Polaroid PolaChrome

Learn about Polaroid's Instant 35mm Film here and here.
PolaChrome is an additive color process. The film base is coated with a screen of minute, transparent red, green, and blue stripes behind which is a single, panchromatic silver halide layer.
The films resolution is considered 90 line pairs per millimeter (~2286 pairs per inch). There are approximately 1000 RGB triplets per inch.
Due to the color screen, the base film density of PolaChrome is approximately 3 times that of conventional slide film.

Lester Lefkowitz wrote a great book on the film titled "Polaroid Instant Slide System A Users Manual".
The book can be 'rented' from Archive.org here, or found on eBay.
In it he provided the following guidelines on scanning the film with electronic drum scanners.

  1. Align the film sprocket holes parallel to the long dimension of the drum. Place the emulsion side down, facing the drum.
  2. White balance must be calibrated on the PolaChrome film itself, not on a seperate gray scale. If there is no white image area, press a piece of tape very carefully over the sprocket holes only. The tape will remove the black coating and leave an area of clear base.
  3. When checking the other color values in the image, continue to keep the filter stripes totally out of focus.
  4. Turn off unsharp masking or the set the controls to minimum levels. If more than one scanning aperture is available, choose the largest aperture.
  5. Refocus the filter stripes before beginning the scan.
  6. Scan as you would conventional film. If the PolaChrome slide was exposed under proper lighting conditions, color balance should be similar to that used for conventional film, but tests will be required.
  7. If moire patterns appear on the separations, realign the slide on the drum at a moderate angle, about 30 to 40 degress, so that the sprocket holders are no longer parallel to the drum axis. If the moire pattern persists, realign the slide again and try a larger scanning aperture. An alternative method of eliminating moire has been suggested by some separators. Refocus the filter stripes in the film base, then slightly defocus - the stripes should be visible but blurry. Then increase unsharp masking to prevent the image from looking too soft.

The above was based on research done at R.I.T., which can be seen here.

Chromatic abberation is also mentioned in the book in a section on prints and enlargements.
"These patterns are usually noticeable only in large, even-toned, very lights areas, such as an almost white sky or a white building that pre-dominates the scene."
"The visibility of the pattern is related to the scene photographed, and on the enlarger alignment, the amount of chromatic abberation in the enlarger lens, and on the enlarger lens aperture."
"A properly aligned enlarger and a glass negative carrier to keep the PolaChrome slide flat may lessen the visibility of the pattern. The pattern may usually be eliminated completely by using a small enlarging lens aperture."

To outline recommendations:alignment of film and scanner lens is important; emulsion side towards the scanner lens; do not use sharpening; use a large aperture; use a small aperture; slightly defocus; use sharpening; flatten film if possible.

The recommendations are all over the place... "Do what looks best" in other words.
One must also take into account the density, resolution of the film, and RGB screen when digitizing.

While drum scanners are still preferred in very high quality applications, CMOS and CCD-based film scanners are more available to the general public.

The information contained in the following links outlines scan tests and results from CMOS and CCD-based scanners of various quality.
This is by no means an exhaustive resource, but simply meant to provide some visual guidance to others interested in this film.
Quality CCD-based scanners will produce the best results as some recommendations can be adhered to.

Scanning PolaChrome with Nikon Coolscan V ED
Scanning PolaChrome with Epson Perfection 3200 Photo
Scanning PolaChrome with Veho VFS-008