Designing a Map for Printing in ArcGIS Pro
IGIS Tech Notes describe workflows and techniques for using geospatial science and technologies in research and extension. They are works in progress, and we welcome feedback and comments below.
Summary
Challenges Designing a Map for Print
COLOR
An essential difference between how colors are reproduced on a monitor and on paper is the color model. Monitors display color using combinations of red, green and blue light (RGB), whereas printers and plotters use four inks - cyan, magenta, yellow, and black (CMYK).
What You See is NOT What You Get
We all generally design maps with GIS software on monitors which use the RGB color model. If you're designing a map for the web, then what you see is generally what you get (within a small amount of variation due to different types of devices). However if you're designing a map to be printed, the colors on the monitor will not be what you see on paper. For one thing, the number of possible colors you can make with combinations of CMYK is simply a lot smaller than the RGB color space supports. They'll often be close, and for some colors and shades they'll be close enough. But many colors will come out different than what you expect (especially blues and greens), which can be a deal breaker when color fidelity is important (e.g., your company logo).
The best way to see what your printed map will look like is to refer to actual printed samples from the same or similar equipment that will do the final printing. This might include color samples from your printer, with the CMYK values indicated. The colors may look a little bright or fluorescent on your monitor, but the printed version should look like the printed samples (see also All black is not the same below). Ideally you can also get printed samples during the design process, and a final proof before you make 500 copies.
The second best way to preview your map is to use professional design software, such as Adobe PhotoShop or Illustrator. These programs know how to read your monitor's color profile, and display CMYK colors as faithfully as possible. ArcGIS Pro is not is this category, and the colors you see in ArcGIS Pro may or may not look the same when printed.
Thanks to black ink, black is the one color that is actually easier to print on paper than display on a monitor. However this is also the color that most commonly gets messed up when converting RGB colors to CMYK values. Technically, you can get something that looks like black by overlaying dots of cyan, magenta and yellow ink on top of each other. And that's often how software converts blacks and grays to CMYK. However aside from wasting ink, simulating black with a mixture of CMY ink can look mottled and even blurry if there's any kind of registration offset.
For text, outlines, and symbols, plain (or process) black (C0 Y0 M0 K100) is usually the best. This is because you don't want to count on multiple dots of colored ink perfectly registered, which is not always possible and can result in blurry text. This same recommendation applies to shades of gray - use percentages of K and no CMY.
Sometimes however you may have large areas of black where you want a richer (darker), warmer (reddish), or cooler (bluer) black (you need to look at print samples to see the difference). In these cases you can use a 'rich' black color, which will include a lot of black (K=100) but also a little bit of cyan, magenta, and/or yellow. However there is no universal 'rich black' formula. As one author put it, “Talk to the production house and ask them what rich black they prefer. There is no single rich black every print provider uses. Each print provider has their own formula for a rich black. And, in many cases, the print provider may want simply 100% K and they will adjust the black to match their own environment. Therefore, the best option is to ask the print provider how they like rich blacks handled”.
Ink application limits
Many printers also caution against exceeding ink density above 300; that means when you add the Cyan, Magenta, Yellow and Black values together, the total should be below 300. This is to prevent excessive ink from being laid down, which may not dry fast enough and can cause the sheets of paper to stick together.
White text on dark backgrounds
Displaying text in inverse colors can look stunning, but is harder to achieve on paper. Avoid fonts which are very small and/or thin.
Tip: Know your printing equipment
Whether your map is going to be printed on a desktop printer, plotter or commercial offset printer, it will be printed on a specific machine with specific settings for resolution, color profile, and paper size. For example, the offset printers at ChilliPrinting have a native resolution of 354dpi and require a 0.1" bleed on all sides. They also prefer the PDF/X-3:2002 export profile, fonts converted to curves, and C40-M0-Y0-K100 for rich black. The sooner you find out which printer you'll be using and the settings, the less work you'll have to (re)do at the end.
Page Size and Resolution
Other considerations for designing a map for printing include:
Page Size. When using a commercial offset printer, you may need to enlarge the page size a bit to incorporate an extra margin called a bleed area, which gets chopped off after the sheets come out of the printing press. For example if the bleed area is 0.1" and your map is 24"x36", you'd have to set your page size to 24.2" x 36.2". Check with your printer for details.
Margins. Commercial offset printers can generally print color all the way to the edge of the paper, as long as you've incorporated the bleed area into the page size. Plotters and desktop printers, on the hand, have a built-in margin area where nothing can be printed because that's where the rollers grab the paper. You should add Guides in your GIS software so you know where to stop adding elements.
