Prof. Antonio M. G. Pinheiro Profile

Prof. Antonio M. G. Pinheiro

Associate Professor at Univ da Beira Interior

SPIE Involvement:

Author

Publications (10)

Proceedings Article | 17 May 2022 Paper

Definition of common test conditions for the new JPEG pleno holography standard

Antonio M. Pinheiro, Joao Prazeres, Antonin Gilles, Tobias Birnbaum, Raees Kizhakkumkara Muhamad, Peter Schelkens

Proceedings Volume 12138, 121380N (2022) https://doi.org/10.1117/12.2624499

KEYWORDS: Holograms, Holography, Visualization, Signal to noise ratio, Metrology, Image compression, Information visualization, Standards development, Objectives, Holographic interferometry

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Proceedings Article | 6 September 2019 Paper

An exploratory study towards objective quality evaluation of digital hologram coding tools

Roberto Corda, Antonin Gilles, Kwan-Jung Oh, Antonio Pinheiro, Peter Schelkens, Cristian Perra

Proceedings Volume 11137, 111371D (2019) https://doi.org/10.1117/12.2528402

KEYWORDS: Holograms, Digital holography, Signal to noise ratio, Holography, 3D image reconstruction, JPEG2000, Computer generated holography, Image resolution, Microscopy

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Proceedings Article | 17 September 2018 Presentation + Paper

Analysis of motion vectors and parallel computing in pseudo-sequence based light field image compression methods

Hadi Amirpour, Antonio Pinheiro, Manuela Pereira, Mohammad Ghanbari

Proceedings Volume 10752, 107520C (2018) https://doi.org/10.1117/12.2320663

KEYWORDS: Video, Image compression, Video compression, Motion estimation, Parallel computing, Motion analysis, Cameras, Motion models, Computer programming, Raster graphics

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Proceedings Article | 17 September 2018 Presentation + Paper

JPEG Pleno: a standard framework for representing and signaling plenoptic modalities

Peter Schelkens, Zahir Alpaslan, Touradj Ebrahimi, Kwan-Jung Oh, Fernando Pereira, Antonio M. Pinheiro, Ioan Tabus, Zhibo Chen

Proceedings Volume 10752, 107521P (2018) https://doi.org/10.1117/12.2323404

KEYWORDS: Holography, Clouds, Image compression, Standards development, Image processing, Visualization, Image quality standards, Databases, Computer programming, Holograms

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Proceedings Article | 17 September 2018 Presentation + Paper

Point cloud subjective evaluation methodology based on reconstructed surfaces

Evangelos Alexious, Antonio M. Pinheiro, Carlos Duarte, Dragan Matković, Emil Dumić, Luis da Silva Cruz, Lovorka Gotal Dmitrović, Marco Bernardo, Manuela Pereira, Touradj Ebrahimi

Proceedings Volume 10752, 107520H (2018) https://doi.org/10.1117/12.2321518

KEYWORDS: Clouds, Visualization, 3D displays, Video, 3D visualizations

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Proceedings Article | 17 September 2018 Presentation + Paper

A digital hologram compression scheme for representation on the object plane

Marco Bernardo, Elsa Fonseca, Paulo Fiadeiro, António Pinheiro, Manuela Pereira

Proceedings Volume 10752, 107520J (2018) https://doi.org/10.1117/12.2323442

KEYWORDS: Holograms, Digital holography, Holography, Computer generated holography, Image compression

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Digital holography is a growing field that owes its success to the provided three-dimensional imaging representation. This is achieved by encoding the wave field transmitted or scattered by an object in the form of an interference pattern with a reference beam. While in conventional imaging systems it is usually impossible to recover the correct focused image from a defocused one, with digital holography the image can be numerically retrieved at any distance from the hologram. Digital holography also allows the reconstruction of multiple objects at different depths. In a previous study, the benchmark of the main available image coding standard solutions JPEG, JPEG-XT, JPEG 2000 and the HEVC intra mode was performed for digital holographic data represented on the object plane. The HEVC intra main coding profile outperforms the other standards while JPEG 2000 results in very similar compression performance. In the current work, a scheme based on the HEVC intra mode codec for holographic information compression on the object plane is proposed. In the base layer, a 2D version of the object (amplitude information on object plane) is coded with HEVC intra main coding profile. Previously was observed that the phase information requires much higher bit rates than the amplitude information, as standardized codecs are not adapted for the compression of this type of information. In this paper we propose a model where the amplitude information is encoded with the HEVC intra mode codec, while the phase is represented by encoding the real information and the signal of the imaginary information. The real information is also encoded using the HEVC intra mode as it already revealed appropriate for compression of this type of information. The imaginary information signal is encoded with JBIG. The advantage of this scheme is that the amplitude information provides a direct 2D representation of the hologram while the phase information can be considered as a 3D enhancement layer. The results show that the proposed scheme outperforms the state of the art in holography compression, while allowing compatibility with the current standards and direct 2D visualization.

Proceedings Article | 24 May 2018 Presentation + Paper

Benchmarking coding standards for digital holography represented on the object plane

Marco Bernardo, António M. Pinheiro, Manuela Pereira

Proceedings Volume 10679, 106790K (2018) https://doi.org/10.1117/12.2315361

KEYWORDS: Holograms, Digital holography, Holography, Image compression

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The complex object field at the hologram plane can be separated on real and imaginary, or amplitude and phase components for further compression. It could be inferred that more inter-component redundancies exist in real and imaginary information than in the amplitude and phase information. Also, several compression schemes, like lossless compression, lossy compression, based on subsampling, quantization, and transformation, mainly using wavelets were considered. The benchmark of the main available image coding standard solutions like JPEG, JPEG 2000, and the intra coding modes available on MPEG-2, H264/AVC and HEVC video codecs were also analyzed for digital holographic data compression on the hologram plane.

In the current work, the benchmark of the main available image coding standard solutions JPEG, JPEG-XT, JPEG 2000 and the intra mode of HEVC, are performed for digital holographic data represented on the object plane, instead of the hologram plane. This study considers Real-Imaginary and Amplitude-Phase representations. As expected Real, Imaginary and Amplitude information present very similar compression performance and are coded very efficiently with the different standards. However, the phase information requires much higher bitrates (3/4 bpp more) to reach similar quality levels. Moreover, the Amplitude information results in slightly larger bitrates for the same quality level than real or imaginary information.

Comparing the different standards, the HEVC intra main coding profile is a very efficient model and outperforms the other standards. Furthermore, JPEG 2000 results in very similar compression performance. A comparison with studies where coding was performed on the hologram plane will reveal the advantages of coding on the object plane. Hence, becomes evident that future representation standards should consider the representation of digital holograms on the object plane instead of the hologram plane.

Proceedings Article | 15 May 2014 Paper

Automatic face recognition in HDR imaging

Manuela Pereira, Juan-Carlos Moreno, Hugo Proença, António M. Pinheiro

Proceedings Volume 9138, 913804 (2014) https://doi.org/10.1117/12.2054539

KEYWORDS: High dynamic range imaging, Facial recognition systems, Visualization, Time multiplexed optical shutter, Associative arrays, Information visualization, Detection and tracking algorithms, Databases, Imaging systems, Cameras

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