Numeric precision in Microsoft Excel: Difference between revisions
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'''Frame''' is electronically coded still image in [[video]] technology | |||
==Line and resolution== | |||
{{main|Video}} | |||
The frame is composed of picture elements just like a chess board. Each horizontal set of picture elements is known as a [[line (video)|line]]. The picture elements in a line are transmitted as [[sine wave|sine]] signals where a pair of dots, one dark and one light can be represented by a single sine. The product of the number of lines and the number of maximum sine signals per line is known as the total resolution of the frame. Higher the resolution the more faithful the displayed image to the original image. But higher resolution introduces technical problems and extra cost. So a compromise should be reached in system designs both for satisfactory image quality and affordable price. | |||
==Viewing distance== | |||
For computing the lowest resolution which still seems satisfactory to viewers, the key parameter is the viewing distance, i.e., distance between the eyes and the monitor. The total resolution is inversely proportional to the square of the distance. If '''d''' is the distance, '''r''' is the required minimum resolution and '''k''' is the proportionality constant which depends on the size of the monitor; | |||
:<math> r = k^2 \cdot \frac{1}{d^2}</math> | |||
Since the number of lines is approximately proportional to resolution per line, the above relation can also be written as | |||
:<math> n = k \cdot \frac{1}{d} </math> | |||
where '''n''' is the number of lines. That means that the required resolution is proportional the height of the monitor and inversely proportional to the viewing distance. | |||
==Moving picture== | |||
In moving picture (TV) the number of frames scanned per second is known as frame rate. The higher the frame rate, the better the sense of motion. But again, increasing the frame rate introduces technical difficulties. So the frame rate is fixed at 25 ([[CCIR System B|System B/G]]) or 29.97 ([[CCIR System M|System M]]). But for increasing the sense of motion it is customary to scan the very same frame in two consecutive phases. In each phase only half of the lines are scanned; only the lines with odd number in the first phase and only the lines with even number in the second phase. Each scan is known as a field. So field rate is two times the frame rate. | |||
==Example (system B)== | |||
{{Main|CCIR System B}} | |||
In system B the number of lines is 625 and the frame rate is 25. The maximum video bandwidth is 5 MHz. <ref> ''Reference Data for Radio Engineers'', ITT Howard W.Sams Co., New York, 1977, section 30 </ref> The maximum number of sine signals the system is theorically capable to transmit is given as follows: | |||
The system is capable to transmit 5 000 000 sine signals in a second. Since the frame rate is 25, the maximum number of sine signals per frame is 200 000. Dividing this number by the number of lines gives the maximum number of sine signals in a line which is 320. (Actually about 19% of each line is devoted to auxiliary services. So the number of maximum useful sine signals is about 260. ) | |||
==References== | |||
{{reflist}} | |||
{{Analogue TV transmitter topics}} | |||
[[Category:Television technology]] | |||
Revision as of 16:55, 16 November 2013
Frame is electronically coded still image in video technology
Line and resolution
Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. The frame is composed of picture elements just like a chess board. Each horizontal set of picture elements is known as a line. The picture elements in a line are transmitted as sine signals where a pair of dots, one dark and one light can be represented by a single sine. The product of the number of lines and the number of maximum sine signals per line is known as the total resolution of the frame. Higher the resolution the more faithful the displayed image to the original image. But higher resolution introduces technical problems and extra cost. So a compromise should be reached in system designs both for satisfactory image quality and affordable price.
Viewing distance
For computing the lowest resolution which still seems satisfactory to viewers, the key parameter is the viewing distance, i.e., distance between the eyes and the monitor. The total resolution is inversely proportional to the square of the distance. If d is the distance, r is the required minimum resolution and k is the proportionality constant which depends on the size of the monitor;
Since the number of lines is approximately proportional to resolution per line, the above relation can also be written as
where n is the number of lines. That means that the required resolution is proportional the height of the monitor and inversely proportional to the viewing distance.
Moving picture
In moving picture (TV) the number of frames scanned per second is known as frame rate. The higher the frame rate, the better the sense of motion. But again, increasing the frame rate introduces technical difficulties. So the frame rate is fixed at 25 (System B/G) or 29.97 (System M). But for increasing the sense of motion it is customary to scan the very same frame in two consecutive phases. In each phase only half of the lines are scanned; only the lines with odd number in the first phase and only the lines with even number in the second phase. Each scan is known as a field. So field rate is two times the frame rate.
Example (system B)
Mining Engineer (Excluding Oil ) Truman from Alma, loves to spend time knotting, largest property developers in singapore developers in singapore and stamp collecting. Recently had a family visit to Urnes Stave Church. In system B the number of lines is 625 and the frame rate is 25. The maximum video bandwidth is 5 MHz. [1] The maximum number of sine signals the system is theorically capable to transmit is given as follows:
The system is capable to transmit 5 000 000 sine signals in a second. Since the frame rate is 25, the maximum number of sine signals per frame is 200 000. Dividing this number by the number of lines gives the maximum number of sine signals in a line which is 320. (Actually about 19% of each line is devoted to auxiliary services. So the number of maximum useful sine signals is about 260. )
References
43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.
Template:Analogue TV transmitter topics
- ↑ Reference Data for Radio Engineers, ITT Howard W.Sams Co., New York, 1977, section 30