Accessing scanner at client side from a web page without applet

Atalasoft has a web scanning toolkit that should meet your needs: Atalasoft WingScan product page

The product does not use browser-specific plugins and therefore works nicely in all modern browsers (IE8+, Chrome, Firefox).

Architecturally, there is a small local component that should be installed, which exposes RESTful web service. Web page uses standard JavaScript/jQuery to communicate with the service and scan/import/enhance images.

Here is the online demo, so you could try it out right away: Wing Scan Demo page

The scanning component is based on the EZTwain library, and it includes a number of image processing algorithms that improve quality of scanned images (deskew, autorotate, blank page detection, etc.)

You can optionally license and use embedded VRS technology, which I have to say is impressively good at cleaning up scans.

For client-side you'll want to use Dynamic Web TWAIN. Unfortunately there are no other solutions, but this one is well maintained and documented. The technology for scanners in browsers isn't quite there yet. Read up some of the other posts on Stack Overflow regarding the same web scanning issues here. There's been almost a year's worth of discussion on exactly this topic.

HTML was not capable of it in general before (for security issues, not access to the OS), but this is changing.

HTML 5 has now meany features.

See that post with very detailed informations: Can HTML5 communicate with peripherals like scanners and credit card readers?

In particular, you should focus on camera/video capabilities, which can work for scanners too: http://www.w3.org/TR/2012/WD-mediacapture-streams-20120628/