Lenticular images are images created by several images 'interlaced' together into a composite and mounted behind a lenticular lens. These images appear to be animated and possibly three dimensional depending on the artist's intentions.
Lenticular imaging has it's roots in the parallax barrier method, devised in 1692 by the French painter G. A. Bois-Clair. The barrier technique uses opaque bars to obscure part of an image and reveal others, carefully calibrated to the distance of the viewers eyes allowing the artist to show a specific image in relation to the viewer's position.
The lenticular technique is similar in the aspect that the viewer is subjected to an image based on viewing position. Lenticular images use a lens constructed originally out of glass to reveal the intended image rather than opaque strips to block the image. Modern lenticular lenses are constructed out of acryllic or PET copolymers depending on usage needs.
Before modern computer imaging became available lenticular images were painstaking to create, requiring specialized photographic and printing equipment. A tremendous amount of research and development was done from the 1920's thru the 1990's on these methods of producing images for lenticular lenses, but much has changed very recently.
Modern personal computers and common ink-jet printers now have the power and resolution to create images for lenticular lenses at the high resolutions required to fit many images under a single lens strip. An overview of lenticular imaging basics are outlined below. Please see the imaging section for information on creating images for LIC.
A lenticular lens is a clear plastic sheet with many (normally) vertical ridges or lenses embossed into the material. The vertical lens is precisely tuned to the depth of the plastic and the intended viewing angle showing the viewer only a portion of the image below the lens.
The lenses work on the physics principle of refraction (like most other transparent lenses). Refraction is a property of a transparent material that causes light to bend at the intersection with another material of a different refrative index.
An easily seen example of refraction is the visible 'shortening' of a person's legs as they stand waist deep in a pool of water: the change of refrative index from the water to the air 'bends' the light showing a different view than if the light travelled through the same material from the viewed object. Lenticular lenses use this property to only show a small strip under each lens according to the viewer's spatial relationship to the image. This is the effect that allows lenticular lenses to provide an illusion of depth and motion from a single static 2d image mounted behind or printed directly on the back of the lenticular lens.
Lenticular images can give the illusion of motion by 'flipping' between animated images frames. If several images, such as stills from a video, are interlaced and placed behind the lens the motion is shown as the viewer moves in front of the image. Many different techniques and software applications can be used to create motion, see the imaging section for more information on using digital imaging applications to create images for LIC.
Large movements, motions, and color shifts may not translate well to lenticular images. Small subtle movements can be just as effective and will maintain clarity for the viewer and prevent complaints of 'blurriness' inherent in fast broad movements. Proofing your concept first will give you insight on whether the movement you are attempting may work.
Different lenses provide different senses of motion, consulting with your lens provider will give you the best information on what lens to use for a specific purpose.
Exploiting the distance between our eyes and our natural ability to navigate 3-dimensional space, lenticular image illusions provide a sense of 3d and depth in two major ways:
Parallax effect: the apparent difference in location of an object viewed from several different angles creates the illusion of depth. As one walks in front of or sways to and fro before a lenticular image the apparent depth of the lenticular image reveals itself.
Stereo vision: a subset of the parallax effect, the apparent distance illusion is created by each eye seeing a slightly different image, tricking the brain into seeing 'stereo' or 3-D. A well crafted 3-D lenticular image will immediately appear to have depth to a viewer with stereo vision sense.
Most persons see the stereo effect (as it depends on two eyes and a sense of stereo vision) and nearly all perceive the parallax effect.
To create the 3d effect using lenticular images you must start with several images taken of an object from roughly the same distance at slightly different angles. Renderings from a 3d application are also excellent for this along with images created in Flash or After Effects with some thought put into the parallax effect. See the Imaging section for more information on creating images for LIC.
After you have created your image series, you can simply load them into LIC and create an interlaced image. LIC allows you to save projects with your image information, so you may set up a project and iteratively run through your pipeline to tweak your final image to perfection very easily. See more information in the Interlacing and Calibration sections.