Lenticular printing is a multi-stage printing process involving the creation of a lenticular image from a minimum of two images which are later combined with a lenticular lens. The objective is to produce several frames of animation for the simulation of motion effect, counteraction of the different layers at specific increments for the creation of a 3D effect or for depiction of alternate images for a transformation illusion. After the collection of these images, these are flattened into separate, different frame images and then combined into a final file through interlacing (Levy, 2007; Lotka et al., 1999).
Lenticular printing history can be traced back in 1692 when the concept of 3D effects and images were demonstrated by French painter Gois-Clair. He found that he can obtain a dimensional illusion on canvas by interposing a lattice between the observer and the painting. To achieve this, he painted two different pictures on a plane surface and placed a grid of vertical strips. An observer looking at the painting from one side would see a complete painting and when the observer is looking at the other side, he would see a completely different painting (Figure 1a). If the observer views the panel at the center, he would see a blend of the two images (Lotka et al., 1999).
The word “lenticular” was first used in the patent to refer to linear lenses which were produced as early as the 1930s when Victor Anderson from New York invented the material at his company called Vari-Vue International. The cost of plastics then was prohibitive for the wide adoption of the technology which changed in the coming years with the lowering of the cost of PVC and the emergence of a new material called PETG. This development coupled with advances in output, proofing and business applications led to the mass production of products related to lenticular technology (Levy, 2007).
A lenticular lens is a solitary convex lens that amplifies light through a prism principle. The word lenticular, coined by Joseph Robert Fraler a physicist from Texas, is used to refer to a printed image characterized by depth or motion effects upon change in viewing angles. The term lenticular is used to generally refer to the lens effect which produces a convex perspective of various images or light origins but not an actual printed image (Figure 1b). Lenticular technology originated in the 1940s and was developed in recent years for the rendition of increased motion and depth. It has found great application for marketing and related fields (Broomberg, 2007).
The principle that makes a lenticular print work is the use of a plastic sheet that covers the printed image (Figure 1c). The sheet is designed to have the physical feature of dozens of minute lenses or prisms per inch. There are two methodology options for the printing of the image. One is printing the picture on a particular material which is then overlaid by the plastic lens conferring the lenticular effect. The other is printing the image directly on the surface of the back of the lens instead of simply overlaying the image with a plastic lenticular film. The structure of the lenticular print can be used to exhibit two or more different images through changing the viewing angle of the observer. A video can even be produced when 30 or more images are taken and put together (Lotka et al., 1999).
There are three major image types of lenticulars based on the effects that are produced using the technology; these are flip images, animated images and 3D depth images. Flip images are the most basic type of lenticulars. It consists of two images that are printed on the similar panel. These images are aligned and printed at the back of the lenses. It is the viewing angles that determine which of the two images are viewed at a particular time (Levy, 2007).
Next to flip images are animated images. Animated images are produced when around more than ten images are interlaced together in the same manner as in flip images differing only in the number of images used. The animation or image of action of the subject is produced as the observer views the print in changing angles (Lotka etl al., 1999)
The third type, 3D depth images, is more complicated than flip and animated image types. 3D depth images utilize the bio-physical phenomenon called parallax which allows observers to perceive images in three dimensions. Parallax is naturally created by the different viewing angles of human eyes. During this process, the human brain compares the separate views which are observed by the right and the left eyes and then processes these data resulting into a world in three dimensions (Nur Microprinters, 2006; Norscreen, 2007).
Figure 1. Lenticular printing principles and components: barrier system (a),
lenticular system (b) and lenticules (c) (modified from Levy, 2007).
Lenticular prints can be mage from different materials such as PVC or plastic, APET, acrylic or PETG. Of these four materials, PETG and APET are the most commonly used although other substrates such as PVC and acrylic have found various applications particularly in outdoor use and novelties such as gift cars and cups (Bromberg, 2007; Levy, 2007).
. At present, ideal applications are found in trade show graphics, airport and train terminal displays, bus terminals, store product promotions, posters, exhibitions, vending machines and other forms of retail (Lotka et al., 1999).
Recently, there were large format applications which use over 80 inches lenticular prints for bus shelters and inside movie theaters which are achieved using oversized litho-press. Furthermore, numerous advances have been taken in this growing industry to the properties of lenticular lens and the method of printing which has led to a lowering in cost and increasing of quality. Trading cards, magazines, posters and signs all have benefited in lenticular print technology (Nur Microprinters, 2006; Norscreen, 2007).
Previously, lenticular printing made use of lithographs and available materials. Nowadays, the most revolutionary changes that lenticular printing is experiencing are the digital applications of image and lenticule overlaying. Whereas in the past images are manually, meticulously and tediously combined by cutting and pasting segments of the images, at present many tools are increasingly becoming user-friendly and more available to ordinary hobbyists and enthusiasts. There are programs that can combine numerous images in a very short time. Software can be bought and downloaded from various providers which are offering cheaper and more sophisticated technology. At the same time, in addition to PVC and APET, other materials are being considered for more suitable application as well as cost-effective approaches. This implies that the production of images and the placing of lenticules over these images are now being facilitated by mathematical calculations to prevent misplacement of the lenticules over the images. In addition, the printing of the images plays a crucial role to the effect that is needed. For example, interlacing of more images can provide a smoother and rounder 3D effect (Levy, 2007).
