LowBrowse Installation and Documentation

LowBrowse is an innovative experimental way for those with low vision to access text on the web, embodied in a Firefox extension. LowBrowse works only on Firefox versions 3.0-3.6, and has not been supported since Firefox adopted a new product life cycle policy, in which twelve major version numbers of the product have been released in less than two years (at the time of writing Firefox is now up to version 16!). LowBrowse still works fine on the Firefox 3.0-3.6, but if you install it, please be aware that you will not benefit from recent security and other enhancements. You'll need to know the basics of Firefox use to use LowBrowse most effectively, but Firefox is very easy to learn and use if you have experience with any other browser. LowBrowse, like Firefox, runs on Windows, Macintosh, and Linux, but some details of its configuration and operation are different on the three platforms. Here is a screen shot:

LowBrowse Screen Shot

Installation and Quick Start

  • Make sure that you have Firefox version 3 to 3.6 installed on your machine. You'll need to do this before downloading the LowBrowse extension. You can download and install Firefox 3.6 from this page.
  • Download and install the LowBrowse add-on from the Mozilla addons page. The most up-to-date version is 1.0.
  • At the top of the Add-ons window is a button on the right to Restart Firefox. Click on it.
  • Wait for Firefox to restart. At this point LowBrowse will be installed and running. On the Mac version, you may be asked whether "LowBrowse_tts" may connect. Answer "yes".
  • Almost all of LowBrowse's keystroke commands consist of an accelerator key + Alt + <some letter>. On Windows and Linux, the accelerator key is the Ctrl (control) key; on the Mac, it is the Command (or Apple) key.  Here we'll just call it the Accel key.
  • Can you read the large text at the top of the browser window? If so, you can go right to the Quick Help tab by pressing the Accel + Alt + H. That is, press one of the following key combinations, depending on whether you are on Windows, Linux, or Mac OS X:
    • Windows and Linux: Press Control+Alt+H
    • Mac OS X: Press Command+Alt+H
    If you cannot read that text, you will need to configure the text in the top window for the first time.
  • To configure LowBrowse's reading frame parameters for the first time, press Accel+Alt+C. Observe the large text at the top of the browser window. This text is customizable. To see options for the text, press the + (plus) or - (minus) key. When you are satisfied, register your choice with the <Enter> key, and configure your next parameter. With some parameters, such as text size, pressing + enlarges, while pressing - makes it smaller. The Easy Config procedure brings you through selections of
    1. Text size
    2. Color scheme
    3. Font
    4. Letter spacing

Getting help

LowBrowse's Quick Help is a page that appears in a new browser tab that contains all of LowBrowse's commands in summary form. These are reproduced here for the platform which you are currently running.

Function Keys/Mouse Description
Reading text Left « and Right » arrows Scroll text in the reading frame to allow you to read an entire text chunk (most often, a paragraph).
Enlarge image Ctrl+Mouse-wiggle Sends image to zoom window. Up/down arrows further increase or decrease size. Esc or click in main window to exit.
Hide Toolbars and statusbar Accel + Alt + B toggles visibility of toolbars and status bar
Easy Configuration Accel + Alt + C Configures text parameters for the reading frame.
Help Accel + Alt + H opens this Quick Help (with button access to tutorial manual) in a new tab. Esc to exit.
Speak Accel + Alt + S toggles speech
Hide Reading frame Accel + Alt + R toggles visibility of the Reading frame.
Go to new Location Accel + Alt + L enter a new Location (URL) to navigate to.

There is also a more in-depth tutorial LowBrowse user manual that is built into LowBrowse. To access the manual, press the button at the bottom of the Quick Help page. Much of the information in the manual is duplicated here.

How to use LowBrowse

In the LowBrowse way of browsing, there are two views of a web document at all times. The global frame, always shown in the lower part of the browser window, displays the web document at a relatively unmagnified scale (but see this note). The reading frame, always shown just above the global frame, displays text in the vicinity of the mouse cursor position in the global frame. This text is not a magnified image of the text in the global frame. Rather, it is re-rendered in a single, consistent way, in a manner that you can configure once for all web pages you view with your browser.

Even though you may not be able to read the text or see fine details of pages in the global frame, you can use whatever vision you have to locate big features of the page such as paragraphs, lists, navigation bars, images, and the like. The features that are visible to you are the main landmarks you will have for navigating around on the page (not unlike the large landmarks in the environment that you use to navigate while walking).

Reading text

LowBrowse shows you text from your main browser window (the global frame) in the reading frame. To see LowBrowse in action, just move your cursor around over some text.

When you position the cursor over some text using the mouse cursor, the text in the vicinity of the cursor (we call this a text chunk) is simultaneously displayed in the reading frame. Style features that are likely to indicate emphasis, such as italics and boldface, are duplicated in the reading frame, but text color and background color are filtered the text without sacrificing meaning. This is the most basic way to use LowBrowse. The very best way to see how LowBrowse works is to experiment with it.

