptual:

This method may shift all colors slightly in order to retain the tonal and color relationships throughout the image. It may sacrifice absolute color accuracy, but it is good for preserving tonality and natural hues in an image. Good for photographs. This is the standard rendering intent for the Japanese printing industry.

Saturation:

This method maps saturated colors in the source space to fully saturated colors in the destination space at the expense of tonality and color accuracy. This is only good for “business presentation” type applications where bright saturated colors are more important than the exact relationship between colors.

For More Information

Adobe: Color management settings for the best print output
LinkedIn Learning: Understanding Rendering Attempts

Color Management | Assigning a Color Profile

Assign Profile allows you to tag an image with a specified profile or untag an image by removing it. No color numeric conversions are made; it simply applies an interpretation to the numbers in the image.

Edit menu > Assign Profile.

Toggle on the Preview option. You will most likely see the colors shift on screen.

In the Assign Profile dialog box you will see three options:

Don’t Color Manage This Document
Removes the existing profile from the document. After you remove the profile from a document, the appearance of colors is defined by the application’s working space profiles.

Working [color model: working space]
Assigns the working space profile to the document.

Profile
Selecting this option allows you to toggle between different color profiles. Adobe assigns the new profile to the document without actually converting colors to the profile space. This may dramatically change the appearance of the colors as displayed on your monitor.

Examples of Different Profiles

Notice in the examples below – how the colors appear richer or duller depending on which profile you are assigning the image.

sRGB

sRGB is a color space that defines a range of colors that can be displayed on-screen and in print. It is the most widely used color space and is supported by most operating systems, software programs, monitors, and printers

Adobe RGB (1998)

The Adobe RGB color space is a color space developed by Adobe in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary colors on a device such as a computer display

ProPhoto RGB

The ProPhoto RGB color space is an output referred RGB color space developed by Kodak. It offers an especially large gamut designed for use with photographic output in mind. Most printers cannot achieve some colors of this gamut and may not print as bright.

CMYK

The CMYK color model is a subtractive color model, based on the CMY color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four ink plates used in some color printing: cyan, magenta, yellow, and key

For More Information

LinkedIn Learning: Understanding Color Management
Adobe: Keeping Colors Consistent

Color Management | An Introduction

The print process starts as soon as you create a file. It is a good idea to set your color preferences before starting to work. A color space is a range of possible colors.

The IC works in both an Adobe RGB 1998 and U.S. Web Coated CMYK (SWOP) v2 color space.

What is a Color Space?

A color space in general is a set of colors that has been defined in some way. Typically they are colors that a given device is able to display or print.

The set of all the colors that can be found in a given color space is called its gamut. If a color is outside of this range and thus for example cannot be displayed or printed, we say it is out of the gamut

How to Change your Color Settings

Photoshop - Color Management | Prepress 2

How to Change your Color Settings in Photoshop

Edit menu > Color Settings
Settings > North America Prepress 2

Do not change the color space by toggling between RGB and CMYK via Image menu > Mode. You will lose critical pixel data by using this method.

How to Change your Color Settings in Adobe Bridge

It’s good practice to synchronize your color settings in Adobe Bridge.

With Bridge open, do the following:

Edit menu > Color Settings
North America Prepress 2 > Apply

For More Information

Adobe: Keeping Color Consistent
Linkedin Learning: Understanding Color Management