Jean-Marie Moureaux

Fast zonal DCT-based image compression for Wireless Camera Sensor Networks

This paper deals with image compression over Wireless Camera Sensor Networks (WCSNs) in order to decrease the energy consumption of sensors and thus to maintain a long network lifetime. As the radio tranceiver is the most power greedy components of sensor nodes, it seems natural to consider lossy compression before transmission as the appropriate answer to the problem of energy consumption. However, the limitation of sensor nodes in terms of memory as well as processor speed makes most of the compression algorithms inapplicable. Indeed, the most popular methods such as JPEG or JPEG2000 can yield a higher energy consumption than when transmitting uncompressed images. Here we propose to solve this problem by the design of a fast zonal DCT-based image compression algorithm which allows an efficient tuning of the trade-off between energy consumption and image distortion, as shown by experimental results provided in the paper.

Subjective MPEG2 compressed video quality assessment: Application to Tele-surgery

The digital revolution in medical environment speeds up development of remote Robotic-Assisted Surgery and consequently the transmission of medical numerical data such as pictures or videos becomes possible. However, medical video transmission requires significant bandwidth and high compression ratios, only accessible with lossy compression. Therefore research effort has been focussed on video compression algorithms such as MPEG-2. In this paper, we are interested in determining compression thresholds and associated bit-rates which are acceptable with respect to the quality required in the field of medical video transmission. To evaluate MPEG-2 compressed medical video quality, we performed a subjective assessment test with a panel of human observers (experienced surgeons) using a DSCQS (Double-Stimuli Continuous Quality Scale) protocol derived from the International Telecommunication Union recommendations (ITU-R BT-500-11). Promising results estimate that 3 Mbits/s could be sufficient (compression ratio around threshold compression level around 90∶1 compared to the original 270 Mbits/s) as far as perceived quality is concerned.

Lossy compression of volumetric medical images with 3D dead-zone lattice vector quantization

This paper presents a new lossy coding scheme based on 3D wavelet transform and lattice vector quantization for volumetric medical images. The main contribution of this work is the design of a new codebook enclosing a multidimensional dead zone during the quantization step which enables to better account correlations between neighbor voxels. Furthermore, we present an efficient rate–distortion model to simplify the bit allocation procedure for our intra-band scheme. Our algorithm has been evaluated on several CT- and MR-image volumes. At high compression ratios, we show that it can outperform the best existing methods in terms of rate–distortion trade-off. In addition, our method better preserves details and produces thus reconstructed images less blurred than the well-known 3D SPIHT algorithm which stands as a reference.

Design and performance analysis of a zonal DCT-based image encoder for Wireless Camera Sensor Networks

Systems mapped on CMOS architectures are often expected to achieve high processing bandwidth and low energy consumption. However, a specific care should be paid to adequate the algorithm structure to the circuit architecture when designing multimedia wireless embedded networking systems. This paper addresses the problem of low power consumption and real time constraints for image communication in wireless camera sensor networks (WCSN). It presents a low-complexity hardware implementation of JPEG-like encoder for image compression and paquetization. The designed circuit is planned to be embedded in the camera sensor node to relieve the main processor of the data processing tasks. This encoder combines the best lifting DCT algorithm of the literature with a zonal coding approach. The former reduces the number of operations required per DCT coefficient while the latter reduces the number of coefficients to be computed, quantized and encoded. We study the tradeoff between the size of the zonal mask (a square zone of size k) and the visual image quality as a function of the compression bitrate, then we describe the hardware features of the JPEG-like circuit when implemented on different FPGAs and ASIC prototypes. Performance evaluation is provided for several ranges of compression bitrate, accordingly with the right value of k. Considering a grayscale image compressed to 0.25bpp for example, k=4 is the best choice. In this case, and for an image of 128x128 pixels, the CMOS circuit of the proposed encoder, synthesized using 45nm integration technology, clocks at 360MHz and consumes 18.02mW. It outperforms most of similar circuits being presented in the literature.