Resolution. You also have to think about resolution, or dots per inch. Even the highest resolution monitor has only a fraction of the number of pixels in printed output. To avoid blurry output, this means i) you need to export your map at a high resolution suitable for printing (e.g., 300 dpi), and ii) any clipart you add to your map (e.g., a photo) needs to a suitable resolution. Just because it looks good on the monitor doesn't mean it will look good in the printed output.
Raster Clipart
Get your raster clipart as native CMYK image files whenever possible. This will give you the best color fidelity and smoother shades of dark colors. If you have access to clipart files that have been prepared in CMYK (e.g, by the art department), use those instead of RGB files.
Not all raster file formats support CMYK colors. For example TIF and JPG files support the CMYK color space, but PNG is limited to RGB. If you have a PNG file, you'll have to either convert it to CMYK before you add it to your map, or let ArcGIS Pro convert it (but see caution below). Likewise not all image editing programs support CMYK colors. PhotoShop certainly does, but many others don't.
Another consideration is the image compression. TIF is an industry standard for desktop publishing because it supports lossless compression - no loss in quality. PNG also uses lossless compression, and has become the defacto standard for web clipart. JPG on the other hand uses lossy compression. This results in smaller file sizes, which is good for webpage loading times but bad for printing. JPG usually works fine photos, even printed ones, but compression artifacts can be an issue for vector material saved as JPG. We often convert JPG images to TIF or PNG files, after applying a filter that removes artifacts.
Finally, don't forget about image resolution, or dimensions. A 100x100 image might look fine on a monitor, but if printed at 300 dpi it will be limited to 0.33" x 0.33". If you want it to print any bigger, you'll have to resize it in your GIS software or image editor before you add it. Either way, it'll get blurry. Vector clipart files don't have this problem.
Tips and Tricks for ArcGIS Pro
CMYK Color Palettes
Out of the box, ArcGIS Pro presents you with RGB palettes and color schemes (ramps). To set up a project for printing, there are a couple of steps you should do at the beginning of a project.
Install CMYK color Styles. Open a Catalog View (View > Catalog > Styles), then import any CMYK Styles you can get your hands on:
- For color schemes (ramps), add the built-in ColorBrewer (CMKY) system style. (Within ArcGIS Pro, open Catalog. Then right-click on Styles and select Add -- Add System Style -- Color and Color Schemes. Check ColorBrewer Schemes (CMYK) and click OK).
- For various shades of CMYK gray and black, you can download our cmyk_black.stylex Style file.
- For CMYK versions of the UCANR branding toolkit palette, see UCANR_2018_Colors_CYMK.stylx.
If you want to be a purest, you may consider deleting the default 'ArcGIS Colors' style (which contains all RGB colors and color ramps).
Among the most important colors to use CMYK values right-off-the-bat are shades of gray & black. As noted above, simulating black by overlaying CMY colored ink (C100-M100-Y100-K0) is less optimal than using process black (C0-M0-Y0-K100). Use process black for fills and outlines.
Manually add other CMYK colors. If you don't have all the CMYK colors you need through Styles, then you will have manually enter new colors as needed, saving them to your 'Favorites' style or a custom style. This will be most relevant for font colors, outline and fill colors for symbols, etc. You can get the CMYK values from printed samples, your art department, printed colors charts, Pantome color sheets, etc.
Among the most important colors to enter CMYK values are the darker tones, where the use of black ink improves output quality by reducing the amount of other inks required.
Select 'CMYK' as the color model for your Layout / Map. Right-click on the layout / map in the TOC, select Properties, and select CMYK as the color model. This will not affect how the colors appear in ArcGIS Pro, but determines the color model used when you export the layout/map.
Clipart in ArcGIS Pro
If you add PNG clipart files to your Layout, and the Color model for the layout is set to CMYK, ArcGIS Pro will convert them to CMYK when you export the layout. This works, but ArcGIS Pro's RGB>CMYK converter is not the best quality. For example 90% gray will become C90-Y90-M90-K0, which wont' look as sharp as C0-Y0-M0-K90. You're better off converting the clipart to CMYK using Photoshop which has a number of color conversion profiles.
Exporting
Your options for exporting a Layout for high quality printing are basically PDF or TIF. Exporting a Layout to PDF is convenient, but do a close inspection of the results (see problems reported below). For the best quality and control, export the layout to TIF and then convert the TIF to PDF in PhotoShop.
