多选题
Cells in the parvo system can distinguish between two colors at any
relative brightness of the two. Cells in the color-blind magno system, on the
other hand, are analogous to a black-and-white photograph in the way they
function: they signal. information about the brightness of surfaces but not
about their colors. For any pair of colors there is a particular brightness
ratio at which two colors, for example red and green, will appear as the same
shade of gray in a
black-and-white photograph, {{U}}hence any
border between them will vanish.{{/U}} Similarly at some relative red-to-green
brightness level, the red and green will appear identical to the magno system.
The red and green are then called equiluminant. A border between two
equiluminant colors has color contrast but no luminance contrast
The author mentions a "black-and-white photograph" most probably in order
to explain
- A. how the parvo system distinguishes between different shapes and
colors.
- B. how the magno system uses luminosity to identify borders between
objects.
- C. the mechanism that makes the magno system color-blind.
- D. why the magno system is capable of perceiving moving images.
- E. the brightness ratio at which colors become indistinguishable to the
parvo system.