Option 2: Convert to Grayscale & Re-color

Option 2 | Convert to Grayscale & Re-Color

This method changes your piece to grayscale. You will manually add the colors back in by painting on Spot Channels. This can be time-consuming if you have a detailed color image.

Change your mode to Grayscale
  • Menu Bar > Image > Mode > Grayscale 
  • Click OK through the “Discard other channels?” warning. This process will also flatten your layers.

Your piece will be in black and white without any color information. You should only have one Gray channel.

Change your mode to Multi-channel
  • Menu Bar > Image > Mode > Multichannel
  • Click OK through the “Flatten layers?” warning. (This process will flatten your layers.)

Your single Gray channel should change to Black.

Change your Black Channel (your first color) to a Riso spot color 
  • Double-click on your black channel.
  • Use the eyedropper to select your desired spot color from the Riso swatches panel.
If you did not download the swatches file, you can find and add the Pantone equivalent color.
  • Click on the black swatch to pull up the Color Picker box. 
  • Click on Color Libraries and type in your desired Pantone color using the Riso color guide.

Because you only have one channel, the content in your piece will appear in grayscale. Click OK.

If your image appears washed out, feel free to change the values using Curves, Levels, or your own favorite method of adjusting Luminosity. I would suggest re-setting your black point using Curves:

Menu Bar > Imaging > Adjustments > Curves

Select the black point dropper and click on the darkest point in your image.

Add a second (or third or fourth) spot color as desired for your piece:
  • Go to the Channels menu panel.
  • Select “New Spot Channel…” from the drop-down menu.
  • Use the eyedropper to select your desired spot color from the Riso swatches panel. (Your first channel will now show up in color) 
  • Click OK

With your new channel selected, use the paintbrush tool to add in your new spot color. (Use a black swatch.)

Add a channel for each color you want to print.

If Option 2 color conversion works for you, skip ahead to Additional Optional Adjustments.

Option 1: Color Range Selection

Option 1 | Color Range Selection

Color range selection works best for pieces that are graphic and have only a few clear colors.

Select and convert a color to a Spot Channel
  • Select your first color range:
    • Menu Bar > Select > Color range…
  • Sample one of your colors using the eyedropper tool.
  • Use the Fuzziness slider to select more or fewer pixels. The white areas are the pixels selected. 
  • Click OK
  • With selected pixels loaded, go to the Channels menu panel. 
  • Select “New Spot Channel….” from the drop-down menu. 
  • Use the eyedropper to select your desired spot color from the Riso swatches panel.
  • Click OK

Your new Spot Channel will show up with your selected area as a mask. 

Repeat for every color. 

Make sure your composite channel is selected.

Change your mode to Multi-channel 
  • Menu Bar > Image > Mode > Multichannel
  • Delete all non-spot channels

If Option 1 color conversion works for you, skip ahead to Additional Optional Adjustments.

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.

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.

File Preparation for Riso Submission

Your files should be separated into individual black & white images for each color that is to be printed. This is similar to preparing files for screen printing. 100% black in each color layer, will print out as 100% of whichever color you are printing. 90% black will print as 90% and so on. 

Arrange layers in ‘print’ order.

File Prep

Prepare a multi-page PDFx file in the following specification:

  • B & W / Grayscale
  • Color-separated

Additional File Recommendations

  • Outline type: This is particularly important if you have manipulated or custom fonts.
  • Flatten: Be sure to keep a copy of your original file in case you need to make changes.

File Type & Page Order

Files submitted must be saved as a black & white, multi-page PDF file. Files should be color-separated and flattened. Each color should be black & white and on a separate page. Please see the fish example below

Your flattened PDF file should consist of 1-5 pages:

  • Page 1: Color 1 in B & W / Grayscale
  • Page 2: Color 2 in B & W / Grayscale
  • Page 3: Color 3 in B & W / Grayscale
  • Page 4: Color 4 in B & W / Grayscale
  • Etc.
Rendered Image (color composite)
Page 1: Color 1 (YELLOW) in B&W
Page 2: Color 2 (BLUE) in B&W

Naming Convention

YourName_FileName_Riso-colors-in-file-order | Example: RachelDeBoard_Plantlove_Black-HunterGreen-Lime.pdf

Color Composite Version

In addition to the color-separated pdf, upload a color composite (rendered) version of your final print. This is so the printer can check the proof against your rendered image.

