TILT has now been repackaged as an applet. It can auto-recognise words and lines. The user selects the word or line tool and then clicks on a likely candidate to select it. Also shown are the black and white image (which TILT actually uses to do word and line-recognition), and the view showing the detected baselines.
One thing this does show is that an applet is an excellent form for this application. It is based on a stable and powerful software platform (Java), is delivered over the Web, and facilitates both rapid development and user feedback. Although still far from finished, it is surprising what has been possible in just two weeks.
This works by assessing a small square around the click-point. If this is darker than average then it is added to the selection, otherwise it is subdivided into four smaller squares and reassessed. If either the big or one of the small squares are accepted, then the four big squares to the north, south, east and west are assessed similarly. Word boundaries are thus rapidly identified.
This works by counting up the concentration of black pixels in each row of the image. Anything below the average intensity of the page is ignored. The peaks are mostly baselines.
Although this simple algorithm won't work for slanted or curved lines, I will later subdivide the image into narrow columns and join up the detected baselines. This should overcome the limitation.
There are still a lot of things it doesn't do yet, such as create actual links, or store the results. But, hey, one step at a time.