The eye... well, we've got two? But 3D stereo-movies are still pretty rare.
One eye:
Dynamic range (light to dark)
Normal contrast ratio is about 100:1 (about 6 1/2 stops)
Maximum contrast ratio is about 1,000,000:1 (about 20 stops)
Acuity (sharpness, resolution)
Maximum is about 0.73 millimeters at a distance of one meter.
Optimal sharpness is only in the center, where you're looking at.
Focus
Only one distance at a time is in optimal focus (sharp). Other distances are more or less blurred (unsharp). More light = smaller pupil => greater depth of field (less unsharpness, the zone of acceptable sharpness increases)
Rods and Cones
Rods and cones are both photosensitive, but respond differently to different frequencies of light. Rod cells are highly sensitive to light. However, they do not distinguish between colours, and have low visual acuity (a measure of detail). Cone cells, conversely, need high light intensities to respond and have high visual acuity. Different cone cells respond to different colours (wavelengths) of light.
The human eye is sensitive to red, green and blue light. If all three forms of cones are stimulated equally, then white is seen. If none are stimulated, black is seen. Most of the time however, the three forms are stimulated to different extents - resulting in different colours being seen.
| Cone type |
Name |
Range |
Peak sensitivity |
| Large |
R (Red) |
500 - 700 nm |
580 nm |
| Medium |
G (Green) |
450 - 630 nm |
544 nm |
| Small |
B (Blue) |
400 - 500 nm |
440 nm |
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How many colors can your monitor show, and how many colors can your eyes distinguish?
If you remove the ones you can not see, there's no visual loss of image quality.
This RGB (24 bits) gray spectrum on the left has all possible 256 gray tones in it.
Next are three gray spectrums, one with 128 tones, one with 64 tones, and one with only 32 tones. The 128 shows little loss, the 64 shows some loss, and the 32 is real bad.
But not all collors show the same loss at only 32 tones. Take a look at the following color gradients. I personaly can not see any loss in the yellow-to-white gradient.
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256 tones
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| 128 tones |
64 tones |
32 tones |
  
  
  
  
  
Guess how many different colors in this image:
(16x16 = 256 pixels)
answer: exactly 108
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