No abstract

This paper deals with the representation of spectral data so as to control the colorimetric error committed during rendering computations. These data are projected on a set of hierarchical basis functions called scaling functions leading to a representation by means of binary trees. An adaptive algorithm is proposed in which refinement and merge steps managed by an estimation of the error made in the XY Z color space allows to control the representation of spectra

Due to the improvement of image rendering processes, and the increasing importance of quantitative comparisons among synthetic color images, it is essential to define perceptually based metrics which enable to objectively assess the visual quality of digital simulations. In response to this need, this paper proposes a new methodology for the determination of an objective image quality metric, and gives an answer to this problem through three metrics. This methodology is based on the LLAB color space for perception of color in complex images, a modification of the CIELab1976 color space. The first metric proposed is a pixel by pixel metric which introduces a local distance map between two images. The second metric associates, to a pair of images, a global value. Finally, the third metric uses a recursive subdivision of the images to obtain an adaptative distance map, rougher but less expensive to compute than the first method.

Abstract. This paper presents results of a TFM implementation for Full Matrix Capture acquisitions in CIVA, proposed as a post-processing tool for accurate analysis. This implementation has been made on GPU architecture with OpenCL to minimize the processing time and offer computational device flexibility (GPU/CPU). Examples on immersion configurations on isotropic 2D CAD specimen with planar extrusion are proposed to illustrate the performances. Reconstructions on 2D or 3D areas of direct echoes with mode conversion are allowed. Probe scanning can also be taken into account. Reconstruction results and a benchmark explaining the speedup are presented. Further improvements are also reviewed.

Abstract. Ultrasonic field simulation is a key ingredient for the design of new testing methods as well as a crucial step for NDT inspection simulation. As presented in a previous paper [1], CEA-LIST has worked on the acceleration of these simulations focusing on simple geometries (planar interfaces, isotropic materials). In this context, significant accelerations were achieved on multicore processors and GPUs (Graphics Processing Units), bringing the execution time of realistic computations in the 0.1 s range.In this paper, we present recent works that aim at similar performances on a wider range of configurations. We adapted the physical model used by the CIVA platform to design and implement a new algorithm providing a fast ultrasonic field simulation that yields nearly interactive results for complex cases. The improvements over the CIVA pencil-tracing method include adaptive strategies for pencil subdivisions to achieve a good refinement of the sensor geometry while keeping a reasonable number of ray-tracing operations. Also, interpolation of the times of flight was used to avoid time consuming computations in the impulse response reconstruction stage.To achieve the best performance, our algorithm runs on multi-core superscalar CPUs and uses high performance specialized libraries such as Intel Embree for ray-tracing, Intel MKL for signal processing and Intel TBB for parallelization. We validated the simulation results by comparing them to the ones produced by CIVA on identical test configurations including mono-element and multiple-element transducers, homogeneous, meshed 3D CAD specimens, isotropic and anisotropic materials and wave paths that can involve several interactions with interfaces. We show performance results on complete simulations that achieve computation times in the 1s range.