Samsung Galaxy NX500 Camera User Manual (en)

Shooting Functions > 
The Center-weighted mode calculates a broader area than the Spot mode 
does. It sums up the amount of light in the center portion of the shot 
(60–80 %) and that of the rest of the shot (20–40 %). It is recommended 
for situations where there is a slight difference in brightness between a 
subject and its background or where the area around a subject is large 
compared to the overall composition of the photo.
The Spot mode calculates the amount of light in the center. When you 
capture a photo in conditions where there is a strong backlight behind a 
subject, the camera adjusts the exposure to shoot the subject correctly. For 
example, when you select the Multi mode in a strong backlight condition, 
the camera calculates that the overall amount of light is abundant, which 
results in a darker photo. The Spot mode can prevent this situation as it 
calculates the amount of light in a designated area.
As the photo illustrates, the subject is in a bright area while the 
background is dark. The Spot mode is recommended for a situation like 
this where there is a large difference in the exposure values between the 
subject and the background.