Exact global motion compensation for holographic video compression

Abstract

Holographic video requires impractical bitrates for storage and transmission without data compression. We introduce an end-to-end compression pipeline for compressing holographic sequences with known ground truth motion. The compression strategy employs a motion compensation algorithm based on the rotational transformation of angular spectrum. Residuals arising from the compensation step are represented using short-time Fourier transforms and quantized with uniform mid-rise quantizers whose bit depth is determined by a Lagrangian rate-distortion optimization criterion where the distortion metric is the mean squared error. Experiments uses computer generated holographic videos and we report Bjøntegaard delta peak signal to noise ratio gains of around 20 dB when compared to traditional image/video codecs.

Phase space formulation of light propagation on tilted planes

“…The wavefield 𝜓 after propagation is defined as the solution to the Helmholtz equation in 3D space with initial conditions 𝜓 0 in a given plane 𝑃. A convenient way to express this solution is provided by the angular spectrum representation [1]; for 𝑟 ∈ R 3 ,…”

“…When it comes to non-parallel planes, a convenient way to extend the solution to Helmholtz equation is by using the angular spectrum expression of the propagation operator. The study of the adaptations to be brought to this operator for handling tilted planes has first been done by Matsushima [2], which has been successfully used in practical optics applications [3] and remains the reference formulation in frequency domain. However, for many applications, namely related to hologram generation, compression and adaptive display, it is required to work in the so-called phase space, i.e.…”

Compression strategies for digital holograms in biomedical and multimedia applications

“…Indeed, because of the non-local nature of holographic signals, classical motion estimation and compensation algorithms based on block matching are inefficient to compress hologram sequences, especially those belonging to visualization usecases. In 83 , a motion compensation solution based on a paraxial approximation was proposed for holograms featuring a singular object. In 84 , a motion compensation solution for holography based on the rotational transformation of wavefields 85 was used, where the residuals were further compressed using a STFT transform with an adaptive quantizer, and gains were demonstrated exceeding 20 dB over HEVC.…”

Providing a Visual Understanding of Holography Through Phase Space Representations

“…Several contributions by the authors have made use of phase space methods, too, e.g., for compression [27][28][29]; segmentation of holograms with multiple occluding objects [30]; faster computer generation [31]; development of more efficient propagation schemes [32]; comparison of angular and spatial multiplexed spatial-light modulator setups [33] and the study of their perceptual quality [34]; or to design orthoscopic display setups [35]. Despite this certainly non-exhaustive list of references it is evident how important phase space analysis and PSRs are in optics in general and in DH especially.…”

“…Figure 12e. The exact modifications due to rotations [29,55] around x and y axes for large angles are more difficult to interpret in phase space, as they involve resampling in Fourier space.…”