Flipped for Lenticulars!

“Same old slippers,
Same old rice,
Same old glimpse of Paradise.”
— William Lampton, 1859-1917

Lenticulars have been around for hundreds of years in one form or another. Painters used the technique as early as the 17th century and a photographic version was demonstrated in 1908. The modern lenticular started in the 1940s with the invention of the plastic lens. But despite this rich history, the process is still not widely understood by laypeople.

A lenticular lens is a ribbed plastic sheet that consists of an array of thin, parallel optical lens elements calledlenticules. These miniature lenses create a convex perspective of multiple images. A lenticular print consists of two or more graphic images that have been interlaced together in corresponding parallel strips in a single print. The lenticular lens, when placed over the interlaced image, focuses the eye on each of the different images within the print as the eye moves in a horizontal plane across the front of the image. Each interlaced image appears separately as a whole. So, as someone walks past the finished lenticular graphic they will alternately see each of the original unique images that made up the interlaced lenticular graphic.

There are four main types effects that can be achieved using lenticular technology — flip and motion graphics, 3D and depth images.

Flip graphics bounce visually between two or more different images. Two or three images are usually all that are used for this effect. These are the original lenticulars, like the old Cracker Jack promotions from the ’40s.

A motion graphic is just a more complicated version of the flip. They appear to show an object in motion, like frames from a short video clip. This requires a series of 30 or more images to show the motion. They are run through the interlacing software to create the final “movie”.

3D lenticular images are like a poor man’s hologram. They offer simulated three-dimensional imaging that is very convincing when done correctly. To create a 3D effect, photos are taken of the object from different perspectives. These photos are then transferred onto the lenticular layers so that as you look at the graphic from different angles, you see different angles of the object. This creates a very realistic 3D effect.

Depth images are created by layering objects in a file. The lenticular software allows a visual depth to be chosen for each of the layers and the final effect is that of a three dimensional space. Changing viewing angles allows you to see “behind” the objects in front.

There are also two types of lenticular lens angles. The viewing angle for 3D and depth images will be less than thirty degrees. A lenticular lens sheet designed for flip and motion images will have an angle wider than forty degrees. There are also general purpose lenticular lens sheets with a viewing angle of about thirty five degrees, but these do not provide the same quality of results.

To create a lenticular graphic, each image in a series is sliced up by the interlacing software and the image slices are alternated. So, for instance, the slices of a three-image lenticular would be image A(slice 1), then image B(slice 1), then image C(slice 1), then A(slice 2), B(slice 2), C(slice 2) and so on until all the slices are arranged onto a single graphic. The number of possible slices is determined by the number of lenticules per inch (lpi) on the plastic lenticular lens sheet overlay.

Lenticular lens sheets are available in different thicknesses, angles and lpi resolutions. Large format printers are generally restricted to 30 to 60 lpi for lenticular purposes. These sheets are available up to 4' x 8' and ¼" thick. Designations of more than 60 lpi are reserved for offset printing. These sheets are very thin and have a maximum width of about 20".

The closer the viewing distance, the higher the lpi number should be. For instance, 15 lpi lenses are quite coarse and not advisable for viewing less than 10 feet away. The ideal for close-up work is usually a 60 lpi lens with a one to five foot optimum viewing distance. The lenses focus the eye on each series of interlaced strips, depending on viewing angle. So, while approaching the print from the right, image A might be visible; while standing directly in front of the print you might see image B; and while moving past the print to the left, image C might become visible.

And yes, digital print shop owners can do this at home. There are a variety of interlacing software brands on the market now with intuitive interfaces and easy solutions to basic lenticular creation. Lenses in a variety of thicknesses and lpi designations are available from multiple sources as well.
Lenticular prints are usually run on inkjet printers and laminated to the backs of the lenses using an optically clear adhesive. There are also coated lenses available for direct printing on the new generation flatbeds equipped with highly accurate registration systems.

Lenses can be made from a large variety of modern plastics, but they generally break down into outdoor and indoor categories. The indoor lenses are typically soft, easy to work with and can be cut with a knife, but will yellow and become brittle with outdoor use. Better to spring for the harder, more expensive outdoor lenses if your lenticular will see a lot of direct sunlight.

Even though the technology is very basic and has been around for a long time, this is a product that still wows them in the digital age. Its effect is hard to explain. Some might call it a hokey little gimmick, but it never fails to draw a crowd. In recent years the best markets for large-format display type lenticular work seem to be with entertainment companies, particularly within the film and gambling casino industries; beverage companies that produce beer, carbonated beverages and performance/energy drinks (for their coin-operated machines); and retail store and museum display work.