As we know that there are many different visual attributes, such as luminance contrast, orientation, spatial frequency, motion and so on, constitute any stimulus, from simple grating to complex object. But it seems that the visibility of a stimulus is dependent on luminance contrast when we detect a stmulus. Hence, the dependence may suggest that basic visual attributes could be classified into different classes.
Hi Qing,
If I understand you correctly, then I can say that it is possible as long as such classification produces meaningful differences when characterizing the observation.
HTH.
Samer
Hi Sarsam
so sorry to make you confused as my poor English. In a article , tha author wrtites 'Luminance and color are considered to be first order characteristics because they are sufficient to generate a contour. The other attributes as considered second order characteristics since they are constructed from spatial, temporal and interocular information, coded from color or luminance (Cavanagh, 1988).' So it seems that we can categorize visual attributes.
Qing
No worries Qing.
It's fairly possible to classify the attriubtes based on certain criteria (this what the authours did). However, general classification aspects depend on the idea behind the study and the stimuli though.
HTH.
Samer