The current screen is split into 2 vertical sections of light and dark. There are 2 squares on this screen with 1 on each section. The square on the right lighter section should appear darker. However, if we turn off the left darker section, you will see both squares have the same intensity of light.
Furthermore, if we add different shades of grey squares to the sides of each square, the apparent difference in brightness is even more pronounced When a bright area lies next to a dark area, the brain tends to enhance the difference in brightness. Our brains read values of color based on their surrounding relationships.
There are a set of light and dark stripes on your screen. There appears to be a light area of grey on the left and a darker area of grey on the right. But just as on the previous screen, when the large bars are turned off one sees that the 2 inner areas of grey are the same shade.
A
B
The difference in light intensity between an image and its adjacent background is known as ‘contrast’. Contrast emphasizes the border between objects making the boundary between the two distinguishable. The phenomenon of seeing an object being drawn closer to its surroundings is known as ‘assimilation’. Assimilation is a perceived change in brightness or color in one part of an object in the direction of the brightness or color to another part or parts within the same picture. The brightness of the greys in these ambiguous exercises do not exist in nature objectively, but exist as a subjective experience within our brains. There is a solid sphere on this checkerboard pattern. There are 2 squares labeled, ‘A’ and ‘B’. The B square naturally appears lighter. However, if one moves the grey bar with the hand symbol over the 2 squares, they both appear as the same value.
