Image and radio-frequency data compression for OPS-SAT using FAPEC

OPS-SAT is an ESA technology demonstration cubesat which includes a colour camera, a Software Defined Radio (SDR) receiver and a powerful ARM processor. One of the experiments executed there is FAPEC, a high-performance and versatile data compression software. Among others, it features image compression and linear prediction coding algorithms, suitable for multi-band and baseband radio-frequency (RF) samples, respectively. Since its deployment on-board OPS-SAT in late 2020, FAPEC has allowed for downloading a large set of Earth Observation images. Recently, thanks to ESA Open Space Innovation Platform funds, these two algorithms from FAPEC are being improved to get better compression ratios and speeds, add video compression capabilities, and higher quality levels in case of lossy compression. A smart lossy approach is being developed for radio-frequency data, identifying the time segments with signal presence and quantizing noise-only samples to further reduce the size. In order to identify the really useful files to be downloaded from the satellite, on-board data analysis capabilities are being developed as well. In this work we present in-orbit results, recent developments and preliminary results obtained with the new algorithms on real data.Peer ReviewedPostprint (published version

Image data compression based of HPA and FAPEC

We present the results of a new compression algorithm, Hierarchical Pixel Averaging (HPA), espcifically designed to compress images. Our results indicate that the compression ratios obtained with HPA are equivalent to those obtained using other standards, like JPEG. Specifically, we introduce the algorithm, its implementation and the several tests done so far on a standard set of images

Image data compression based of HPA and FAPEC

We present the results of a new compression algorithm, Hierarchical Pixel Averaging (HPA), espcifically designed to compress images. Our results indicate that the compression ratios obtained with HPA are equivalent to those obtained using other standards, like JPEG. Specifically, we introduce the algorithm, its implementation and the several tests done so far on a standard set of images

Image data compression based of HPA and FAPEC

We present the results of a new compression algorithm, Hierarchical Pixel Averaging (HPA), espcifically designed to compress images. Our results indicate that the compression ratios obtained with HPA are equivalent to those obtained using other standards, like JPEG. Specifically, we introduce the algorithm, its implementation and the several tests done so far on a standard set of images

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16.00; Translated from Czech (Zvaranie 1987 v. 36 (8) p. 235-238)SIGLEAvailable from British Library Document Supply Centre- DSC:9023.19(VR--3380)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Image data compression with hierarchical pixel averaging and fully adaptive prediction error coder

The fully adaptive prediction error coder (FAPEC) is an entropy coder that typically offers better results than the adaptive Rice compressor. It uses basic preprocessing stages such as delta preprocessing, but it can also be combined with a discrete wavelet transform. We describe a new algorithm called hierarchical pixel averaging (HPA). It divides an image into blocks of 16 x 16 pixels, which are subsequently divided into smaller blocks, up to the basic level where one block corresponds to one pixel. Average pixel values are determined for each level from which differential coefficients are extracted. HPA allows the introduction of controlled losses with several quality levels, also allowing to progressively decompress a given image from lower to higher quality. It achieves better resolution in sharp image edges when compared to other lossy algorithms. HPA is based on simple arithmetic operations, allowing a very simple (thus quick) implementation. It does not use any floating-point operations, which is an interesting feature for satellite or embedded data compression. We present a first implementation of HPA and the results obtained on a variety of images, both for the lossless and lossy cases with different quality levels. Our results indicate that HPA + FAPEC offer a performance comparable to that of CCSDS 122.0. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE

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Il volume intende offrire un bagaglio di tecniche fondamentali ai fini di una corretta applicazione delle norme di diritto civile al caso concreto, secondo un metodo didattico che si ispira alla tradizione giuridica tedesca del c.d. Anspruchmetode, che guida gli studenti a redigere pareri scritti di diritto civile su casi concreti, rispettando uno stile argomentativo logicamente strutturato e orientato alle pretese giuridiche fatte valere dalle parti