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Contrast is a feature of visual stimuli that characterizes the difference in brightness between dark and light regions of an image. Perception of contrast is affected by the temporal frequency and spatial frequency properties of a stimulus, and the sensitivity to contrast in sine wave stimuli is characterized by the contrast sensitivity function.
A contrast effect is the enhancement or diminishment, relative to normal, of perception, cognition or related performance as a result of successive (immediately previous) or simultaneous exposure to a stimulus of lesser or greater value in the same dimension. (Here, normal perception, cognition or performance is that which would be obtained in ...
The Chubb illusion is similar to another visual illusion, the contrast effect.The contrast effect is an illusion in which the perceived brightness or luminance of an identical central visual target form on a larger uniform background varies to the test subject depending on the ratio of the central form's luminance to that of its background. [4]
Illusory palinopsia is often worse with high stimulus intensity and contrast ratio in a dark adapted state.Multiple types of illusory palinopsia often co-exist in a patient and occur with other diffuse, persistent illusory symptoms such as halos around objects, dysmetropsia (micropsia, macropsia, pelopsia, or teleopsia), Alice in Wonderland Syndrome, visual snow, and oscillopsia.
Hallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after using drugs, [1] including but not limited to psychedelics, dissociatives, entactogens, tetrahydrocannabinol (THC), and SSRIs.
The original version of the illusion involved a rapidly spinning black-and-white disk, painted in a way that would create the appearance of a gradient effect when in motion. [3] An equivalent static version of illusion is composed of a gray rectangle where the left half fades to a lighter shade as it approaches a vertical center line, and the ...
DAMP is diagnosed on the basis of concomitant attention deficit/hyperactivity disorder and developmental coordination disorder in children who do not have a severe learning disability or cerebral palsy. In clinically severe form, it affects about 1.5% of the general population of 7-year-old-children; 3-6% are affected by more moderate variants.
This contrast between the light and dark creates a sharper image. (Compare unsharp masking in digital processing). This mechanism also creates the Mach band visual effect. Visual lateral inhibition is the process in which photoreceptor cells aid the brain in perceiving contrast within an image.