Lenticular printing is a technology in which lenticular lenses (a technology also used for 3D displays) are used to produce printed images with an illusion of depth, or the ability to change or move as they are viewed from different angles.
Examples include flip and animation effects such as winking eyes, and modern advertising graphics whose messages change depending on the viewing angle. It can be used to create frames of animation, for a motion effect; offsetting the various layers at different increments, for a 3D effect; or simply to show sets of alternative images that appear to transform into each other.
Colloquial terms for lenticular prints include "flickers", "winkies", "wiggle pictures", and "tilt cards". The trademarks Vari-Vue and Magic Motion are often used for lenticular pictures, without regard to the actual manufacturer.
Process
Lenticular printing is a multi-step process that consists of creating a lenticular image from at least two images, and placing it behind a lenticular lens.
Creation and interlacing of images Once the images are collected, they are arranged in individual frame files, then digitally combined into a single file in a process called interlacing. Interlacing can be done manually using a raster graphics editor or using dedicated interlacing software.
Printing and assembly The interlaced image may be printed directly on the back (smooth side) of the lens, or on a substrate (ideally a synthetic paper) that is laminated to the lens. When printing on the backside of the lens, the critical registration of the fine "slices" of interlaced images must be absolutely correct during the lithographic or screen printing process to avoid "ghosting" and poor image definition.
Variations and effects The combined lenticular print shows two or more s by changing the angle from which the print is viewed. If a sequence of images is used, it can even show a short animation.
Though normally produced in sheet form by interlacing simple images or colors throughout the artwork, lenticular images can also be created in roll form with 3D effects or multi-color changes. Alternatively, several images of the same object, taken from slightly different angles, can be used to create a lenticular print with a stereoscopic 3D effect. 3D effects can be achieved only in a lateral (side-by-side) orientation, as each of the viewer's eyes must see them from a slightly different angle to achieve the stereoscopic effect. Other effects, like morphs, motion, and zooms work better (with less ghosting or latent effects) in top-to-bottom orientation, but can be achieved in both orientations.
Materials and manufacturing processes There are many commercial processes in the manufacture of lenticular images, which can be made from PVC, APET, acrylic, and PETG, as well as other materials. While PETG and APET are the most common, other materials are becoming popular to accommodate outdoor use and special forming due to the increasing use of lenticular images on items such as gift cards. Lithographic lenticular printing allows for the flat side of the lenticular sheet to have ink placed directly onto the lens, while high-resolution photographic lenticulars typically have the image laminated to the lens.
Lenticular images saw a surge in popularity in the first decade of the 21st century, appearing on the cover of the May 2006 issue of Rolling Stone, trading cards, sports posters, and signs in stores that help to attract buyers.
Construction
Each image is arranged (slicing) into strips, which are then interlaced with one or more similarly arranged images (splicing). These are printed on the back of a piece of plastic, with a series of thin lenses molded into the opposite side. Alternatively, the images can be printed on paper, which is then bonded to the plastic. With the new technology, lenses are printed in the same printing operation as the interlaced image, either on both sides of a flat sheet of transparent material, or on the same side of a sheet of paper, the image being covered with a transparent sheet of plastic or with a layer of transparent, which in turn is printed with several layers of varnish to create the lenses.
The lenses are accurately aligned with the interlaces of the image, so that light reflected off each strip is refracted in a slightly different direction, but the light from all pixels originating from the same original image is sent in the same direction. The result is that a single eye looking at the print sees a single whole image, but two eyes will see different images, which leads to stereoscopic 3D perception.
Types of lenticular prints There are three distinct types of lenticular prints, distinguished by how great a change in angle of view is required to change the image:
Transforming prints Here two or more different pictures are used, and the lenses are designed to require a relatively large change in angle of view to switch from one image to another. This allows viewers to easily see the original images, since small movements cause no change. Larger movement of the viewer or the print causes the image to flip from one image to another (the "flip effect"). An example of this is the lenticular print of hockey player Mario Tremblay at Centre Mario-Tremblay in Alma, Quebec, where he is transformed from a minor hockey playing boy as an Alma Eagle into the professional hockey playing man, four years later, as a Montreal Canadien.
