A quick check online convinces me that a lot of folk – designers, artists and printers – are frustrated with gradients that print with banding, or clearly dileneated “steps” of color visible in both digital and offset printing and which can be even more dramatic in wide format output. The bottom line is that those sweet gradient tools in your design software do not come with warning labels to prepare you for the resulting output in print. Gradients will normally (but not always) look good onscreen, but the technology to print them with similar ease falls short. The current best solution is to apply PhotoShop effects to minimize or hide the banding. The drawback is just like a great medication with a not-so-great side effect, this can produce unwanted results: colors can shift and the image may print “grainier” than originally planned.
A radial gradient should ideally look smooth, like a sunburst. The sample below, however, shows how it generally prints like the Looney Tunes logo.
There is no fix for the banding problem when saving your Illustrator files. We’ve often searched for that magic button, with no luck. Below are a few photos from a recent experiment where a stubborn orange-to-yellow gradient in a client’s wide format pop-up display printed with visible, distracting banding regardless of file type, compression or other options used. Saving the file as eps, pdf, opening in PhotoShop, increasing resolution, optimizing with PitStop…. no luck. Each resulted in the same diagonal “steps” in color.
The reason these efforts fail lies in mathematics and the physics of print, and I will admit to having only a shady understanding of these technical causes. For the scope of this post, let’s just point out that there are only so many “shades” or steps between one color and the next that are renderable in print. Your goal is to make a smooth transition from one color to the next, and the CS software makes that very easy in the design phase. However, the factors at play when you try to print your creation are the size or amount of space over which that transition occurs on the printed piece, the colors you have chosen to blend, and the resolution of the printer. Mathematically, at some point the printer has to go from one “step” to the next – and often the result to the human eye are bands or lines at which those changes occur. If you have chosen colors that are close together, you have even fewer “steps” between them with which to work. While PhotoShop, Illustrator and InDesign generally render smooth gradients onscreen, the science behind image rasterization and both offset and digital printing is not so forgiving to the viewer.
The fix for our wide format print in this case was to take the gradient portion of the job into Photoshop (it was originally created in Illustrator, we think!) Step one: we applied a Gausian Blur. The amount? Well that completely depends on the image. I just decide visually, bearing in mind whether or not the image I am working on is viewed at full-size onscreen or will be enlarged when printed out. A small grain visible now will be twice as large if printed at 200%. Next we created a layer with the mode set to Overlay and checked the box “Fill with Overlay-neutral color (50% gray).” To this layer we added Noise. Again – I decide visually how much noise to use (that’s an odd statement if you think about it!). Unfortunately, it is a guessing game, but with experience you will know best how much “graininess” or added texture will be acceptable without being enough to distract or compromise the output image.
The result here was a minor shift in colors and a slight visible texture or graininess that wasn’t there before. But both served to hide the banding problem! Both were acceptable results as the overall appearance of the gradient was smooth and pleasing.
Tips to prevent or minimize banding in gradients are easy to find online, but often your individual design is built in such a way that many of the tips seem unworkable. Like ours, the most common banding-buster tips require you create (or recreate) your gradient in PhotoShop as we did above, and then add noise to the image. However, you might have other elements in your design such as type, vectors or other effects applied in either Illustrator or InDesign which prevent you from moving the entire file into PhotoShop. If the file has been received from another person or client, then you might not have access to the individual pieces of the file and would be stuck trying to put the entire document into PhotoShop as an image in order to play around with possible filters. Apparently there is no “one size fits all” fix for this frustrating problem. Designers should be aware that gradients present difficulties and often require cooperation with your printer ahead of time to avoid unpleasing results.
Printers understand communication and design. Your printer should be able to provide you with the latest information, inspiration, technical advice, and innovative ideas for communicating your message through print, design and typography, signage, apparel, variable data printing and direct mail, integrated marketing and environmental responsible printing. They should also be able to work with you to solve any difficult prepress issues with your files. If they can’t, you have the wrong printer! The best advice, always, is to ASK YOUR PRINTER!