http://diveintohtml5.info/canvas.html – (уголки)
http://habrahabr.ru/post/111385/ CANVAS шаг за шагом !!!
http://www.websanova.com/blog/html5/10-shapes-to-extend-html5-canvas#.U0ao51fBeKU 10 Shapes to Extend HTML5 Canvas
You may have seen programs like Zoomify, OpenZoom and DeepZoom which quickly display large resolution images – only the part which is needed is downloaded. Most of these use some kind of plugin (e.g. Flash, Silverlight), CanvasZoom does this with only the HTML5 standards. Create your own
The backend part of the system simply consits of several folders full of images of different resolution. The images are most easily generated by the DeepZoom Composer program created by Microsoft, there's also lots of information about the format here. The DeepZoom Composer program currently only works on windows but once you've download it you can create your own zoom images, very quickly.