Video resolution

The video resolution includes the same parameters as the image resolution (rows and columns or number of pixels , aspect ratio ) and extends them to include the temporal aspect of the frame rate .

The frame rate is given in Hertz . A distinction must be made between the repetition of partial (fields) and full images (frames, progressive (scan)) . The former is done mostly with fields in interlaced (interlaced) .

A resolution that corresponds exactly to the physical resolution (number of pixels) of a display device is called native resolution .

terminology

Often in the digital sector, “ PAL ” is used as an abbreviation for “625 lines / 25 image changes per second with PAL color carrier” and “ NTSC ” as an abbreviation for “525 lines / 30 image changes per second with NTSC color carrier”. This is wrong, however, because component signals are used almost exclusively in digital technology. PAL, SECAM and NTSC are by definition ( television standard ) procedures for color transmission in analog television .

In order to differentiate between different video resolutions, a short form has become established, especially in the television sector: The number of visible lines is followed by a letter - which indicates full-screen (p) or interlaced (i) - and the frame or field frequency; on the other hand, if the frequency is omitted, it is only an indication of the image resolution. The aspect ratio (display and transmission) and other parameters, such as the number of lines actually transmitted or dots per line, are not specified in these abbreviations. There are variants that always specify the frame frequency and / or separate the frequency with a slash (/).

Image resolutions of videos in scale comparison

576i50 is a typical SDTV resolution. In the HDTV range are 720p and 1080i usual. Of Full HD speaking from 1080p23,976.

Adjustments to the image resolution

When using different video formats, it is often necessary to adjust the image resolution to ensure compatibility. In analog television broadcasting in particular, there are often rectangular instead of square pixels. For example, CIF was developed in order to be able to display NTSC and PAL signals during video conferences without distortion. The images are stretched horizontally by over 8% (352 to 384 points, see anamorphic ). But also HDTV is often compressed by 25% in practice (see HDCAM ), sometimes by 50% (see HDV ). PAL images are often 6.25–30% compressed. Higher compression is also possible in digital television and can often be found on various channels of the pay TV broadcaster Sky Deutschland .

Resolving power of the film

The 35 mm film format is currently (as of 2009) the most important for high-quality productions and is considered the standard format for cinema projections. The resolving power of films depends on the graininess of the film material used and describes the ability to reproduce fine details in the photo emulsion . Film scanners are used to convert the film image into digital video material. Since the scanning process also affects the video resolution, the film should be at least 4K , i.e. 4,096 pixels in the horizontal plane. At 4K resolution , a 35 mm film image of the maximum size (full aperture, 24.576 mm × 18.67 mm) results in a number of 3112 vertical pixels (12.7 MP). 35 mm films are mostly processed in digital systems in a resolution of 2K, corresponding to 3.19 million pixels or 2.21 million pixels, beginning with the introduction of CIF 709 and increasingly in 1920 × 1080 instead of 2K.

4K exposure is extremely rare so far; also because 4K scanners / DI / imagers have only recently become available again as series devices after Kodak withdrew the cineon system from the market in the mid-1990s due to lack of demand. The higher-quality 65 mm / 70 mm film has now become a niche because it has not been able to establish itself despite its better quality. In addition to the IMAX , where it is scanned in and exposed for digital post-processing with up to 8000 × 6000 pixels, it is only used in commercial film production in exceptional situations and formats.