Lenticular technology is a high resolution imaging process developed for the purpose of creating multi-imaging visual effects such as 3Dimensionality or animation.
This is achieved through four key elements of the production process.
1. Lenticular lens:
The lenticular sheet contains a precise parallel array of lenticules or lenses.
Each lens is capable of magnifying data.
The lens sheet is optically clear with a smooth reverse side where appropriate image is printed.
a. Origination: Any lenticular effect must be created from at least two complete in scale files. For example, a two image flip starts out as two separate files.
An animation can incorporate more files such as four, eight or twelve, which covers the sequence of the proposed animation.
A 3dimensional image works best with at least twelve separate files covering the spectrum of the prospective 3dimensional environment.
b. Interlacing: The art must be divided precisely among all the lenses that make up the final image size. The original images are actually sliced to fit into spaces equal to the width of each lens. For example a two image flip would be made with one-half of all the lenses containing image no.1 while the other half of all the same lenses would contain image no.2.
The process of interleaving the original files into the master which will match precisely to the pitch (number of lenses per inch) of the lens is called interlacing.
a. in lithographic printing the image is printed direct to the lenticular lens. This would require films to be output from an image setter. This again is a high resolution process requiring precise calibration.
b. Other methods of reproduction are for example digital photographic or inkjet where the interlaced master is output as a finished image which then needs to be laminated to the reverse of the lens in a separate adhesive process.
The most common method accounting for over 90% of the
lenticular imaging in the world today is direct to lens
lithographic printing. From high resolution films, plates
can be exposed and positioned in precise register on a
four colour process press.
Here for your review a description of the process of interlacing.
Sufficient bleed must be built in especially for 3D where the viewing angle will require extra (horizontal) data. The minimal final resolution is determined by the three variables of a) the lens design, b) the number of files you are employing, and c) the output capability of your image setter. For example, a 75 LPI lens (75 lenticules per inch) employing a twelve file animation or 3D image would create a pixel count of 900 per inch (75 x 12 = 900). To transfer this digital data accurately to film and to plate and finally to the lens substrate, an accurate multiplier of 900 PPI (pixels per inch) must be found on the image setter (for example: 1800, 2700, 3600, 4500 DPI (dots per inch). Should an exact multiplier not be available on the image setter, you would first interlace your files to the highest resolution available on your files, and then the interlaced master could be 'res'd down' (reduce resolution) to match the output capability of the image setter. It is critical that the data (the pixels that are sourced from your files) fit precisely into the lens. By following these procedures you will be able to calibrate the data properly.
The two images of the flip must fit into this space, so we will create in Photoshop a mask which will alternately cut and save half a lenticule of data, and then block the other half lenticule of data. If the lenticule measures precisely .0133" wide, the mask will be made up of 'openings' and 'blocks' which measure half of this size or .00665" wide each. The mask is used to grab the desired data from image A and save it into a master file, then grab the desired data from image B and save it in the same master file next to image A. The master file is now complete, and in theory if this master file was output through the image setter, the resulting films (or match print proofs) could be layed under the lens and you would witness the flip working in alternate viewing positions.