Author: Michelle Peck

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

Registration & Trapping

The Risograph has limits of accuracy. Each color layer requires a separate pass through the printer, registration on multi-color Risograph prints will never be perfect. 

It is recommended that you add registration marks to your image to aid in lining up multiple layers. These can also double as trim marks if you plan on cutting down your print to size. 

Line work printed over solid blocks of color will usually look best.

Registration (aligning overlapping colors) can be tricky and often imperfect on the Risograph.

When colors are misaligned (misregistration), you can be left with a glaring white gap that can detract from your overall piece.

Trapping is a remedy to misregistration. Trapping is the practice of adding a little bit of overlap between adjacent colors to make sure that there are no white gaps between them even when registration is a little uneven. In other words, trapping expands pixels where color channels touch or overlap.

Trapping channels in Photoshop

Select all channels you want to trap.

Trap
Menu bar > Image > Trap…

Select the number of pixels or millimeters you want to trap. (We recommend you do the highest allowable.)

There will only be a slight visual difference in your file, but this will help your colors overlap once you print.

Click OK.

Risograph Image Options

The Risograph can print at 600 d.p.i. and has two gradient techniques to choose from:

  • Grain Touch: a randomized diffusion dither pattern (like a photo or film grain) 
  • Screen-Covered: creates classic halftone patterns on a very small scale.  
    • Screen Frequency controls the size of dots produced (higher numbers = smaller dots).
    • Screen Angle controls the angle that the pattern is set to.

We recommend using Grain Touch over Screen-covered. If you have questions about screen-covered and Riso halftones, please contact the IC.

Riso Printing | How does the Risograph Work?

An image is either sent digitally from the Riso PC or from a physical original via the scanner bed. The master is created by burning the image onto the master roll inside the printer. This stencil is then wrapped around the ink drum. The Riso feeds paper under the ink drum as it rotates, and ink is pushed out through the stencil to create an impression. 

On our Riso, two colors are printed at a time, and multicolored prints are made by switching out drums, then printing over each layer. The paper passes through the machine multiple times. 

Risograph ink is translucent, so its final appearance depends on the color of the paper it is printed on and the layering of each ink. Colors can be overprinted to create new ones. It’s also possible to blend any combination of tints of color together to produce color variants.

Ways to participate in CCS Riso

Trained students can rent time in the Riso Room year-round. The IC hosts Riso Printing events during the school year and student organizations (e.g. Riso Club, Freeform Press) use the Risograph for club events.

A brief explanation of how a Risograph printer works. Along with an introduction of the Risograph Studio in the Imaging Center.

Faculty & Staff

The Imaging Center will accept staff and faculty print jobs through the department print request form. If color prints or posters are being charged to a department, an 8-digit budget code number is required in order for the job to be processed. The appropriate account number can be obtained from your Program Manager.

Price Quotes

IC Techs will send you a print estimate when a print job is submitted via CCS email during our business hours. You will have the opportunity to approve the estimate and your job will be processed. If you submit a job outside of those hours, expect an estimate to be sent within one hour of opening the following business day.  

If you do not receive an estimate or price quote, please let us know. It is highly recommended that you calculate your own job cost prior to coming into the Imaging Center. 

Turnaround Times

Your print job will be completed in the order it was received. The standard turnaround time for the laser printers is 1 full business day. The standard turnaround time for the inkjet printers is 2 full business days. There are no “Rush” options currently. Please be aware that during midterms and finals, turnaround times can increase up to 2-3 business days. It is likely that your department request will be complete before this time. 

You will be notified via your CCS email when your job has been completed. 

Special Projects

We will work to the best of our ability in the Imaging Center to meet your special print and paper requests. Please contact Michelle Peck to talk about the logistics, such as scheduling needs or paper requests.

Sponsored Studios

For faculty teaching a sponsored project course, or any other course that will require large-scale printing, please contact Michelle Peck in the Imaging Center within the first few weeks of the semester with information on what type and how much printing is needed to complete the project and any major due dates.

