I'm finding this document quite useful:
See description of ALTO pasted below, which is a followup to
. We should find a way to convert the transcribed books' HTML to ALTO
Some libraries are apparently using
which seems an augmented
(but unfree?!) version of ScanTailor with some different purpose.
ALTO stores layout information and OCR recognized text of pages of any
kind of printed
documents like books, journals and newspapers. ALTO can detail technical
describing the layout and content of physical resources (text,
ALTO describes a content page with different views:
The Description section helps to describe some general settings and
of the ALTO file (measurement units, file name, etc.), and the
itself (processing steps, software used, dates and actors, etc.)
The Layout section contains what‟s on the page. A page is divided into
regions (print space; left, right, top and bottom margins). For each
objects are listed which have been detected inside: text blocks,
graphical elements, composed blocks. Each object previously identified
by generic attributes: width, height, text content (for the String element).
Besides, the reading order of all the elements can be managed.
Each ALTO file may also contain a style section where different styles (for
paragraphs and fonts) are listed.
ALTO is one of the most common formats used by libraries for converting
images. It‟s used both to deliver digitized contents and to preserve
In a delivery perspective, the ability of ALTO to store the text content
coordinates in a
page allows the overlay of image and text (multilayer PDF) and highlight
in a query.