FPGA-based image compression for low-power Wireless Camera Sensor Networks

In this paper, a low-complexity image compression scheme for energy-constrained Wireless Camera Sensor Networks (WCSN) is presented and its hardware implementation cost for FPGA solution is evaluated. The main purpose of this FPGA circuit is to relieve the main microcontroller in the camera sensor node of the image compression tasks and to achieve highspeed and low-power image processing. The interest of our hardware solution is twofold. First, a fast zonal DCT algorithm is used to reduce the number of DCT coefficients in each block of the image to be computed, quantized and encoded. Second, compression settings can be changed at runtime in order to allow a dynamic adjustment of the trade-off between energy consumption and image distortion. The efficiency of the image compression scheme is validated through experimental results using FPGA platform.

Compressed image quality assessment: Application to an interactive upper limb radiology atlas

It is admitted that lossy compression can be used in the field of medical images under the control of experts. Lossy compression can offer substantial reduction of the volumes of medical images, being thus an efficient solution for both storage and transmission problem in the medical context. Furthermore, the use of touchpads in medicine has grown and many medical applications on this kind of support is now available. The storage capacity of this kind of terminal is limited, lossy compression represents a good alternative to allow greedy medical applications on such terminals. In this work, we address the problem of quality assessment of MRI scans from an interactive upper limb radiology atlas (Monster Anatomy Upper Limb). The quality assessment protocol is adapted from the International Telecommunication Union recommendations (ITU-R BT-500-11). In this paper, we propose to determine compression thresholds which are acceptable according to the quality required for the proper use of this radiology atlas. We show that this application (using a simple JPEG encoder) has a lossy compression threshold ranging from 13: 1 for the majority of the atlas images up to 27: 1 for the hand images. Finally, several objective image quality assessment algorithms (IQA) are also linked to subjective ratings of the panel of health professionals.

P17.09PCV CHEMOTHERAPY IMMEDIATELY FOLLOWED BY RADIOTHERAPY IN DIFFUSE LOW GRADE GLIOMAS - ABOUT A SERIES OF 12 PATIENTS

INTRODUCTION: PCV (procarbazine, CCNU, vincristine) chemotherapy was the first association evaluated in diffuse low grade gliomas (DLGGs). Impact of temozolomide and PCV was previously assessed on growth kinetics. Nevertheless, there are no data concerning the growth kinetics of DLGGs after PCV immediately followed by radiotherapy. METHODS: We retrospectively selected patients with histological diagnosis of DLGGs from a french neuro-oncological center (Nancy) who benefited from PCV chemotherapy immediately followed by conventional radiotherapy. Clinical, neuroimaging (kinetics), pathological and molecular data were recorded. RESULTS: Twelve patients with a median age at diagnosis of 37,9 years (range 24 to 56) were selected. The median follow-up was 17,9 years (range 12,6 to 22,31). The median number of PCV cycles was 5 (range 2 to 6). The median time between the end of PCV chemotherapy and the beginning of the radiotherapy was 2,6 months (range 1 to 5). The median dose of radiotherapy was 54 Gy (range 54 to 60). During the follow-up period, 3 patients died and 3 patients presented anaplastic transformation (median time to transformation 12 years, range 11,8 to 14). The median survival was 18 years (range 12,6 to “not reached”). 2 patients developed severe neurocognitive deficits (dementia) and 1 patient presented a postradiation stroke. 10 DLGG patients had IDH1 R132H mutation, 5 patients showed a surexpression of P53 and 5 expressed alpha-internexin. Before treatment combining PCV and radiotherapy, the median spontaneous growth kinetics was 4,03 mm per year (range 2,32 to 11,26). After the combined treatment, the growth kinetics remain negative in 10 patients with a median of -1,72mm/year (range -5,36 to 1,92). The median duration of negative kinetics was 8,8 years (range 0 to 16,6). CONCLUSIONS: Despite this limited series, we reported growth kinetics data on the synergy of PCV and radiotherapy in DLGGs. The prolonged response seems longer than previous data obtained with PCV alone (median of 2,7 years). Specific neurocognitive and quality of life data will be collected.