Jean-Jacques Bourdin

Fast Lines: a Span by Span Method

Straight line’s scan conversion and drawing is a major field in computer graphics. Algorithm’s time computation is very important. Nowadays, most of research papers suggest improvements of the DDA method that was first presented by J. Bresenham. But other approaches exist as well like combinatory analysis and linguistic methods. Both of them use multiple string copies that slow down the efficiency of the algorithms. This paper proposes a new algorithm based on a careful analysis of the line segments’ properties some of them previously unused. Our algorithm is proved significantly faster than previously published ones.

From Detail to Global View, an Impressionist Approach

This paper presents a new method for zooming out an image. As the Impressionism is one of the most complete painting technique, able to preserve notably details, light effects at a close or far range, we propose a method based on an impressionist approach. The input image is analyzed and described through impressionist characteristics that will be preserved when a zoom out will be realized. We created a set of characteristics of images and the corresponding algorithms to compute them. These characteristics are then used to build a set of zooming out algorithms. To validate the process, the zooms out have been applied to different types of images: photographs of paintings and other photographs. Results prove that this approach is more suitable than existing ones.

Zooms arrières, une approche impressionniste

This paper presents a new method for zooming out an image. As the Impressionism is one of the most complete painting technique, able to preserve noticeable details and light effects, the method proposed in this paper is based on an impressionist approach. The input image is analyzed and described through impressionist characteristics that will be preserved when a zoom out will be realized. These characteristics are computed and used to build a set of zooming out algorithms. By opposition to the zoom-out implemented in image manipulation softwares that compute a new color for each pixel of the resulting image (by an average or an interpolation), our zoom-out process uses only existing colors in the original image to create the resulting image. To validate the process, the zooms out have been applied to different types of images: photographs of paintings and other photographs. Results prove that this approach is more suitable than existing ones. MOTS-CLES : Traitement numerique des images, Perception visuelle, rendus expressifs, methodes impressionnistes.