Resolution The core of 1080i is its resolution. The resolution is 1920x1080 pixels. This means that each
video frame has 1,920 pixels horizontally and 1,080 pixels vertically. This results in over two million individual pixels per frame. This high resolution is why 1080i is called "high-definition". It offers a significant improvement over standard-definition formats, which typically have much lower pixel counts. The 1920x1080 resolution allows for greater detail and clarity in images. This makes it ideal for larger screens where higher pixel density is essential to maintain image quality. The increased resolution is particularly noticeable in fine details such as textures, text, and intricate patterns. These can be rendered with much greater accuracy than in lower-resolution formats.
Interlacing The "i" in 1080i stands for interlaced. This refers to how each video frame is displayed. Instead of showing the entire frame at once, the interlacing technique divides each frame into two separate fields. The first field contains all the odd-numbered lines (1, 3, 5, etc.), and the second field contains all the even-numbered lines (2, 4, 6, etc.). These two fields are displayed one after the other. The odd lines are shown first, followed by the even lines. This happens very quickly, around 50 or 60 fields per second. The human eye sees these two fields as a single, continuous image. The main advantage of interlacing is that it allows for a higher frame rate without needing more bandwidth. This results in smoother motion, especially for content with moderate to fast movement, like sports broadcasts. However, interlacing also has some drawbacks. Since the two fields are captured at slightly different times, fast-moving objects can appear misaligned between the two fields. This creates a visual artifact called "combing." This can reduce image quality, especially in scenes with a lot of motion. Modern display devices often use deinterlacing algorithms to combine the two fields into a single progressive image before displaying it.
Frame rate The
frame rate of 1080i is usually 50 or 60 Hz. It depends on the region. In areas using the
PAL or
SECAM standards, like Europe and parts of Asia, the frame rate is 50 Hz. In regions using
NTSC, like North America and Japan, the frame rate is 60 Hz. The frame rate refers to how often a new field is shown per second. At 50 Hz, 50 fields are shown each second. This results in 25 full frames per second when the odd and even fields are combined. At 60 Hz, 59.94 fields are shown per second. This results in 29.97 full frames per second. Interlacing affects how motion is perceived in 1080i. Since each field represents a slightly different moment in time, motion can appear smoother compared to lower frame rate progressive scans. However, this also means 1080i can struggle with fast-moving scenes. The interlaced fields might not perfectly align, leading to motion artifacts. The
European Broadcasting Union (EBU) prefers to use the resolution and
frame rate (not field rate) separated by a
slash, as in
1080i/29.97 and
1080i/25, likewise 480i/29.97 and 576i/25. Resolutions of 1080i59.94 or 1080i50 often refers to 1080i/29.97 or 1080i/25 in EBU notation.
Signal transmission The 1080i video signals can be carried by four main digital television broadcast systems:
ATSC,
DVB,
ISDB and
DTMB. In both ATSC and DVB systems, the 1080i signal is compressed using codecs like
MPEG-2 or
H.264 to reduce the bandwidth required for transmission. In the United States, 1080i is the preferred format for most broadcasters, with
Warner Bros. Discovery,
Paramount Global, and
Comcast owned networks broadcasting in the format, along with most smaller broadcasters. Only
Fox- and
Disney-owned television networks, along with
MLB Network and a few other cable networks, use
720p as the preferred format for their networks;
A&E Networks channels converted from 720p to 1080i sometime in 2013 due to acquired networks already transmitting in the 1080i format. Many ABC affiliates owned by
Hearst Television and former
Belo Corporation stations owned by
Tegna, along with some individual affiliates of those three networks, air their signals in 1080i and upscale network programming for master control and transmission purposes, as most syndicated programming and advertising is produced and distributed in 1080i/p, removing a downscaling step to 720p. This also allows local newscasts on these ABC affiliates to be produced in the higher resolution (especially for
weather forecasting presentation purposes for map clarity) to match the picture quality of their 1080i competitors. == PAL speed-up ==
Motion pictures shot on film to fit a 16:9 widescreen format (1.78:1) are typically intended to be played back at 24 frames per second. When
telecined and played back at the PAL standard 25 frames per second, films run 4.1% faster than the original, and 4.2708% faster than the NTSC film standard 23. frames per second.
High-definition television (HDTV) broadcast standards utilize 1080i (interlaced) or 720p (progressive) formats, typically offering 1920x1080 resolution. Key, region-specific formats include 1080i25 for PAL (50 fields/second), 1080i30 for NTSC (60 fields/second), and 1080i24 for film, often converted via telecine for 25/30 frames per second, 1080i50/60 broadcasts. PAL speed-up does not occur on footage intended for playback at 25 frames per second. == See also ==