In order to set up a student print budget, the Imaging Center will need a current class roster and budget authorization from the Office of Partnerships. 

More information on sponsored studio policies can be found HERE.

Personal Projects

Faculty & staff are welcome to print personal projects in the Imaging Center. The IC does reserve the right to extend the turnaround time for staff and faculty personal print jobs in order to complete the student and/or department workload.

Target Birds

Inkjet & Plotter Printing | Paper Resource List

This resource list is updated regularly. If you do not see one of these options in the drop-down menu while submitting a job, please write in the paper option on the form. Imaging Center staff will connect with you if that paper is no longer in stock.

Plotter Printer: Epson SureColor T5270D/T7270D

Standard Paper(s)
24# Bond Paper: 36″ & 42″ rolls
45# Bond Paper: 36″ & 42″ rolls
8 mil UV Microporous Photo Paper – 36″ & 42″ rolls

Specialty Paper(s)
Epson Backlit Transparency Paper: 36″ roll

For more information on our plotter printer, please visit HERE.

Inkjet Printer: Epson SureColor P5000

Standard Paper(s)
Enhanced Matte: 17″ roll
Watercolor – Radiant White: 13″ x 19″ sheets
Premium Luster: 16″ roll

Specialty Paper(s)
Exhibition Canvas Matte: 17″ roll
Hot Press Natural: 17″ roll

For more information on our desktop inkjet printers, please visit HERE.

Inkjet Printer: Epson Stylus Pro 9900

Standard Paper(s)
Enhanced Matte: 24″, 36″, & 44″ rolls
Doubleweight Matte: 24″ roll
Premium Luster: 24″, 36″, & 44″ rolls
Premium Semimmate: 24″, 36″, & 44″ rolls

Specialty Paper(s)
Exhibition Canvas Matte: 24″ & 36″ rolls
Cold Press Bright: 24″ roll
Exhibition Canvas Satin: 24″ roll

For more information on our wide format inkjet printers, please visit HERE.

Plotter Printing | Copier & Scanner Functions

The T5270D plotter is a dual-roll plotter printer and copier with a multi-function scanner. The T5270D can scan or copy up to 35.75” wide and 96″ in length.

General Information

Original files to be copied must be a minimum size of 12” × 18”. Any files that are 12” × 18” or smaller can be scanned in the 24-hour lab (on the 2nd floor) on a flatbed scanner at no cost.

By default, the Imaging Center will copy/print your image in the center of the paper roll. We can not determine the white border on your image. If you need a 1” white margin on each side of your image, save that within your file. You will be charged accordingly.

To drop off materials, please make an appointment via our Calendly. Files will be shared with the student via a shared Google Drive folder labeled Imaging Center – Scanned Files.

Scanned images will only remain on Imaging Center servers for three (3) weeks. The IC is not responsible for the loss of images scanned after three (3) weeks. 

Scanned images will be named: IC_lastname_scan.pdf/.jpg.

The Imaging Center does not resize any copy or scan requests. IC Techs will copy or scan images “as is”. The student will be responsible for resizing or color correcting each file.

Material to be copied or scanned must be submitted either rolled or wrapped in plastic.

Only paper-like materials will be accepted. Original material must be clean and free of dust, tears, and staples. See below for more information.

The standard turnaround time for the plotter/scanning process is 1 (one) full business day. Please be aware during midterms and finals, turnaround times can increase.

Accepted Media Types

  • Plain paper
  • Recycled paper
  • Tracing paper
  • Blueprint paper
  • Matte paper
  • Newspaper
  • Photo paper

Unaccepted Media Types

  • Documents with creases or wrinkles
  • Bound books
  • Documents with carbon backing
  • Documents with photos, stickers, labels attached either by tape or glue
  • Loose Leaf paper
  • Transparent paper
  • Cardboard
  • Plastic
  • Foam
  • Wood