Producing an Image Flashcards
1
Q
DISCAS (2)
A
- performance standard used when determining image size, text height, farthest and closest viewer, as well as appropriate viewing angles
- a comprehensive method and systems-based solution for determining display image size that considers the human factors for visual acuity and the viewer’s position relative to the image
2
Q
DISCAS factors (5)
A
- image height
- image resolution
- size of image content
- closest and farthest viewing distances
- relative horizontal and vertical viewing locations
3
Q
Acuity
A
eye’s ability to discern fine details
4
Q
kinds of acuity (2)
A
- Resolution acuity
- Recognition acuity
5
Q
Resolution acuity (2)
A
- the ability to detect that there are two stimuli, rather than one, in the visual field
- It is measured in terms of the smallest angular separation between two stimuli that can still be seen as separate
6
Q
Recognition acuity (7)
A
- the ability to correctly identify a visual target, as in differentiating between a “G” and a “C.”
- Usually, but not always, it is measured in terms of the angular dimension of the smallest target that can be discriminated
- A clinical eye chart, where visual acuity testing performed using letters, as is done clinically, is a form of recognition acuity testing
- Recognition acuity can involve very complex perceptual processing and often cannot be simply related to resolution acuity
- Although detecting the difference between an “O” and a “C” may be identical to resolution acuity, differentiating between a circle and an octagon is a more complex task
- Furthermore, the polarity (bright on dark versus dark on bright) can affect the result
- For example, dark-on-bright discriminations are often more appropriately considered contrast detection tasks than visual acuity tasks
7
Q
Optotype (2)
A
- a character used to assess a person’s visual acuity. It looks like a block letter, and is drawn with specific and rigid geometric rules. Only 10 optotypes are used on the traditional Snellen eye chart: C, D, E, F, L, N, O, P, T, and Z.
- The perception of five out of six letters (or a similar ratio) is called the Snellen fraction
8
Q
limit of your individual eyes’ acuity
A
When you look at these line pairs and move farther away from them, at some point the pairs will appear gray and blur together
9
Q
Closest Viewer
A
too close can not take in the screen all at once or might have to tilt their head back uncomfortably
10
Q
Farthest Viewer
A
how far away one can sit from a display and still make out the requisite level of detail
11
Q
Element (2)
A
- a group of pixels conveying an item of information
- the smallest discrete unit that a viewer must be able to discern and comprehend
12
Q
Percentage Element Height (3)
A
- height of an element in relation to the overall Image Height
- The BDM percent element height factor represents the ratio of element height to screen height expressed as a percentage (e.g., 1% represents an element height of 1 unit relative to 100 units screen height).
- DISCAS provides a range of percentages; users of the standard should vary this percentage according to the content.
13
Q
ADM
A
Analytical Decision Making
14
Q
BDM
A
Basic Decision Making
15
Q
Analytical Decision Making (3)
A
- covers situations where the viewer must be fully engaged with minute detail present in the content and needs to be able to resolve every element of the displayed image
- support critical assessments, including but not limited to examination of medical imaging, fine arts, engineering or architectural drawings, electrical schematics, photographic image inspection, forensic evidence, or failure analysis
- viewers are concerned with the finest discernable details and at this level of critical viewability, discerning individual pixels rather than individual elements, becomes the necessary criteria
