PUBLIC MARKS with tags compression & jpeg

Aims of the standard: While there is a modest increase in compression performance of JPEG 2000 compared to JPEG, the main advantage offered by JPEG 2000 is the significant flexibility of the codestream. The codestream obtained after compression of an image with JPEG 2000 is scalable in nature, meaning that it can be decoded in a number of ways; for instance, by truncating the codestream at any point, one may obtain a representation of the image at a lower resolution, or signal-to-noise ratio – see scalable compression. By ordering the codestream in various ways, applications can achieve significant performance increases. However, as a consequence of this flexibility, JPEG 2000 requires codecs that are complex and computationally demanding. Another difference, in comparison with JPEG, is in terms of visual artifacts: JPEG 2000 only produces ringing artifacts, manifested as blur and rings near edges in the image, while JPEG produces both ringing artifacts and 'blocking' artifacts, due to its 8×8 blocks. French trad: Objectifs de la norme: Bien qu'il y ait une augmentation modeste des performances de compression de JPEG 2000 par rapport à JPEG, le principal avantage offert par JPEG 2000 est la flexibilité significative du flux codé.

Kraken is a robust, ultra-fast image optimizer and compressor with best-in-class algorithms. We'll save you bandwidth and storage space and will dramatically improve your website’s load times.

Reduce photo file size by up to 5x, without compromising quality

"ImageOptim is a front-end (GUI) for set of tools for optimisation of PNG/JPEG images and GIF animations. Optimisation makes files smaller (in terms of disk space) by finding optimal compression parameters and by removing unneccessary information, like file comments, EXIF tags and color profiles."

Un optimiseur d'image en ligne.

Article très intéressant sur le type d'image à utiliser pour un site web ainsi que les différentes optimisations possibles pour png.