Camera Canvas: Image Editing Software for People with Disabilities
Christopher Kwan and Margrit Betke
{ ckwan, betke } @ cs.bu.edu
http://cs-people.bu.edu/ckwan/cameracanvas
Image and Video Computing Group
Department of Computer Science
Boston University
Abstract
Techniques
We developed Camera Canvas, photo editing and picture drawing
software for individuals who cannot use their hands to operate a
computer mouse. Camera Canvas is designed for use with camerabased mouse-replacement interfaces that allow a user with severe
motion impairments to control the mouse pointer by moving his or
her head in front of a web camera. To make Camera Canvas accessible
to as wide of a range of movement abilities as possible, we designed
its user interface so that it can be extensively tailored to meet
individual user needs. We conducted studies with users without
disabilities, who used Camera Canvas with the mouse-replacement
input system Camera Mouse. The studies showed that Camera
Canvas is easy to understand and use, even for participants without
prior experience with the Camera Mouse. An experiment with a
participant with severe cerebral palsy and quadriplegia showed that
he was able to use some but not all of the functionality of Camera
Canvas. Ongoing work includes conducting additional user studies
and improving the software based on feedback.
Experiments and Results
Ongoing Work
 Conducting user studies with people with disabilities.
 Users without disabilities:
 Recent studies with 28 users without disabilities.
 Investigating using simple games to detect optimal interface settings
 Software found to be easy to understand and use, even without
for each user (Fig. O1, O2).
prior experience with the Camera Mouse input system.
 Generalizing UI techniques into a tool for making existing software
more accessible [4] (Fig. O3).
 Download and try Camera Canvas:
 http://cs-people.bu.edu/ckwan/cameracanvas
 More information about our research:
 http://cameramouse.bu.edu
Figure T1: Using the Selection tool in Camera Canvas. The Sliding Toolbar has a
Horizontal-Top layout with larger buttons.
Figure E1: Drawings created by users without disabilities.
 User with severe cerebral palsy and quadriplegia:
 Sliding Toolbar: good concept but many accidental clicks.
 User may benefit from fewer buttons on toolbar or more
Motivation
hierarchical approach.
 Give people with severe motion impairments, who cannot use their
 Difficult for user to keep cursor on top of buttons.
hands to operate a computer mouse, an additional outlet for
 Ability to configure UI settings was key.
communication and expression.
 Design for use with Camera Mouse [1]: software that uses a web
Figure T2: Using the Floating
Selection Box to pick a portion of
an image.
Figure T3: Adjusting the
rotation of an image using a
Preview Choice Box.
 User had success in using Move and Zoom features, which involved
Figure O1: “Catch the Butterfly” game.
Recommends which axis and area of the screen
are best for the user by having her follow a
butterfly. Green lines show ideal mouse
trajectory, red circles show actual trajectory.
Figure O2: “Pop the Balloon”
game. Recommends button
size for user by having her try
to keep the mouse cursor still
within a small area. The
balloon is the ideal area, red
circles show the actual mouse
movement area.
boundary crossings rather than clicks.
camera to track a feature on a user’s face so he can control the mouse
 Changes are needed, but major improvement over testing initial
pointer by moving his head.
version with user.
 Gain general knowledge and techniques to apply to future projects
for people with disabilities.
Figure O3: The Menu Controller [4] accessibility tool re-displaying a
menu of Windows Media Player in a more accessible layout.
Figure M1: A Camera Mouse user
interacting with the computer.
Figure M2: The Camera
Mouse software tracking a
user’s nose.
Challenges
Figure T4: Drawing a picture in Camera Canvas. The Sliding Toolbar has a Vertical-Right
layout with smaller buttons.
 Helper Box Drawing:
 Addresses “Midas touch” problem.
 Alternative to click-and-drag (not possible with Camera Mouse).
Figure E2: An image edited by
a user with severe cerebral
palsy. He was able to rotate
the image (presented to him
upside-down) and experiment
with drawing several shapes
on the image .
Figure E3: A user with severe cerebral palsy
interacting with Camera Canvas using the
Camera Mouse.
Acknowledgements
We would like to thank the participants of our user studies for their
 Making complex image editing tasks possible with Camera Mouse.
valuable feedback. We would also like to thank Mikhail Breslav, Samuel
 “Midas touch”: accidentally clicking when you just want to look.
Epstein, Nathan Fuller, John J. Magee, Eric Missimer, Isaac Paquette,
Iterative Development
 Designing for a wide range of movement abilities:
 Features continually designed, implemented, tested with users, and then refined
 Better control along a certain axes.
or redesigned based on feedback.
 Good control only in a certain range or areas.
 Can only click buttons of a certain size.
Ashwin Thangali, Diane Theriault, Gordon Towne and Zheng Wu for
their support throughout the development of this program and their
assistance during user studies. We gratefully acknowledge funding from
the National Science Foundation (HCC grants IIS-0910908, IIS-0713229,
 Software remaining usable when abilities degrade over time.
and IIS-0855065) and from the Boston University Undergraduate
Research Opportunities Program.
Techniques
References
Figure T5: The Helper Box Drawing process.
 Sliding Toolbar (Fig. T1, T4):
 Constrains movement along one axis.
Configuration
 If user cannot reach buttons, he can slide them to the center of
the screen.
 Toolbar Orientation: Horizontal or Vertical, depending in which axis user has
 Sliding allows toolbar to contain more buttons than can fit on
better control.
screen.
 Toolbar Placement: Top, Bottom, Left, or Right depending on which area is most
Floating Selection Box (Fig. T2):
 Centralizes motion: user can adjust location, shape and size of
reachable for user.
 Button Size:
selection by placing the mouse cursor in static arrows.
 Smaller: allows more buttons to fit on screen, greater utility.
 Alternative to click-and-drag.
 Larger: makes it easier for user to click on the buttons, greater usability.
 Preview Choice Box (Fig. T3):
Toolbar Sliding Speed:
 High degree of control without need for great precision.
 Faster: allows user to reach desired button faster, greater utility.
 Preview provides feedback and allows experimentation.
 Slower: gives user more time to make decision, greater usability.
Figure I1: The evolution of drawing a purple circle across iterations.
1. M. Betke, J. Gips, and P. Fleming, "The Camera Mouse: visual
tracking of body features to provide computer access for people
with severe disabilities." IEEE Transactions on Neural Systems
and Rehabilitation Engineering, 10:1, pp. 1-10, March 2002.
2. M. Betke. "Intelligent interfaces to empower people with
disabilities," in Handbook of Ambient Intelligence and Smart
Environments. H. Nakashima, J. C. Augusto, and H. Aghajan
(Editors), pp. 409-432, Springer Verlag. June 2009. ISBN:
0387938079.
3. C. Kwan and M. Betke. Camera Canvas: Image editing software
for people with disabilities. In Proceedings of the 14th
International Conference on Human Computer Interaction (HCII
2011), Orlando, Florida, July 2011. In press.
4. I. Paquette, C. Kwan, and M. Betke. Menu Controller: Making
Existing Software More Accessible for People with Motor
Impairments. Department of Computer Science Technical Report
BUCS-2011-009, Boston University. March 2011.