Anais do IHC'2001 - Departamento de Informática e Estatística - UFSC

Anais do IHC’2001 - IV Workshop sobre Fatores Humanos em Sistemas Computacionais 299
c) to set parameters for the computational part at two different moments in the
computation: to start the method (initialisation) or to provide information that is
used to dynamically reconfigure parameter values (steering);
d) to compose the object delineation from "primitive" results selected among a
number of possible delineations generated automatically by the computational part;
and
e) to build a dedicated computational method, choosing the appropriate low-level
image processing operations and the corresponding parameters.
These aspects are complementary and found in combination in interactive
segmentation methods found in the literature.
4. Discussion
Each aspect presented above has different implications to the ISM’s potential usability,
determining the accuracy and precision of the result to be achieved and the expected
operation efficiency. When designing and evaluating a new interactive method for image
segmentation, it is important to carefully choose a combination of concepts, criteria and
strategies that can help to improve not only its efficiency, but also its usability.
With respect to the type of data input, we should investigate which are the most
adequate interaction styles and widgets for each situation concerning particular set of tasks
and users. These are typical problems in HCI: interaction style selection – see
Shneiderman (1998), Newman and Lamming (1995) - and interaction object selection –
see Bodart and Vanderdonckt (1994). The consequence of user input is directly related to
low-level dialog design. Sequencing and availability of user actions (user interface syntax)
have a large impact on the interaction simplicity – see Newman and Lamming (1995).
Likewise, the computational component behavior can be made “intelligent” by anticipating
actions or replacing user interventions for interaction efficiency. Finally, the user role in the
process is related to high-level dialog design. It indicates the decision level and the degree of
freedom the user has with respect to the segmentation goals, determining how much and
when the user can interfere in the segmentation process. The examples above represent a
limited excursion into a territory that includes many other possible perspectives such as
recently explored by Randell and Johnson (2001).
References
Bodart, F. and Vanderdonckt, J. (1994) “On the Problem of Selecting Interaction Objects”.
In: Proc. BCS HCI'94, August 1994, Cambridge Univ. Press. p. 163-178.
Gonzalez, R.C. and Woods (1993) R.E. “Image Segmentation”. In: __. Digital Image
Processing. Addison-Wesley. p.413-481.
Newman, W.M. and Lamming, M.G. (1995) Interactive Systems Design. Addison-Wesley.
Olabarriaga, S. and Smeulders, A.W.M. (2001) “Interaction in the Segmentation of
Medical Images: a Survey”. Medical Image Analysis, v.5. p.127-142.
Randell, R. and Johnson, C. (2001) “A Comparison of Methods for Analysing Human-
Computer Interaction Failure in the Medical Domain”. Tech. Report. Univ. of Glasgow.
http://www.dcs.gla.ac.uk/~rebecca/comparison.pdf
Shneiderman, B. (1998) Designing the User Interface, Addison-Wesley.