Lenticular Images

A lenticular image is a combination of multiple input images overlaid with a lensing material to provide a sense of depth, movement, or other change (depending on how the input images differ). The lensing material is a sheet of plastic molded into many tiny prisms. The Save Image panel in Chimera includes a lenticular image camera mode for saving a set of images that differ slightly in viewing orientation. Such a set can be used to make a lenticular image with apparent depth, a 3D image.

• prerequisites
• instructions

Making a lenticular image as described below requires the following:

• software to generate the input images, in this case Chimera
• software to interlace the input images into one image
  • several programs exist, varying in cost, performance, and platform availability
  • a trial version from ProMagic worked well in tests with Chimera (available for Windows, requires PhotoShop^®)
• a printer, preferably high resolution
• lensing material with optical adhesive already applied, such as from microlens.com
  • the appropriate material should be chosen based on the intended image type (in this case 3D), image size, viewing distance, and other parameters
• a cold laminator to eliminate air bubbles between the printed image and the lensing material

1. Find out your printer's resolution in DPI (dots per inch).

   For example, the UCSF Computer Graphics Lab (CGL) has an Epson printer with 720 DPI.

2. Note the chosen lensing material's LPI (lenses per inch). For best results, perform a pitch test to determine the effective LPI of the lens for your specific printer.

   The CGL has lenticular sheets in the portrait orientation with 60 LPI. These lenses were designed for 3D images and a viewing distance of 1–5 feet.

3. Prepare the scene in Chimera, avoiding the use of thin lines, especially vertical or near-vertical. Use stereo to see how much parallax is present. Overly strong parallax makes it hard for the eyes to fuse the two views together. One rule of thumb is to limit how much objects protrude in front of (or recede behind) the focal plane to approximately a third of the window width. The relationship of the objects to the focal plane and the window width can be viewed and adjusted in the Top View. You may wish to save your setup as a Chimera session. See also: tips on preparing images
   
   
4. Generate the input image files. DPI/LPI gives the number of files that should be generated (use the original LPI, not the pitch-test-corrected value).

   With CGL's Epson printer and the lenticular sheets described above, 720/60 = 12 images.

   In Chimera's Save Image panel:
   • Set the Image camera mode (near the bottom) to lenticular and indicate the number of images to save.
   • Turn on Use print units and set the image height and width to match the lens sheet (but make the image slightly smaller as needed to account for any alignment marks added by the interlacing software).
   • Set the desired Print resolution (dpi).
   • Click Save As... to compute the images.
   • When the save dialog appears, set the File type to an image format that can be read by your interlacing software.
   
   
   
5. Use the software to interlace the input images into one image. (We used software from ProMagic, but the procedure should be generally similar with other packages.)
   • Make sure the input images are in the left-to-right order (Chimera numbers the images in left-to-right order from 001 to N).
   • Doublecheck the image size, effective LPI, and type of interlacing (i.e., this is not a flip).
   • If the interlacer can save the output as a PhotoShop^® file (*.psd), use that option.
   
   
   
6. Print the interlaced image.
   • If the interlaced image lacks a color profile, assign it as Adobe RGB when you open it in PhotoShop^®. It may be necessary to alter the type of color correction done by the printer for a better match.
   • Make sure the image is printed at the specified size and resolution, as any scaling will destroy the lenticular effect.
   • The paper should be fed through the printer perpendicular to the lens orientation, because printers are more accurate and have a higher resolution in the dimension in which the print head moves (as opposed to the direction in which the paper moves).
   
   
   
7. Use a cold laminator to mount the image. Air bubbles should be eliminated; the trick is to go slow and only expose the adhesive a little at a time. Hand tools for applying wallpaper might work well enough. A hot laminator should not be used because it might melt the lensing material.