The correct choice of tools for a new Deep Zoom ap

I want to create a new application. It will basically be a Deep Zoom application that users can draw annotations on (that will save to a DB so other users can see those annotations.) At first it will just simply run in a browser. However, the app would be useful if it could be used by enthusiasts in the field, so ability to run on smartphones or other handheld devices would be massively beneficial. 3G/4G signal is likely to be practically non existent in those places, so having the ability to download all the images and info for an "area" would be good.

I can't decide on which technology to use. Silverlight Deep Zoom apps look really nice in browsers, but I have heard that it is not a widely supported technology that MS might be ditching anyway and the only smartphones that would be capable of running Silverlight would be Windows phones = a very small share of the smartphone market. Flash will probably never run on iPhones/Apple products in general. So should I use HTML5? HTML5 all seems a little confusing to me at the moment, would it even be possible to make a HTML5 Deep Zoom application that users could annotate?

Any thoughts and advice would be really handy, thanks for reading.

I wrote a Deep Zoom app that supported annotation for a proof of concept a couple of years ago.

I used Django for this, however it is not approach I would recommend. If i was doing the same job again I would use CanvasZoom, which is based on HTML5. Canvas Zoom can be embedded into a webpage through javascript. There is a guide on how to do this here:

a link

Unfortunately you need to run Microsoft DeepZoom composer on the original image first in order too generate the deep zoom data that CanvasZoom will use. If you want your app to run in a browser it is likely that you will have to go for the following approach.

User selects image.
Image gets uploaded to server
Server creates deep zoom information
Use a PHP based approach so you have a canvaszoom page for the image.

The annotations will probably complicate matters, I did this with javascript when I attempted it. The trick is to work out when the image has been zoomed in (with canvas zoom there are preset zoom levels) and redraw the annotation regions. I found this approach non-trivial but not overly complicated.

Canvas Zoom is MIT licensed, so you can do what you like with it.

Good luck with your project.