Animated prints Here the distance between different angles of view is "medium", so that while both eyes usually see the same picture, moving a little bit switches to the next picture in the series. Two or more sequential images are used, with only small differences between each image and the next. This can be used to create an image that moves ("motion effect"), or can create a "zoom" or "morph" effect, in which part of the image expands in size or changes shape as the angle of view changes. The movie poster of the film Species II is an example of this technique. Stereoscopic effects Here the change in viewing angle needed to change images is small, so that each eye sees a slightly different view. This creates a 3D effect without requiring special glasses, using two or more images. For example, the Dolby-Philips Lenticular 3D display produces 28 different images.
Motorized lenticular With static (non-motorized) lenticular, the viewer either moves the piece or moves past the piece in order to see the graphic effects. With motorized lenticular, a motor moves the graphics behind the lens, enabling the graphic effects while both the viewer and the display remain stationary.
History
Predecessors
Tabula scalata
Corrugated images that change when viewed from different angles predate the development of lenticular printing. A few examples from the Paleolithic era exist in French caves. Tabula scalata or "turning pictures" were popular in England since the 16th century. Extant double paintings, with two distinct images on a corrugated panel, are known from the 17th century.
H.C.J. Deeks used a similar technique with minute vertical corrugations pressed into photographic paper and then exposed to two different images from two different angles. Under a 1906 patent H.C.J. Deeks & Co marketed a Puzzle Post Card or Photochange Post Card. In 1907 a Colorchange Post Card followed, featuring identical pictures on each side of the corrugations that were sprayed with different "liquid pigment or coloring matter" on (parts of) each side.
Barrier grid autostereograms and animation
The oldest known publication about using a line sheet as a parallax barrier to produce an autostereogram is found in an article by Auguste Berthier in the French scientific magazine "Le Cosmos" of May 1896. See pp. 229-231. Berthier's idea was hardly noticed, but American inventor Frederic Eugene Ives had more success with his similar parallax stereogram since 1901. He also patented the technique for a "Changeable sign, picture, &c." in 1903, which showed different pictures from different angles (instead of one stereoscopic image from the proper angle and distance).Ives, Frederic E., "Changeable sign, picture, &c.", U.S. Patent no. 771,824 (filed: October 27, 1903; issued: October 11, 1904). Léon Gaumont introduced Ives' pictures in France and encouraged Eugène Estanave to work on the technique. Estanave patented a barrier grid technique for animated autostereograms. Animated portrait photographs with line sheets were marketed for a while, mostly in the 1910s and 1920s. In the US "Magic Moving Picture" postcards with simple 3 phase animation or changing pictures were marketed after 1906. Maurice Bonnett improved barrier grid autostereography in the 1930s with his relièphographie technique and scanning cameras.
On 11 April 1898 John Jacobson filed an application for US patent No. 624,043 (granted 2 May 1899) for a Stereograph of an interlaced stereoscopic picture and "a transparent mount for said picture having a corrugated or channeled surface". The corrugated lines or channels were not yet really lenticular, but this is the first known autostereogram that used a corrugated transparent surface rather than the opaque lines of most barrier grid stereograms.
Gabriel Lippmann's integral photography
French Nobel Prize winning physicist Gabriel Lippmann represented Eugène Estanave at several presentations of Estanave's works at the French Academy of Sciences. On 2 March 1908 Lippmann presented his own ideas for "photographie intégrale", based on insect eyes. He suggested to use a screen of tiny lenses. Spherical segments should be pressed into a sort of film with photographic emulsion on the other side. The screen would be placed inside a lightproof holder and on a tripod for stability. When exposed each tiny lens would function as a camera and record the surroundings from a slightly different angle than neighboring lenses. When developed and lit from behind the lenses should project the life-size image of the recorded subject in space. He could not yet present concrete results in March 1908, but by the end of 1908 he claimed to have exposed some Integral photography plates and to have seen the "resulting single, full-sized image". However, the technique remained experimental since no material or technique seemed to deliver the optical quality desired. At the time of his death in 1921 Lippmann reportedly had a system with only twelve lenses.
Early lenticular methods On 11 April 1898, John Jacobson filed an application for US patent No. 624,043 (granted 2 May 1899) for a Stereograph of an interlaced stereoscopic picture and "a transparent mount for said picture having a corrugated or channeled surface".
In 1912, Louis Chéron described in his French patent 443,216 a screen with long vertical lenses that would be sufficient for recording "stereoscopic depth and the shifting of the relations of objects to each other as the viewer moved", while he suggested pinholes for integral photography.