Exporting to PDF
Most people export a Layout directly to PDF. If you designed your map & layout with CMYK colors, and the color model of the Map or Layout is CMYK, this can work ok. However be sure to open the PDF in Acrobat and make sure the color model is CMYK.
Some disadvantages of exporting to PDF (not directly related to CMYK color space) include:
- the need to embed fonts
- limited ability to tweak the export parameters that ArcGIS Pro uses (e.g., image resolution or compression)
- potentially large file sizes (e.g., particularly when your map contains detailed vector layers)
- tiled rasters in the PDF which can produce visible grid lines (this was a deal breaker for us when producing a poster-size wall map which included a raster topography layer)
- ArcGIS Pro's RGB>CMYK conversion can not be configured and is generally of lower quality than professional publishing software
Exporting to TIF
Advantages to exporting to a TIF file include:
- TIF is a raster format, so all vector objects including fonts and feature layers are converted to raster, which often results in smaller files.
- You don't have to worry about embedding fonts
- TIF supports CMYK colors
- You can control the compression method - Deflate (zip) compression is lossless and generally works well for maps
- You can inspect the CMYK color values of individual pixels using an image editor like PhotoShop.
- TIF allows you to do the RGB>CMYK conversion in PhotoShop instead of ArcGIS Pro, which will give you more options and better results
- You can easily convert a TIF to a PDF in PhotoShop, which gives you more control over the export options
Other Export Quirks and Gotchas
Overall we found ArcGIS Pro to be a great tool for cartography. Nevertheless we ran into a couple of quirks with ArcGIS Pro version 2.2.1
- Errors exporting an image service. We had issues exporting a layout that contained an Image Service layer (specifically a multi-directional hillshade from ESRI's Living Atlas service). For reasons that are unknown and undocumented, only 5000x5000 pixels of the image service rendered in the output, both PDF and TIF. The workaround was to remove it from the map, and replace it with a local raster (in this case, we created our own multi-directional hillshade using a geoprocessing tool).
- Random duplicate labels. If you get weird duplicate feature labels in the output that do not appear in ArcGIS Pro, close ArcGIS and try again. We were not able to determine why weird duplicate labels occasionally appeared, but it was definitely an ArcGIS Pro glitch. Eventually they went away.
- Black dots around clipart. You may see ugly black dots around your raster clipart in the output, which look like dithering or stippling. This seems to be caused by ArcGIS Pro's internal resizing algorithm that kicks in if the original image is too small. For example, if you insert a 100x100 TIF file that is 1"x1" wide in the layout at 300 dpi, then under the hood ArcGIS Pro will have to increase the size of the bitmap by a factor of 3. This is where the ugly dots get introduced. The workaround is to enlarge the image in a proper image editor like PhotoShop, apply smoothing filters to deal with the artifacts if needed, convert to CMYK mode, and save it as a new TIF file.
Other Best Practices for ArcGIS Pro
Organize Your Layers
Map projects for print can have dozens of layers, including the data layers, masks, derived layers, layers just for labeling, etc. Keeping them organized takes a few extra seconds but can save you or a colleague a lot of effort as the map evolves (including future updates down the road)
- Use Layer Groups. Putting layers into groups by feature type (e.g., Transit, Topography) or function (e.g., Masks) can help you quickly find what you need and make sure layers aren't accidentally removed. ArcGIS Pro makes this very easy, just select a few layers, right-click, and select 'Group' from the popup menu.
- Give layers meaningful names. The default name of a layer is usually the name of the Shapefile or dataset. Sometimes this is interpretable (county_boundaries) but sometimes not (ne_pitfill=??). Rename layers with meaningful names to help you work with them six months from now.
- Delete or tag unused layers. Layers that are no longer needed should either be deleted from the project, renamed, or moved to a group for layers taken out.
Archive Your Work
When you're done with a project, archive it to a package file saved locally or an ArcGIS server (Share > Project). Be sure to enter a short description that would help someone / yourself continue working on it in the future. ArcGIS Pro packages can also contain file attachments, which could be used to package the fonts used, clipart files, etc.
Conclusion
There's nothing like a beautiful, well-designed wall map. GIS software makes creating beautiful maps a lot easier, but you need to understand how the printing process works and the characteristics of the equipment that will produce your masterpiece. Pay attention to colors, the resolution of any bitmaps in your map, and how you export the map for the printer. Knowing from the beginning where you'll print your map, and the recommended settings for the specific printer, will minimize the amount of work you have to do at the end and help ensure the final product looks just the way you want.