G+_Duncan Jaffrey Posted January 19, 2015 Share Posted January 19, 2015 I keep struggling to understand the display definition terms HD, FHD QHD, qHD, WQHD, 4k UDH, UHD-1 I keep researching it loosely and then forgetting the subtle differences, Well I finally have come to a point where I think I understand it and won't forget it. Important things to know * Not all Q's stand for the same thing. * After FHD the measurement in K's was switched from the vertical to the longer horizontal measurement (bastard confusing move) * This doesn't even discuss the difference between and transition from rectangle to square pixels. Aspect ratios, screen resolutions, pixel count and pixels per inch/ density. Aspect rations, the easy bit The first thing to know about screens have a vertical and a horizontal measurement, and they have different proportions. The old screens were typical almost as high as they were wide, they mainly conformed to a 4:3 ratio or for ever 4 units of length it was 3 units tall. eg a screen 4" wide would have been 3" tall or a screen 20 cm wide would have been 15 cm tall. For the old school amongst us VGA and SVGA screens were 4:3. The 16:9 ratio became very popular with Monitors and TV's alike and would account for the majority of the screens today. For these displays for every 16 units of length it is wide the display is 9 units of length high. Screen resolutions. This is what all the letters and numbers are about, or is it. Early in the PC days we have the VGA display. (it had a 4:3 aspect ratio). is was 640 pixels wide by 480 pixels high. This measurement of 640 x 480 is the screen resolution. The story of k's Jump to a few years ago when HD came out. HD or high definition ( a relative term to the day) was 1280 pixels wide by 720 pixels high (16:9 aspect ratio), it was also known as 720(p or i). This saw 2 terms for the same display, HD is 720 and 720 is HD (except where some people use HD to describe FHD). Then we quickly got FHD (still 16:9) also known as 1080 (again p or i) this screen was 1080 pixels high by 1920 pixels wide. This was technically the beginning of the "K" TVs. It was a 1k display measured by its width of 1080 pixels. Although the term 1k was never really used. Now it gets a little messy. Then we got 2k. So that's easy if the "1k" was 1080 by 1920 then a screen that was 2000 pixels high would be about 3555 pixels wide, right. WRONG. At this point the measurement of K switched from the shorter vertical measurement to the longer horizontal measurement. So a 2k standard display at 16:9 ratio that was 2560 pixels wide is 1440 high. This is known as WQHD or Wide Quad High Definition or 1440(rarely). Pixel count and the issues with Q q. So now we have a 2k 16:9 display with Quad in its name. Quad is not "4K" in this instance the Quad is measuring the pixel count. going back over our old sizes VGA =640 * 480 = 307'200 pixels HD =720 * 1280 = 921,600 pixels FHD =1080 * 1920 = 2'073'600 WQHD =2560 * 1440 = 3'686'400 The Q in WQHD (also know as QHD which in turn gets confused with qHD) stands for Quad, well quad what you ask, it is 4 time the pixel count on a "HD or 720" display. HD = 921,600 pixels and WQHD is about 4 time larger at 3'686400 pixels. So that's why Quad isn't 4K. Now then a qHD display must be the same thing right? 2560 * 1440. WRONG. The little q (which I have seen accidentally printed as a capitol Q, many, many times) stands for quarter, so qHD = quarter High Definition or a Quarter of FHD at 1080 * 1920 = 2'073'600 (nice how the big Q and little q reference off 2 different display standards), qHD being 960 * 540 = 518'400. So shouldn't this be qFHD?? apparently no because some standards use HD and FHD interchangeably it seems, convenient. 4K, where we're headed? You will be please to know that the K is measure pixel length again, in fact its kept with the 2k trend and its measuring the longer pixel length of width of a 16:9 screen. So a 4K TV screen must be at least 4000 pixels right? WRONG again. the 4K TV, UHD, Ultra High Definition standard display is 3840 pixels wide by 2160 pixels high. 3840 * 2160 = 8'294'400 pixels. Will we let them off the being 160 pixels short of 4000, right? They define it as "being in the order of 4000 pixels. Can I pay my $4000 bills in the order of $4000 with only $3840? Lets not forgot that between "1K" and 2K they switched to measuring the longer of the 2 axis, so a 4K display is not 4 times as long in pixels as a 1K FHD display was, it is however 4 x as many pixels in pixel count. So now the K is not measuring the pixel length anymore, now we're comparing pixel count? You hear it both ways. The actually "4K" display standard is a 17:9 aspect ratio display measuring 4096 * 2160 pixels so it is measuring pixel length, for interests sake the 8K standard also measures pixel length coming in at 8192 * 5120 at the 16:10 aspect ration. (why the keep switching aspect rations is beyond me) Pixels per inch. This is actually the easiest and most consistent of the terms. The PPI is simply the pixel length contained along an inch of the display (for square pixels this is the same on either axis). That's why you get more PPI on a 5" 1080 FHD display as compared to a 46" 1080 FHD display. The end. In short, it's all bat shit crazy.? Link to comment Share on other sites More sharing options...
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