UnCurve: Lens distortion correction for large format prints
"I had Itzhak apply this workflow to a series of 4x8' 2-flip lenticular prints I made for a recent project. This was using ... 20 LPI which was especially distorted on the ends - so much so that the full size sheets were unusable as they were. They came out great - actually made the project possible, otherwise I am not sure what would have happened... This process is one of the more interesting/useful developments to come down the lenticular pike in some time, in my opinion, solves a real problem."
Fringe pattern before correction
Fringe pattern after correction
When you interlace a sequence of solid color images, the lenticular picture should display a solid color (which will change with the viewing angle). In large format, the picture will often display two or more colors simultaneously. We call such a picture "fringe pattern". Multi-color fringe patterns occur due to distortions in the lenticular lens grid. Such distortions destroy the quality of the picture, and in extreme cases make it unviewable. An extremely distorted fringe pattern is shown on the left-hand side above.
Lenticular sheet manufacturers make great efforts to control the magnitude of the distortions, but for large lenses, this becomes a difficult technological challenge. But there exists another solution: to measure the lenticular grid distortions and warp the interlace accordingly. With this approach, it is possible to create nearly perfect pictures regardless of the lens distortions.
The UnCurve method is a two-step procedure: (1) Measurement, (2) Correction. In the first step, the fringe pattern is used to measure the lens distortions. The second step applies digital warping to the interlace according to the measured distortions. In the above example, the right-hand side shows the fringe pattern of the corrected interlace. The same lens was used in both pictures.
Encountered a distorted lens? Do not trash it; try UnCurve for free!