Proof Approval

The IC requires proof approval of Riso prints, either in-person or via locker pick up, before giving a pick-up date and appointment. We do not offer digital proofs for the Risograph.

The IC will contact you via email when your proof is ready for pick-up. Once you approve the proof, we will email you a pickup date and time, and a link to sign up for a pick-up appointment. 


The Risograph printer has a resolution of 600dpi. Use this resolution for your images.

Maximum Printable Area

Tabloid – Printable Area: 10” x 16” 
Letter – Printable Area 7.5″ x 10″

For full-bleed design, add a security bleed of at least 1/4” around 3 sides of your artwork. Leave at least a 1” margin on the lead edge of the paper. 

The top 2” of the sheet of paper are where you are most likely to see roller marks or a series of faint lines carrying ink over from print to print. 

We offer letter size printing. However, we do not recommend it for heavily inked images. 

Type Weight & Size

Type size should not go below 6pt

The same text should not be printed in two colors, as misregistration will cause some illegibility. Do not set type in Photoshop, use Illustrator or InDesign to avoid your text being rasterized. 

Type size under 12pt should be set in registration black (100/100/100/100) and for type over 12pt use a 100% black.

Channels & Layers

When working with a CMYK file in Photoshop, when your file is ready to print, open the Channels Menu and select Split Channels. This will create new grayscale files, one for each color channel from your template. 

Alternatively, if you have prepared your color separations in layers instead of channels, you can use the File > Export > Layers to Files function to split them into individual files. Then open each file, convert it to grayscale, and print it. 

Double-Sided Printing

It is incredibly difficult to achieve a perfectly aligned double-sided print. 

Slight track marks from paper feeding rollers can also appear, especially when printing more than two layers and areas with heavy inking. 

Please make an appointment with IC staff to discuss your Risograph print submission. 

Need Extra Help?

If you have further questions about file setup, please contact us by email or by scheduling a consultation.

Reprint Policy

Print jobs must be paid for in their entirety upon pickup. Students must accept all liability with the set-up of their files prior to submitting the print job. This includes all spelling and layout issues.  

Occasionally reprints may be warranted due to printer malfunction or an IC technician’s error. Reprints must be requested before leaving the IC. The student may be asked to fill out a Reprint Request Form if a manager is not available to approve a reprint. Reprints must be approved by a manager.

If the issue can be immediately resolved, the IC will take the defective print and reprint the file in question without delay. The student will be responsible for paying the full price of the print job. If the issue requires printer maintenance or service, the student will be asked to leave the defective print with their completed form, and the IC will reprint the file once the service is complete, which may take several days.

The IC does understand that a student may need to take a defective print to show an instructor that the work was completed. In such cases, the defective print must be returned to the IC within 2 business days of the form being completed so that the printing issue can be addressed. Students are required to exchange the defective print in order to obtain a reprint or, if appropriate, another form of resolution. 

If the defective print is sufficient, the student may choose to purchase it at 50% off the full price. 

If the student wishes to keep the defective print in addition to receiving a reprint, it is their responsibility to cover the full price of the reprint and 50% of the defective print.

In the case of reprints, no changes to the original file will be allowed. The reprint will follow the original print specifications.

The Imaging Center rarely accepts claims of defective prints once they have left the IC. 

However, if a printer-specific defect (example: wrong image size, printer smudge, ink splotch) is discovered after leaving the IC, bring the print back immediately. Students have three (3) business days to return the defective print. If a defective print is reported more than three (3) business days after picking up the job, IC management will not consider a reprint or credit. 

This reprint policy does not apply to prints that are already mounted or framed. 

Once the print leaves the Imaging Center, complaints regarding fingerprint marks, scratches, or paper dents will not be considered.

Refunds are not an option except where a reprint is not possible.