In today's digital age, video has become an indispensable part of our lives. From short-form video platforms to high-definition movies, video quality directly impacts our viewing experience. However, for non-professionals, concepts like resolution, HD, Ultra HD, 2K, 4K, 8K, SD, bitrate, and frame rate can seem somewhat complex. This article explains these fundamental concepts in simple terms and provides practical examples for calculating video size and clarity, enabling readers to understand better and apply this knowledge.
I. Resolution: A Collection of Pixels
Resolution refers to the number of pixels contained within a specific area of a video frame. A pixel is the smallest unit composing an image, each possessing a specific color and brightness value. Resolution is typically expressed as “width × height,” such as 1920×1080. This indicates that the video has a resolution of 1920 pixels horizontally and 1080 pixels vertically.
The Society of Motion Picture and Television Engineers (SMPTE) has established a series of high-definition digital television format standards, including commonly used resolution specifications:
720P: Its effective display format is 1280×720, utilizing progressive scanning.
1080P: Its effective display format is 1920×1080, also employing progressive scanning.
1080i: Contrasting with 1080p, 1080i uses interlaced scanning, also at a resolution of 1920×1080. This format may offer higher frame rates during transmission but may result in slightly lower image quality compared to 1080p.
2K: Features a horizontal resolution of approximately 2000 pixels. The most standard 2K resolution is 2048×1024, while a common 2K resolution is 2560×1440 (16:9). (UHDTV1) 4K: UHDTV1 refers to the VHD Ultra High Definition system defined by the SMPTE ST 2036-1 standard, featuring a resolution of 3840×2160 (16:9). (UHDTV2)
8K: UHDTV2 is also a VHD ultra-high-definition system defined by the SMPTE ST 2036-1 standard, achieving a resolution of 7680×4320.
Although the UHDTV standard does not assign official names to its defined formats, the ITU commonly uses the terms “4K,” “4K UHD,” or “4K UHDTV” in public announcements and press releases to refer to the 3840 × 2160 system, and “8K” to refer to the 7680 × 4320 system.
