Blockwise discrete Fourier transform analysis of digital hologram data of three-dimensional objects

Abstract

We report on the results of a study into the characteristics of the blockwise discrete Fourier transform (DFT) coefficients of digital hologram data, with the aim of efficiently compressing the data. We captured digital holograms (whole Fresnel fields) of three-dimensional (3D) objects using phase-shift interferometry. The complexvalued fields were decomposed into nonoverlapping blocks of 8 × 8 pixels and transformed with the DFT. The inter-block distributions of the 64 Fourier coefficients were analyzed to determine the relative importance of each coefficient. Through techniques of selectively removing coefficients, or groups of coefficients, we were able to trace the relative importance of coefficients throughout a hologram, and over multiple holograms. We used rms error in the reconstructed image to quantify importance in the DFT domain. We have found that the positions of the most important coefficients are common throughout four of the five digital holograms in our test suite. These results will aid us in our aim of creating a general-purpose DFT quantization table that could be universally applied to digital hologram data of 3D objects as part of a JPEG-style compressor.

Extended focused imaging for digital holograms of macroscopic three-dimensional objects

“…The large file sizes of DHs have led to research into their compression for the purpose of efficient storage and transmission [12]. The research has focused on compression of the complex field at the hologram plane [5,[12][13][14][15] and the reconstruction plane [16]. Digital holographic reconstructions also suffer from speckle noise, a noise that is inherent in any optical system using coherent light.…”

Focused image creation approaches for macroscopic objects encoded in digital holograms

“…The large file sizes of DHs has lead to research into their compression for the purpose of efficient storage and transmission. 12 The research has focused on compression of the complex field at the hologram plane 5,[12][13][14][15] and the reconstruction plane. 16 Digital holographic reconstructions also suffer from speckle noise, a noise that is inherent in any optical system using coherent light.…”