1366x768 vs 1280x720

[therock003]

Why do they insist of manufacturing 1366x768 monitors when this means that 720p signal will have to upscale to match the Monitors native res? What's the point, and whey do they not produce 1280x720 instead?

[redwudz]

It's mostly related to the physical size of the LCD screen. They don't usually size the pixels for the different screen sizes, so a ~1920 X 1080 LCD screen will be about 23" on average.

[jagabo]

Even if the TV had a native 1280x720 resolution the image would be scaled because TVs usually overscan.

[edDV]

Why do they insist of manufacturing 1366x768 monitors when this means that 720p signal will have to upscale to match the Monitors native res? What's the point, and whey do they not produce 1280x720 instead?

The simple answer is the decisions to broadcast 704x480/576, 1280x720 and 1920x1080 predated LCD/plasma display technology. CRT TV displays actually scan 480/576, 720 or 1080 lines as interlace or progressive. The scanning system is essentially analog so digital input signals must go through a D/A process prior to scanning. A typical CRT HDTV is capable of interlace scan for 480/576/1080 (240/288/540 lines per field). Many also did progressive scan at 480p/576p for SD. 720p was the most difficult CRT display standard so was reserved for the highest models.

For ATSC/DVB digital television, 1920x1080 with 16:9 aspect ratio was chosen by psychological research. The goal was an ideal "home theater" experience for display of movies and dramatic TV series. 1280x720p/59.94 was chosen as an alternate high action sports/computer/game optimised format. The 720p resolution was backwards calculated from the 19Mb/s bit rate proposed for ATSC broadcast and from projections of progressive camera sensor technology. There was little consideration for digital display technology. Meanwhile, wide computer display resolutions were mostly driven by side by side document presentation requirements with little consideration or overlap with HDTV/2K cinema resolutions.

Digital HDTV displays receive a variety resolutions from analog and digital transmission sources, then progressively display at so called "native resolution". Ideal native resolutions could be and usually are different from transmitted resolutions. The HDTV's video processor scales* all input resolutions to native display resolution. 1920x1080 is the only TV resolution that matches optimized VESA LCD resolutions (although a vertically cropped version of 16:10 1920x1200 WUXGA).

A complicating factor for 1920x1080 HDTV displays is overscan. In normal mode you are not seeing pixel by pixel mapping. You are seeing the center ~95% of an upscaled image. Some HDTV sets have a unity scale mode (Samsung calls it "Just Scan"). Unity scale should be used for computer connections to get sharpest text display. Most HDTV VGA connections (PC port) are unity scale so you may find the VGA connection sharper on some TV's vs HDMI/DVI.
http://en.wikipedia.org/wiki/Overscan

1366x768 was chosen by mid size HDTV set makers because it maximized the number of addressable pixels they could put on an LCD or Plasma TV with commonly available memory and chip processors. Larger screens demand more pixels for the best perceived image. 1366x768 doesn't match any TV resolution so everything gets scaled. You also need to be aware that overscan is normal even for 1366x768 computer connections over HDMI/DVI. So, again you may find a sharper computer image over VGA. Native 1280x768 or vertically cropped 1280x720 16:9 screens are sometimes found on laptops or small computer displays.

As for 1280x720p upscaled quality on a 1366x768 display, it all depends on the quality of the HDTV video processor. Some models perform significantly better than others. Budget models usually use generic scaling/deinterlace/inverse telecine technology. The better TV makers use proprietary chips with advanced technology. Advanced technology usually carries patent royalty costs so expect the better performing HDTV sets to carry premium prices.


* HDTV video processors do more than scale the image. They also deinterlace, inverse telecine and image enhance for progressive display. 100/120/240 Hz HDTV sets repeat or process additional frames per second to smooth motion. Computer LCD monitors lack most of these features. Their scalers are usually poor so computer connections should be restricted to native display resolution and 60 Hz refresh.