Lenticular is a type of printing process which allows printed images to simulate a number of visual effects when printed on, or laminated to, a special plastic substrate. A variety of 3-D and motion effects are achieved when the piece is manually moved or a stationary application is viewed from different angles. The applications may be very small such as the prizes found in popular snacks or they may be huge outdoor displays.

Special software programs are used to divide image files into narrow strips, which are reassembled in such a way as to create various optical illusions when printed on the plastic substrate. The digital files for these images are usually very large so computers with ample power and capacity are required. Needless to say, many lenticular printing projects can be quite expensive.

There are two methods that are most often used when creating lenticular images:

1. Printing the image directly to a special substrate:

The substrate contains rows of plastic ribs known as lenticules. These tiny ribbed lenses are evenly spaced on the sheet and may number as many as 200 lines per inch depending on the type of visual effect desired. The thickness of the plastic sheets may range from 0.007 inch, which is slightly less than 100 lb. tag paper, up to a thickness of more than one-third inch. The image is printed on the back (the smooth side) of the lens material.

2. Printing the image on a separate substrate and mounting it to the lens material:

When the printed image is completely dry, it is adhered to the plastic lens material. This can be quite difficult and requires the greatest degree of accuracy. If the image is not perfectly mounted, the desired effect will not be achieved.

A lenticular print application is not limited to one type of visual effect. More than one effect can be employed on a piece, depending on the type of image and the lens material that is used. Some of the visual effects that can be produced with lenticular printing include:

• 3-D: a lenticular piece simulating three dimensions is accomplished with the grouping of multiple pictures combined with shifted perspectives or layers.
  
  
• Morphing: when an image morphs, it transforms for one object into a completely different object. As many as a dozen variations in the transformation are possible with this technique.
  
  
• Zooming: depending on the angle at which the piece is viewed, the subject appears closer or farther away.
  
  
• Flip: a flip view is one in which an object immediately changes into something else when the angle of the piece is change. There is no gradual transformation between the before and after image as in morphing.
  
  
• Animation: changing the angle of the piece (the piece is moved manually or it is a large stationary piece and the viewer passes by or under it) results in an object appearing to move while remainder of the image appears stationary.

Lenticular printing requires exact registration. The smallest shift in registration during a press run will be quite noticeable on the finished piece. Equipment that provides the best possible registration is a must. Described below are three types of printing equipment that are often used for lenticular printing.

1. Direct Imaging Press:

Direct imaging technology provides for the direct transfer of the image from digital files to the image carrier (plate) of the press. A direct imaging press is basically a conventional offset press except that the image carrier (plate) is imaged directly on the press with the use of built-in laser exposure units. The quality and excellent registration achieved with DI presses makes them ideal for lenticular printing.

Some DI presses are used for printing the image on a separate substrate, which is adhered to the plastic lens material after printing. Other DI presses are capable of printing the image directly to the lens material if a UV inking system is used for curing special UV inks onto the plastic surface. For this type of application, it is necessary for the plastic lens material to be thinner than the material used for flatbed systems so that it is able to pass through the printing cylinders of the DI press.

2. Flatbed Inkjet Printer:

Digital images are printed directly to the reverse side of the lens material using special flatbed inkjet printers. Many of these printers are wide-format configurations that are used for large public display pieces. The lens material is positioned upside down in a vacuum frame, which holds it securely while the printing head passes over the material, depositing the ink to create the perfectly registered image.

3. Rollfed Inkjet Printer:

High quality rollfed inkjet printers are used (many of them wide-format) to print the image onto a separate substrate. The printed image is adhered to the back of the plastic lens material, requiring the lines of the printed image to align perfectly with the ribbed lenticules.