What is HDTV ?

HDTV  or  High-definition television is video that has resolution substantially higher than that of traditional television systems (standard-definition TV, or SDTV, or SD). HDTV has one or two million pixels per frame, roughly five times that of SD. Early HDTV broadcasting used analog techniques, but today HDTV is digitally broadcast using video compression.

High-definition display resolutions

Video format supported [image resolution]	Native resolution [inherent resolution] (W×H)	Pixels		Aspect ratio (W:H)		Description
		Actual	Advertised (Mpixel)	Image	Pixel
720p 1280×720	1024×768 XGA	786,432	0.8	4:3	4:3	Typically a PC resolution (XGA); also a native resolution on many entry-level plasma displays with non-square pixels.
	1280×720	921,600	0.9	16:9	1:1	Standard HDTV resolution and a typical PC resolution (WXGA), frequently used by high-end video projectors; also used for 750-line video, as defined in SMPTE 296M, ATSC A/53, ITU-R BT.1543.
	1366×768 WXGA	1,049,088	1.0	683:384 (approx. 16:9)	1:1	A typical PC resolution (WXGA); also used by many HD ready TV displays based on LCD technology.
1080p/1080i 1920×1080	1920×1080	2,073,600	2.1	16:9	1:1	Standard HDTV resolution, used by Full HD and HD ready 1080p TV displays such as high-end LCD, Plasma and rear projection TVs, and a typical PC resolution (lower than WUXGA); also used for 1125-line video, as defined in SMPTE 274M, ATSC A/53, ITU-R BT.709;

Video format supported	Screen resolution (W×H)	Pixels		Aspect ratio (W:H)		Description
		Actual	Advertised (Mpixel)	Image	Pixel
720p 1780×956	1780×956 Clean Aperture	876,096	0.9	16:9	1:1	Used for 750-line video with faster artifact/overscan compensation, as defined in SMPTE 296M.
1080p 1920×1080	1888×1062 Clean aperture	2,005,056	2.0	16:9	1:1	Used for 1125-line video with faster artifact/overscan compensation, as defined in SMPTE 274M.
1080i 1920×1080	1440×1080 HDCAM/HDV	1,555,200	1.6	16:9	4:3	Used for anamorphic 1125-line video in the HDCAM and HDV formats introduced by Sony and defined (also as a luminance subsampling matrix) in SMPTE D11.