definition is 625 lines. (The former is known as NTSC; the latter is PAL).
High Definition (HD)
Although much hype has been made about HD, the concept itself is simple to understand. Technically, anything that breaks the PAL barrier of 625 lines can be called high definition. The most common HD formats feature 720 and 1080 scan lines.
Ultra High Definition
Ultra high definition features an amazing 4,520 lines of horizontal resolution. Known as “4k” technology because the scan lines exceed 4,000, it will no doubt be the future industry standard.
The following photos show the relative size of the different formats. The first one represents the typical digital video frame (DV and DVCAM). Notice how detail improves as the number of scan lines increases. The final photo illustrates the huge leap in image detail 4k technology provides.
As a point of reference, the typical flat computer monitor has 2,000 lines of resolution. 35mm film–as perceived by the human eye–falls in the mid HD range. For more on 35mm comparisons please see our sample lesson: HD vs. 35mm.
4k technology is based on the proprietary 12 megapixel chip developed by the Red Digital Cinema Company. Their affordable Red One camera can shoot at all popular scan rates, including those shown above. 4k technology may prove to be the death knell for 35mm film.
Comparison
There are two factors that can be compared: colour and resolution. Most casual observers will agree that, assuming a quality TV monitor, HD colour is truly superb. To avoid a longwinded mathematical argument, let’s accept this at face value and focus on comparing resolution, which is the real spoiler.