Overview

When the moving picture is displayed, each frame is flashed for a short time (nowadays, usually 1/24, 1/25 or 1/30 of a second) and then immediately replaced by the next one. Persistence of vision blends the frames together, producing the illusion of a moving image.

The frame is also sometimes used as a unit of time, so that a momentary event may be said to last six frames, the actual duration of which depends on the frame of the system, which varies according to the video or film standard in use . In North America and Japan, 30 frames per s 🙂 (fps) is the standard broadcast, with 24 frames / s now for high definition video shot to look like movie. In the rest of the world, 25 frames / s is standard.

In systems historically based on NTSC standards, for reasons originally related to the [[Chromilog NTSC TV systems, the exact frame rate is actually (3579545 / 227.5) / 525 = 29.97002616 fps. ^[a] This leads to many synchronization problems which are unknown outside the NTSC world, as well as drop-frame timecode .

In film projection, 24 fps is the norm, such as IMAX , Showscan and Iwerks 70 , where 30, 48 or even 60 frame / s have been used. Silent movies and 8 mm amateur movies used 16 or 18 frame / s.

Physical film frames

In a strip of movie film, individual frames are separated by frame lines . Normally, 24 frames are needed for one second of film. In ordinary filming, the frames are photographed automatically, one after the other, in a movie camera. In special effects or filming animation , the frames are often shot at one time.

The size of a film frame varies, DEPENDING on the still format film or the motion picture format film . In the smallest 8 mm amateur format for movie motion pictures, it is only about 4.8 by 3.5 mm, while an IMAX frame is as wide as 69.6 by 48.5 mm. The larger picture is in relation to the size of the projection screen , the sharper the image will appear.

The size of the movie frame of motion picture also depends on the location of the holes, the size of the holes, the shape of the holes. and the location and type of sound stripe.

The most common film format, 35mm , has a frame size of 36mm when used in a still moving film where the film moves horizontally, but the frame size exception of VistaVision and Technirama where the film moves horizontally). Using a 4-perf pulldown , there are exactly 16 frames in one foot of film, leading to film frames sometimes being counted in terms of ” feet and frames “. The maximum frame size is 18 by 24 mm, (silent / full aperture), but this is greatly reduced by the application of sound track (s). A system called KeyKode is often used to identify specific physical film frames in a production.

Video frames

Historically, video frames are represented as analogue waveforms in which varying voltages represent the intensity of light in an analog raster scan across the screen. Analog blanking at the same time in the same way that frames lines did in film. Reasons for historical, Most systems used an interlaced scanning system in the frame qui Typically consisted of two video fields sampled over two Slightly different periods of time. This one is usually not a good picture of the scene, unless the scene being shot completely.

With the prevalence of digital technology, the video frame is a rectangular raster of pixels , and the analog waveform is typically in the same color as the YCbCr, and the analog waveform is typically O devices.

Standards for the raster digital video frame include Rec. 601 for standard-definition television and Rec. 709 for high-definition television .

Video frames are usually identified using SMPTE time code .

Line and resolution

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 is known to the total resolution of the frame. The higher image is the original image. But higher resolution introduces technical problems and extra cost. So compromises should be achieved in both the design and the image quality.

Viewing distance

The key parameter is the 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 minimum required resolution and k is the proportionality constant qui depends on the size of the monitor;

{\ displaystyle r = k ^ {2} \ cdot {\ frac {1} {d ^ {2}}}}

Since the number of lines is proportional to the resolution per line, the above relation can also be written as

{\ displaystyle n = k \ cdot {\ frac {1} {d}}}

where n is the number of lines. That means that the required resolution is proportional to the height of the monitor and inversely proportional to the remote viewing.

Moving picture

In moving picture (TV) the number of frames scanned is known to the 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 ). To increase the sense of motion, it is very similar to two consecutive phases. In each phase only half of the lines are scanned; only the lines with odd numbers in the first phase and only the lines with even numbers in the second phase. Each scan is known as a field . So the field rate is two times the frame rate.

Example (System B)

The maximum video bandwidth is 5 MHz. ^[1] The maximum number of sine signals the system is theoretically capable of transmitting is given as follows:

The system is able to transmit 5,000,000 sine signals in a second. Since the frame rate is 25, the maximum number of signals per frame is 200 000. (Actually about 19% of each line is The most useful articles are about 260.)

Still frame

A still frame is a single static image taken from a film or video , which are kinetic (moving) images. Still frames are aussi called Expired freeze frame , quick video, preview or misleadingly thumbnail , keyframe , poster frame, ^[2] [3] gold screen shot / grab / capture / dump . Freeze frames are widely used on video platforms and in galleries, to show viewers at preview or a teaser. Many video platforms have a standard to display a frame from mid-time of the video. Some platforms offer the option to choose a different frame individually. ^[4][5]

Video and movie artists still use frames Sometimes dans le video / movie to accomplish achieve special effects , like freeze-frame shots or still motion . ^[6]

Investigations

For criminal investigations It has Become a frequent use to publish still frames from monitoring videos in order to Identify suspicious persons and to find more Witnesses. ^[7] Videos of the 9/11 have been discussed for different interpretations. ^[8] For medical diagnostics Magnetic resonance imaging videos. ^[9]

Fourth wall use

Some humor is based on the fourth aspect of the film itself, with some animation showing characters leaving the film or the film malfunctioning. This one is used often in movies as well. These hearkens back to some early cartoons, where they were aware that they were in a particular way that they could look at the credits and be aware of something that is not part of the story as presented. These jokes include:

• Split frames – Where the fourth wall is broken by two frames, the lower half of the previous frame and the upper portion of the next frame, showing at once, usually showing frame lines , with jokes Involving Them comprenant un character crossing the frame Itself.
• Film break – A famous form of the joke, where the movie is snapped or deliberately broken, with the fourth wall coming into play during this period when, rightfully, there should be nothing on screen.
• Gate hair – A famous form of joke where the animator intentionally places fake “gate hairs” within the frame, which one of the animated characters plucks and removes from the frame.
• Editorial marks – Where these marks which would be an editor would normally employ a “work print” to indicate the presence of a fade or a “wipe” to the SFX department are animated, and the film follows follows, or does not t, depending upon the intended effect.
• Cue Marks – Uncirculated and Uncirculated for the Purpose of a Technological Change. This could also be used for the famous “false ending” effect, employed even today in popular songs. For Inglourious Basterds , the cue marks for the reel changes of the Nation’s Pride pseudo-documentary employed exceptionally broad scribed circles with a large “X” scribed within it-marks which would never be used in actual editorial practice to be clearly visible to the projectionist, but not obvious to the audience).
• Exiting the frame – This joke, an extension of the split frames joke, with the characters of the frame, sometimes finding themselves falling out of the cartoon entirely.

See also

• Akinetopsia (motion blindness)
• Aspect ratio (image)
• Frame rate
• List of film formats
• Shot (filmmaking)
• Widescreen
• Freeze frame (disambiguation)
• Freeze frame television
• Grammar film
• Frame rate
• Frame grabber
• Key frame
• slow motion
• Thumbshot

Notes

References