Final answer:
Contrast ratio should be measured from multiple locations within the viewing area to accurately represent image quality and account for variations in luminance.
Step-by-step explanation:
The question addresses the topic of measuring contrast ratio, which typically relates to the way images are displayed and perceived in different viewing conditions. The contrast ratio should be measured from multiple locations within the viewing area to ensure accurate representation of image quality. This involves analyzing at least two contrasting fields, such as light and dark areas of an image, to determine the maximum and minimum luminance levels and calculate the ratio. Additionally, the concept of vision and how humans perceive visual stimuli, the distance objects fall on the retina, and how visual tests are conducted can assist in understanding why measuring from different locations is necessary for a comprehensive assessment.