Screen PPI, the resolution in the end how much needs to meet?
Recently I wanted to buy a 43-inch TV, 720P and 1080P 500 Ocean worse. I can not help tangled up. Look online fierce arguments, some people say not as good as 1080 clear, some people say that the naked eye can not see the difference. I can not decide. It seems that many people are not enough to understand this.
No way, only in-depth look at the. The following report.
First described the resolution and PPI. Resolution is the amount (a few screen pixels), PPI is the density (number of pixels per unit). In fact, just come up with these two values, it is unable to answer our questions today. Since different screen sizes on the same resolution, PPI different density, if the density is too low, there will be a feeling dot (pixel think villain battle NES). The same PPI, as will different visual distances, resulting in different lattice flu.
Resolution algorithm
PPI meaning
1. The first to explain why the smaller the distance, the more stuff. Since the height of the same object, the greater the distance, the smaller the angle of view angle (shown α). Once α small to a certain value, because of the loss of visual field angle is too small (sight).
The structure of the retina and the lens curvature capacity, as currently defined, a visual healthy person, probably in an angle of vision min (1 ° = 60 ') (of course, few people can break this limit, and the people's relatively poor eyesight, then this value is very conservative)
References: minimum resolution of the human eye perspective
perspective 1 '
angle and distance
2. 720P and 1080P so there is no difference in the end?
If at a certain distance, on the resolution of 720P screen naked eye can not detect a matrix of pixels, the screen 720P and 1080,2K, 4K are no different.
Assuming a common cell phone screen is the 1080P, the size of 5 inches.
Resolution = 1920 * 1080
Size = 5 "
Calculating PPI = [√ (1080² + 1920²)] / 5 = 440, meaning 440 pixels / 1 inch, which means that every two pixel distance of 1/17 mm,
To give 0.79 'if the human eye to see a screen of 25 cm, two adjacent pixels angle α = 2 · arctan (1/17/2) / 250 = 2.9 * 10 ^ -4 rad, turn angle
Comparative 1 ', the indexing is very small, in fact, it is sufficient. When you use this phone, it is the feel of the pixels on the screen.
3. Next, we take a look at. 43 inches TV, 720P resolution, in the range of 2 meters, will be affected by the quality of the pixel matrix.
Dimensions 43 "
Resolution: 1280 * 720
By math, PPI obtained: 45.5, which means that two adjacent pixels distance of 0.55mm.
After math, 0.997 Angle α is the angle indexing. 1 contrast 'indexing, you can see this value, it is still very small, most people are unable to tell the difference therein.
According to this algorithm, can be calculated from the current size by watching television screen in much the resolution to meet people's needs.
End.
references:
Time to prepare: 20,180,101