Case Study: Expert Evaluations of Complex UIs - Cross-Cultural Human-Computer Interaction and User Experience Design - page 54

A filter can be used afterwards, applied as a part of retouching. More fundamentally,
time can be manipulated also through the “undo” function that steps back through the
history of actions.

Interaction phases.
On the level of interaction sentence, the interaction changes to reflect the constant
evaluation of results on the user's part. The interaction sentence is then modified
or repeated accordingly. Considering the example from the transcripts, the action is
modified after the system's feedback (when the system shows in the preview window
the proposed change), or the action was needed only once (when clicking the “OK”
button). The middle of the interaction game differs from the beginning and end because
a new window is shown keeping the user accordingly away from the picture he or she
opened.

GIMP steps
(0) Open the picture to adjust.
(1) Find the proper function in the menu bar or toolbox.

(a) The subtask involved was to look at the toolbox for a button resem-
bling the intended action. A button showing a change of perspective
was found.
(b) Alternatively look through the menu items (especially in what seemed
as most related: Image -

> Adjustments, Tools - > Transformation

tools, and Filters - > Distortion) for a relative command (it was found

under Tools - Perspective). (A four-button

floating window has opened, the pointer changed, and the image ac-
quired boxes on each corner.)

> Transformation tools - >

(2) Drag the boxed corner of the image in the direction that would compensate
the perspective. Repeat this for every corner, as necessary. (The live preview
shows the proposed transformation).
(3) Click “Transform” in the floating window “Perspective.” (The transforma-
tion is applied). (See Figures 4.16 and 4.8.)
(4) Select “Filters -

> >

Lens distortion” to make further needed
corrections. (A window with a live preview and six sliders appear.)
(5) Drag each of the sliders to set the needed parameter. See the proposed result
in the preview.
(6) Click “OK” to apply the filter.
(7) Save changes to the file.

Distortion -

HE analysis
Direct manipulation/See and point.
Although the perspective of the image could be changed by dragging the mouse,
making further needed changes to the image perspective was only possible through a
window containing a set of controllers. All the actions are only visible in the preview
window.