The reading frame is configurable. Using LowBrowse's Easy Configuration, you can select from among several highly visible fonts, font sizes, text color schemes, and inter-letter spacings. And with Advanced Configuration, you can select these with almost unlimited flexibility.

Observe that the reading frame shows only the first words from the text chunk (often a paragraph, a heading, or a table cell) that your cursor is hovering over. To see more of the text from the paragraph, press the Right-arrow key. You may also go back within the text chunk by pressing the Left-arrow key. Effective use of LowBrowse requires understanding two essential things:

  1. The words you see in the reading frame are not always the words directly under your cursor. You will often have to use the arrow keys to see all of the text. How much you have to press the arrow keys depends on how much text fits in the reading frame.
  2. When the mouse cursor is over text within a paragraph that is in italics or boldface, you will generally have access only to that text in the reading frame, and not to the entire paragraph. To see the entire paragraph or text chunk, simply move the mouse off to normal, unbolded, unemphasized text. Note that this is true only within paragraphs or other text chunks--it does not apply to headings.

Links, we should mention, are always displayed in a special link color, so that you know which text is clickable, but it is a single, consistent link color that contrasts well against its background. It's important to know that the reading frame is just for display. All actions, including clicks and text input (see this section), are peformed in the global frame.

Because LowBrowse shows you only the beginning words of text chunks, it is ideal for skimming a web page to look for information. It may take a bit of practice before you can do this efficiently.

Viewing Images

How does LowBrowse handle images? When your mouse cursor is over an image, you will see "IMG:" in the reading frame, followed by whatever description (Alt-text) of the image the web author placed in the document for the benefit of those who might not be able to see images (such as blind persons).

LowBrowse also allows you to enlarge most images. To see an image enlarged, hold down the Ctrl key and wiggle the mouse over the image. A large-size version of the image (default zoom is 3X) will pop up, which you may further enlarge by pressing the Up-arrow key (or shrink with the Down-arrow key). To make this enlarged image disappear, press the Escape key, or click anywhere in the main browser window.

It is important to recognize that not all images look like images. Many web pages have images that contain text, and that sometimes, you might see something that looks like text that is actually an image containing text. You can magnify such "pictures of text" using this Ctrl-wiggle technique just described, to help you see what text is rendered in them.

Text input

Using the reading frame as an input field:

LowBrowse gives you access to your own input text in text input fields as well. Simply hover the mouse over a text input field (such as you see commonly in search boxes). When you do so, the reading frame will reverse its foreground and background colors, and any letters you type will appear there. When you are done, press <return> and the text you input is transferred to the text input field in the global frame.

Since you may not be inclined to share your passwords in large print with whomever is in the vicinity of your computer, LowBrowse uses masking characters for password fields, to help maintain security of your accounts.

Navigating to new locations

The reading frame also can act as a location bar from which you can navigate to other web sites. Pressing Accel + Alt + L opens the reading frame as a URL-input field, where you can type in a URL that you want to navigate to directly. As with text input fields, the colors reverse to let you know you are in "input" mode.

Want speech output? LowBrowse talks, which may be helpful if you have very low vision, or if you would rather listen to long paragraphs rather than repeatedly pressing the Right-arrow key. A nice feature of the speech is that you don't have to wait for it to finish a sentence or paragraph before moving on. Once the cursor has moved to a new text chunk, speech from the old chunk abruptly turns off, and LowBrowse immediately speaks the new text. This is particularly useful for skimming and searching for information.

A quick note about voices. Voice quality depends on which platform you are running on and which speech software you have installed. In our opinion, Windows Vista and Mac OS X provide the most natural sounding voices that are included with the operating system software. Windows XP and the FreeTTS voices are of lower quality but are still quite intelligible and usable.

Quick Help

Accel + Alt + H opens a new tab with concise reminders of all of LowBrowse's keystroke commands, along with buttons for closing that tab or opening this tutorial manual page.

Helpful Firefox features to use in conjunction with LowBrowse

  • Page zoom (Accel + +, Accel + -). These commands increase and decrease overall zoom (magnification) of the main page. Depending on your visual ability to identify features on the main page such as paragraphs, images, navigation bar, etc., you may want to adjust overall zoom somewhat.To return to normal zoom, use Cmd + 0.
  • Ctrl + Tab (forward) and Ctrl + Shift + Tab (backward) display pages in other Firefox tabs.
  • View Toolbars and View Status bar. Most users will want to uncheck these so that these bars, which take up valuable screen real estate, are not visible.
  • View Fullscreen (F11). This command, available in the Windows version of Firefox, maximizes screen real estate devoted to Firefox in a single command. It is a toggle, so pressing F11 again brings back the toolbars and menubars.

Easy Configuration

Pressing Accel + Alt + C brings up LowBrowse's Easy Configuration procedure. With a fixed but limited repertoire of parameter values, it allows configuration that should work well for any users that LowBrowse is appropriate for. The procedure runs through simple choice of font size, color scheme, font family, and letter spacing (for each, see the choices by by pressing + or -; select by pressing <enter>.

