Jean-Jacques Sacre

Optimal design and critical analysis of a high-resolution video plenoptic demonstrator

A plenoptic camera is a natural multiview acquisition device also capable of measuring distances by correlating a set of images acquired under different parallaxes. Its single lens and single sensor architecture have two downsides: limited resolution and limited depth sensitivity. As a first step and in order to circumvent those shortcomings, we investigated how the basic design parameters of a plenoptic camera optimize both the resolution of each view and its depth-measuring capability. In a second step, we built a prototype based on a very high resolution Red One® movie camera with an external plenoptic adapter and a relay lens. The prototype delivered five video views of 820 × 410. The main limitation in our prototype is view crosstalk due to optical aberrations that reduce the depth accuracy performance. We simulated some limiting optical aberrations and predicted their impact on the performance of the camera. In addition, we developed adjustment protocols based on a simple pattern and analysis of programs that investigated the view mapping and amount of parallax crosstalk on the sensor on a pixel basis. The results of these developments enabled us to adjust the lenslet array with a submicrometer precision and to mark the pixels of the sensor where the views do not register properly.

A metamerism-based method to prevent camcorder movie piracy in digital theaters

This document proposes a new, multi-primary projection system for prevention of illegal recordings in movie theaters. As of today, most camcorder-jamming methods tend to rely on either Infra-Red or spatial/temporal light modulations, both being easy to defeat using an appropriate filter system. Like Infra-Red, a metamerism-based system will modulate light magnitude depending on wavelength, but this time within the range of visible light, making jamming patterns harder to filter out. The mathematical model we use to solve our problem can actually serve as a generic model for all spectrum-based methods, including IR.

55.1: Diversity and Coherence of 3D Crosstalk Measurements

3D crosstalk is a major contributor to 3D quality loss and visual fatigue on stereoscopic displays. This paper presents several 3D crosstalk measurement methods and discusses the coherence between methods, towards the derivation of meaningful quality indicators. It also identifies the need of synthetic indicators for complex crosstalk effects.

Correlation between a perspective distortion in a S3D content and the visual discomfort perceived

Perspective distortion will occur in stereoscopic 3D (S3D) when the relative disparity between elements generates a depth not in accordance with the relative size of the presented objects. Subjective tests have been conducted using test sequences where shooting parameters are perfectly known and where vergence/accommodation conflict is not predominant. Perspective distortions will occur with some of the sequences, depending on viewing conditions. People were asked to qualify sequences in term of naturalness and visual comfort. Results of test revealed a clear correlation between perspective conflict and visual discomfort perceived. Whatever the shooting condition, parallel or toed-in cameras, results are similar. A factor between depth and perspective can be calculated for each shooting configuration and viewing condition. This factor seems a relevant indicator to evaluate the comfort of S3D content perception. Subjective tests allowed to better understand the link between perspective conflicts and visual comfort. Next, studies will be conducted to extend these tests to cinema conditions were the range of viewing conditions is larger.

Optimal design and critical analysis of a high resolution video plenoptic demonstrator

A plenoptic camera is a natural multi-view acquisition device also capable of measuring distances by correlating a set of images acquired under different parallaxes. Its single lens and single sensor architecture have two downsides: limited resolution and depth sensitivity. In a very first step and in order to circumvent those shortcomings, we have investigated how the basic design parameters of a plenoptic camera optimize both the resolution of each view and also its depth measuring capability. In a second step, we built a prototype based on a very high resolution Red One® movie camera with an external plenoptic adapter and a relay lens. The prototype delivered 5 video views of 820x410. The main limitation in our prototype is view cross talk due to optical aberrations which reduce the depth accuracy performance. We have simulated some limiting optical aberrations and predicted its impact on the performances of the camera. In addition, we developed adjustment protocols based on a simple pattern and analyzing programs which investigate the view mapping and amount of parallax crosstalk on the sensor on a pixel basis. The results of these developments enabled us to adjust the lenslet array with a sub micrometer precision and to mark the pixels of the sensor where the views do not register properly.