Université de Neuchâtel

A Numerical Minimization of Perceptual Error for the Linear Chromatic Adaption Transform

Costantini, Roberto ; Ansorge, Michael ; Bracamonte, Javier ; Pellandini, Fausto

In: Proceedings of First European Conference on Colour in Graphics, Imaging, and Vision (CGIV), 2002, p. 164-169

In this paper,new sensors for the chromatic adaptation transform (CAT)are found.They have been obtained by the independent numerical minimization of 6 perceptual error metrics over 16 corresponding color pair (CCP)data sets,including Lam's set,using as starting point for the minimization 4 known and commonly used sensors.An analysis of their performances has shown that the best performance is...

Université de Neuchâtel

Design Methodology for VLSI Implementation of Image and Video Coding Algorithms – A Case Study

Bracamonte, Javier ; Ansorge, Michael ; Pellandini, Fausto

In: Intelligent Methods in Signal Processing and Communications, 1997, vol. 14, p. 1-20

In this chapter a methodology for the design of VLSI circuits for image and video coding applications is presented. In each section a different phase of th edesign procedure is discussed, along with a description of the involved software environments. An example of an area efficicient single-chip implementation of a JPEG coder is presented to illustrate the methodology.

Université de Neuchâtel

Adaptive color image compression based on visual attention

Ouerhani, Nabil ; Bracamonte, Javier ; Hügli, Heinz ; Ansorge, Michael ; Pellandini, Fausto

In: Proceedings of the 11th International Conference on Image Analysis and Processing (ICIAP), 2001, vol. 11, p. 416-421

This paper reports an adaptive still color image compression method which produces automatically selected ROI with a higher reconstruction quality with respect to the rest of the input image. The ROI are generated on-the fly with a purely data-driven technique based on visual attention. Inspired from biological vision, the multicue visual attention algorithm detects the most visually salient...

Université de Neuchâtel

Color Image Compression with a Variable Block-Size Transform Scheme

Bracamonte, Javier ; Ansorge, Michael ; Pellandini, Fausto

In: Proceedings of the International COST 254 Workshop on Intelligent Communication and Multimedia Terminals, 1998, vol. 254, p. 7-10

In a previous paper an adaptive transform-based coding method was introduced and used for the particular application of compressing the monochrome images of video conference sequences [1]. In the present paper the results of applying this adaptive scheme to compress still color images are presented. The basic principle of the algorithm is to encode those larger 2N x 2N -pixel regions featuring...

Université de Neuchâtel

Countering illumination variations in a video surveillance environment

Costantini, R. ; Ramponi, Gianni ; Bracamonte, Javier ; Piller, Bernhard ; Ansorge, Michael ; Pellandini, Fausto

In: Proceedings of the “Nonlinear Image Processing and Pattern Analysis XII”, 2001, vol. 4304, p. 85-97

In the field of video technology for surveillance applications it is often necessary to cope with the phenomenon of illumination variations. In fact, if not compensated, such variations can falsely trigger the change detection module that detects intrusions in video surveillance systems, thus affecting their reliability. Many studies have been made to solve the change detection problem under...

Université de Neuchâtel

VLSI systems for image compression : a power-consumption/image-resolution trade-off approach

Bracamonte, Javier ; Ansorge, Michael ; Pellandini, Fausto

In: Proceedings of the conference “Digital Compression Technologies and Systems for Video Communications”, 1996, vol. 2952, p. 591-596

Low power consumption is a requirement for any battery powered portable equipment. When designing ASICs for image and video compression, emphasis has been placed mainly on building circuits that are fast enough to satisfy the high data throughput associated with image and video processing. The imminent development of portable systems featuring full multimedia applications, adds the low-power...

Université de Neuchâtel

A low-complexity video coder based on the Discrete Walsh Hadamard Transform

Costantini, R. ; Bracamonte, Javier ; Ramponi, Gianni ; Nagel, Jean-Luc ; Ansorge, Michael ; Pellandini, Fausto

In: 10th European Signal Processing Conference EUPSICO, 2000, p. 1217-1220

This paper reports the results obtained of applying the Discrete Walsh-Hadamard Transform (DWHT) in a video coding scheme. It will be shown that for low bitrate applications the DWHT can reach performances analogous to those obtained with the Discrete Cosine Transform (DCT) in terms of compression efficiency, PSNR, and visual quality. This suggests the use of the DWHT in video coding systems...

Université de Neuchâtel

A multiplierless implementation scheme for the JPEG image coding Algorithm

Bracamonte, Javier ; Stadelmann, Patrick ; Ansorge, Michael ; Pellandini, Fausto

In: Proceedings of the “IEEE Nordic Signal Processing Symposium NORSIG 2000”, 2000, p. 17-20

This paper reports an efficient implementation scheme for a JPEG encoder. The baseline JPEG algorithm is executed without involving any multiplication. All the arithmetic operations are reduced to simple additions/subtractions and very short shifts. This translates into a hardware implementation of reduced complexity, which makes this approach attractive in digital image applications for portable...

Université de Neuchâtel

Adaptive block-size transform coding for image compression

Bracamonte, Javier ; Ansorge, Michael ; Pellandini, Fausto

In: Proceedings of the International Conference on Acoustics, Speech, and Signal Processing (ICASSP97), 1997, vol. 4, p. 2721-2724

In this paper we report the results of an adaptive block-size transform coding scheme that is bascd on the sequential JPEG algorithm. This minimum information-overhead method implies a transform coding technique with two différent block sizes: N x N and 2N x 2N pixels. The input image is divided into blocks of 2N x 2N pixels and each of these bocks is...