Advanced Configuration

The simple configuration procedure called up by Accel + Alt + C allows only a limited choice of configuration parameters. These are certainly sufficient for most users and are chosen for a high degree of visual accessibiity. To select fonts othere than Courier New, Times Roman, Verdana, or Arial, to create other color schemes, or to fine tune the letter spacing or font size, you can adjust parameters using the Firefox preferences facility. To do this, type "about:config" in the location bar, and type "lowbrowse" into the filter field. All parameters starting with "extensions.lowbrowse" can be configured there.

Large cursors

LowBrowse is most useful in conjunction with a large cursor, one that you are comfortable using and can see sufficiently clearly to be able to be able to position over elements of the web document that you are interested in seeing better. Large cursors are operating system-dependent.

  • Mac OS X: Macintosh users (OS X and above) will be comfortable using a cursor that can be enlarged in the Universal Access screen, accessible through the System Preferences facility of OS X. Select the Mouse & Trackpad screen and adjust the cursor size with the slider near the bottom of the screen.
  • Windows XP and Vista Ordinary Windows cursors are limited to 32 x 32 pixels, however, using software such as that from Stardock.com , one can install much larger cursors. Therefore, Windows users will probably want to use a program such as Stardock's free (but not open source) program CursorXP, which you can download right here, or their more flexible program CursorFX. Here is a large cursor we designed for LowBrowse that works with CursorXP and should work with CursorFX. It should install automatically if you have either of the Stardock cursor programs already installed. To toggle the large cursor on and off, use Shift + Ctrl + C.
  • Linux: Linux users have several options that are specific to the desktop environment they are running (e.g. GNOME or KDE), or they may edit ~/.Xdefaults and enter a cursor size such as
    Xcursor.size: 64

    Following this, they must run
    xrdb -m ~/.Xresources

Frequently Asked Questions

Does LowBrowse work with Firefox tabs?

Yes, though occasionally, when switching back and forth between tabs, you may have to reload the page (using the Firefox command Accel - R) to get LowBrowse back in sync with a particular tab's content.

How does LowBrowse handle new window and tabs?

LowBrowse automatically adds a reading frame to any new windows generated. However, turning off the reading frame with Accel + Alt + R works only on the currently active window.

What improvements are you working on for the future?

There are certain kinds of content that are not handled well, and in some cases, at all, in LowBrowse, including Flash content, and many embedded objects. We are working to improve access to these. We are also planning to add a way to acces history and bookmarks. Finally, we are working on a way to make it easier to visualize the scope of the text chunks that are displayed in the reading frame in the main browser window. Stay tuned.

What are some of Lowbrowse's quirks and issues?

  • Initially you may feel that the fact that the Reading Frame displays words that are not necesarily under the mouse cursor is a quirk, but you will soon get used to this and to using the arrow keys to access longer text strings than will fit in the Reading Frame.
  • Another quirk is that the Up-arrow and Down-arrow keys generally do not affect what is displayed in the Reading Frame (even though they may move the text cursor within the document) unless they affect which part of the document is under the cursor. This is unlike other programs such as word processors. You need to get used to using only the mouse cursor to navigate within a page.
  • Some computer vendors use certain of LowBrowse's keystroke combinations for other purposes. For example, some HP computers use Ctrl + Alt + S to bring up an HP support application. These conflicting keystroke combinations can usually be re-configured or turned off.


Design Philosophy

LowBrowse is free, open source software, offered without charge. People with good vision don't have to pay for browsers. Why should those with poor vision?

LowBrowse does quite a lot, but with very few commands, so users have to remember very little. All of the basic commands are accessible by a an accelerator key (here called Accel, it is the Control key for Windows and Linux and the Command key for Mac) + Alt + <some letter> key combination, except for image zoom, which is accessed by Ctrl + mouse wiggle. Accel + Alt + H opens a tab with Quick Help for all of these. The only other keystrokes to remember are the arrow keys (left and right to go forward or backward in text; up and down to increase or decrease image size), and the + (plus) and - (minus) keys, which can be pressed either with or without the Shift key.

Credits, Acknowledgements and Dedication

LowBrowse was originally developed in the Arlene R. Gordon Research Institute at Lighthouse International by vision scientist Aries Arditi, Ph.D. under a research grant from the National Eye Institute. Some code from an earlier version of LowBrowse was contributed by Jianwei Lu, Ph.D. Its design was inspired by, and guided by vision research results collected and contributed by vision scientists too numerous to recount here, over the past 25 years. The code for the speech access library was mostly written by Charles L. Chen, of CLCWorld.net. Charles has authored other fine extensions for Firefox, most notably the accessibility extension FireVox.

LowBrowse owes a great deal also to the many contributers to the Mozilla platform who designed XUL and made it possible to extend the browser's interface in such a elegant and effective way.

This software is dedicated to Eleanor E. Faye, M.D., whose pioneering work at Lighthouse International since 1954 has been instrumental in sparking worldwide interest in low vision, and which attracted the interest of the National Eye Institute, which has been a primary advocate and funder of low vision research.

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