In terms of more sophisticated digital programming for the image in lenticular printing, there are programs for the reduction of error diffusion in order to obtain high fidelity in lenticular screening. Modern halftoning algorithms are being developed to improve the quality of lenticular images with digital printers (Lau & Smith, 2006)
In terms of management, there are three pivotal area where lenticular printing can be efficiently handled. These include the turnaround of the technology, the speed of production and the quality of lenticular prints produced.
The first management area assesses the time wherein customers adopt the product, particularly lenticular prints, and the period of the development of these prints. Generally, turnaround time is dependent on the demand for these products. Since there is an insignificant lag time in the production of lenticular prints nowadays because of available technology, the turnaround can be made less dependent on production. Faster production would mean faster turnaround time (Nur Microprinters, 2006).
The second management area identifies the different levels or factors involved in lenticular print technology for the determination of its speed. These can be technology itself which are the preparation of the images to be interlaced, the interlacing of these images, the overlaying of lenticular layer and the manufacture of these lenticular layers itself. If raw materials and production protocol are already established, or better, if there are available advanced technologies, speed is greatly improved. Software and manufacturing of special lens types are largely contributory to the speed at which lenticulars are being processed in these modern times (Daravath, 2003).
Quality, the third management area, should never be compromised in the quest for higher production speed and turnaround time. Competitive software and material providers reassure costumers that production quality is a priority. Many are providing this type of technology in different regions of the world and more advances are being integrated. At the production area, quality can be assured by closely monitoring each step. This can be achieved either through hiring of quality assurance personnel or through installing testing equipments and following standard assessment protocols (Nur Microprinters, 2006).
Specific problems are associated with lenticular printing technology. These include misalignment, wrong pitch, wrong resolution and calibration. Misalignment of images and the lenticular sheets happen when the lens is not horizontally aligned with the platform to which these are pasted. This error will result to a print possessing a wave or skewed effect. Wrong pitch on the other hand results when the above error is committed resulting to a vertical wave effect. Wrong resolution is a result in unnecessary modifications on the original image that is to be given a flip, animation or 3D effect. Alteration on the image will lead to presence of a vertical wave or banding. The last problem involves calibration since lenticular prints amplifies small points such as inaccurate calibration. In this error, glow protrudes in the area of any non-calibrated hue which results to a blurry appearance of the image (IPA, 2007; Nur Microprinters, 2006).
In summary, lenticular print which has a long and rich history, is a very promising technology because of the interesting features it lends to images which are flip, animation and 3D effects. Its production was limited in the past because of prohibitive material costs and the complications of the process.
Nowadays, modern technology such as digital printing and software are revolutionizing lenticular printing which has gained wider acceptance in different areas of the printing industry sector.
Moreover, management strategies aimed at the improvement of turnaround, speed and quality of lenticular prints are being applied for the maximization of its potentials. However, there are still limitations and these are particularly highlighted in the error-prone areas such as alignment, pitch, resolution and calibration although there are steps identified for the prevention of related errors.
Clearly, lenticular technology promises lots of potential for commercial succes and circumventing the above challenges coupled with adoption of newer technologies can help provide a more valuable niche for lenticular printing.
Bromberg, I. (2007). The benefits of lensfree printing. HumanEyes Technologies. Retrieved August 4, 2007 from www.humaneyes.com/uploads/File/LensFreeWhitePaper.pdf.
Dharavath, H.N. (2003) Importance of technical competencies in the graphic communications technology curriculum as perceived by the graphic communications industry and educators. Journal of Industrial Technology 19, 2.
IPA. (2007). A process for graphics workflow excellence. Association of Graphic Solutions Providers. Retrieved from August 4, 2007 from www.ipa.org/pdf/IPA_e-Lean_Introduction.pdf
Lau, D.L and T. Smith. (2006). Model-based error diffusion for high fidelity lenticular screening Optics Express 14, 8.
Levy, S. (2007). How to make lenticular images. Gravitram. Retrieved August 2, 2007 from http://www.gravitram.com/how_to_make_lenticular_prints.htm.
Lotka, B., Schminke, K. and Krause D.S. (1999). Exploring lenticular prints. Digital Fine Art, 44-48.
Norscreen. (2007). Norscreen Lenticular: Think in a new dimension. August 4, 2007 from www.norscreen.co.uk/pdf/Lenticular%20sheet.pdf
Nur Microprinters. (2006). Lenticular workflow. Corporate Marketing. Retrieved August 4, 2007 from www.nur.com/NR/rdonlyres/C1AC864C-D7A9-4BA8-BF2CF137DFE5ACD/0/AppNoteLenticularV21.pdf