When printing images on sheet to be thermoformed into signs, retail displays, packaging, or consumer products, graphic designers must take into account the optical distortion that will occur when the flat printed image is formed into a 3D surface.

When printing images on sheet to be thermoformed into signs, retail displays, packaging, or consumer products, graphic designers must take into account the optical distortion that will occur when the flat printed image is formed into a 3D surface. The deeper the draw and the higher the relief of formed details, the greater the distortion. The solution is to "pre-distort" the original image (a technique called anamorphosis) so that subsequent stretching produces an undistorted final image. The difficulty is that, until now, there has been no means of determining how to achieve the anamorphic pre-distortion except through trial and error. Computer science now presents a more efficient solution, thanks to technology developed by Elastic Image, Inc., Terre Haute, Ind. This technology arrives when thermoforming of preprinted sheet is enjoying a surge of growth, thanks to the popularity of in-mold decorating for injection molded and thermoformed automotive and appliance parts. How it works As explained by founder and chief technology officer John S. Davidson, the technique involves printing a rectangular grid pattern on plastic sheet, forming a part using the customer's tool, and then measuring the distortion of the grid with a proprietary 3D scanner. The firm's special software then calculates how to pre-distort the original image to counteract the stretching of the surface during thermoforming. Elastic Image offers a range of services, which can include comprehensive project management from initial image design to printing and forming. Some customers provide an image design as a digital graphic file and Elastic Image supplies printed and formed products. In some cases, customers provide an image in electronic form, plus a forming tool or sample part, and Elastic Image performs its distortion analysis and then returns a pre-distorted electronic image file to the customer, which conducts its own printing and forming. Elastic Image has worked closely with Eastman Chemical Co., Kingsport, Tenn., which is helping to promote this anamorphic technology. As Davidson explains, this association arose because most of his initial applications in signs and displays have involved Eastman's thermoplastic copolyester materials, which have good printability and formability.

Eastman Chemical Company
Performance Plastics
P.O. Box 431 Kingsport, TN 37662
Phone (423) 229-2278 Fax (423) 246-1316