1080i

1080i is an interlaced high-definition format with 1,080 valid vertical lines, typically denoted as 1920×1080. The letter `i` stands for "interlaced": a complete raster is divided into two fields—odd and even lines—which are captured or displayed at different times.

1080i50 indicates 50 fields per second, which typically results in 25 complete frame cycles per second; 1080i59.94 indicates approximately 59.94 fields per second. Writing the former as “50 frames” or simply referring to the latter as “30p” ignores the temporal sampling of interlaced fields. Moving objects can change position between two fields, so combing may occur when fields are merged. Deinterlacing requires distinguishing between stationary and moving areas, using methods such as field merging, interpolation, motion adaptation, or motion compensation to generate a progressive output. Simply discarding a field results in the loss of vertical detail, while direct interlacing produces artifacts in true interlaced motion. If the source was originally a progressive-scan film and was transmitted using interlaced frames or downconversion, correct restoration can recover the original frames.

Broadcast, HDV, and some Blu-ray programs use 1080i. It may be carried by MPEG-2, H.264, or other codecs, and may have different pixel widths and aspect ratios. The 1080i identifier does not indicate bit rate, master resolution, or deinterlacing quality.