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1440x1080 HD video via modern HD camcorders "explained" through pixel geometry. The question has been raised regarding how good 1440x1080 resolution from HD camcorders is when compared to "full" 1920x1080 resolution devices. While it is technically accurate to say that 1920x1080 images contain more pixels than 1440x1080 images the actual appearance to the native eye is not as different as logic might make you think. And the choice of "1440" as the resolution in the horizontal direction in a "1920x1080" world is not an arbitrary number but carefully selected due to pixel geometry considerations. Here's why. 1440x1080 video is recorded using rectangular pixels with an aspect ratio of 1.33:1 (the actual shape of the pixels, not the shape of the 1440x1080 image). Taking into consideration that most people like to try to understand screen ratios in terms of "square" (1:1) dots or pixels, this would mean that If you were to compare the 1440x1080 images with 1.33:1 rectangular pixels to 1920x1080 images with square (1:1) pixels then the two images so described would both end up with the same overall shape for the image - and that would be a 16:9 (or what we like to call a "1920x1080") shape. That's because when calculating the horizontal length for both situations 1.000 x 1920 = 1920 (of course) and 1.333333 x 1440 = 1920! Granted, a "true" HD 1920x1080 image contains more pixels in the horizontal direction but the fact of the matter is that in the vast majority of filming applications capturing 16:9 images with 1920 horizontally arranged "square" pixels is not perceptibly different than capturing 16.9 images with 1440 horizontally arranged "rectangular" pixels. A lot of this has to do with the fact that for most filming situations adjacent pixels contain a lot of the same or very similar video information. Add to this the possibility of interlacing or de-interlacing the final viewed product on a screen and the rectangular pixels might actually be better at displaying fast action with fewer visual artifacts, but that's another issue for another time. If one were filming highly intricate source material where there is a pixel to pixel difference due to source density (like, perhaps, microfiche or similar) then this would be a different story entirely. But the major application for most HD camcorders is movies, not high density data so one should not dismiss 1440x1080 "rectangular pixel-based" images in favor of 1920x1080 "square pixel -based" images. In fact, in some ways, the 1440x1080 images may actually look less digitized and slightly more "film-like" because of the rectangular pixels employed, but that purely subjective. In other words, sometimes let your eyes tell you which you prefer, not simply the specification sheets.
Posted by Robert A. Fowkes, May 16, 2008 9:08 AM
Reader Commentary I just wanted to clarify one item in the article. I realize that the way that a 1440x1080 image looks on a 1920x1080 display will depend a lot on how your scaling device (whether external or internal to the display) handles the 1440x1080 to 1920x1080 translation. However, in most cases this should not be a major issue unless the video processing is really bad. The main point of the article is that I don't consider the leap from 1440x1080 to 1920x1080 as great as, say, a 720p to 1080p display at close distances. While I would recommend a 1920x1080 camera for those buiyng new, you might find that there are some great buys in 1440x1080 hardware and it might meet you needs quite nicely if cost is a consideration while still being a "1080" device.... Does a high fidelity tweeter that goes from 5Khz to 35K hz sound better than one that goes from 5K to 25Khz? No you cannot make a decision on one peramiter....what is the most important thing is the signal to noise ratio. If your work is for birthday parties, children's plays, etc....the new baby etc it doesn't matter....I have 8mm analog Sony tapes that look better than JVC digital video tapes.... You make an interesting analogy (analogogy? <g>) and I understand your point (although there are those who would insist that those frequencies that are beyond the audible sound range contribute something to the audible sound). It all gets down to a question about what you are using a camera for. I had recently talked to an acquaintence who had just purchased a 1440x1080 HD digital camcorder and was bemoaning the fact that he had not waited for a new 1920x1080 HD camcorder because he was now "a generation behind." My response that he was worrying too much about what is really a minor difference in picture quality that he probably wouldn't even notice. This is what prompted my brief article. While resolution of digital images is producing the type of motion pictures that now make HD digital recording an affordable situation in a very small package some advances are significant and others are minor. I'm not disputing that analog recorders (or good old fashioned film cameras) ... Here's another take... > Is a 1440x1080 HD Camcorder Inferior to a 1920x1080 HD Camcorder? < Of course it is! That's a no-brainer... the 1920 HD camcorder has +33% greater horizontal resolution, and hence visible detail (during static scenes). Assuming, naturally, that all other factors are equal. The problem however is that all other factors are rarely (if ever) equal. For example, that 1920 vidcam may have a poorer quality lens on it, to achieve the same price point as the 1440 vidcam, and thus have a worse quality picture as a result. Resolution is only one characteristic of picture quality, and not necessarily the most important one. But it's easy to put on a spec sheet, and play a numbers game. Don't fall for it. > In other words, sometimes let your eyes tell you which you prefer, not simply the specification sheets. < I'd disagree w... Robert wrote: > ...because he was now "a generation behind." < You might want to ask him if he's ever seen the eye-popping, sharp, detailed, high-contrast video programming like 'Bikini Destinations' or 'Get Out' on HDNet, or some of the incredible nature documentaries on Discovery Home Theatre, on his big 1920x1080 screen. About as real as you can get, with loads of detail and almost 3-dimensional look. Oh, wait. All produced with 1440 HDcams. :shock: Too bad. So "last gen". ;) I need to e-mail Bennett Productions and let Casey and the crew know they need to dump all that old, obsolete 1440 gear, and get modernized. :D - Tim... I'd say always look beyond the spec sheets. They're useful to identify the list of features supported, but not the qualitative performance characteristics. Unless a product has received a review from an outside source that knows his stuff creating a real spec sheet you are correct. You CANNOT depend on manufacturers to tell you about performance, only sales and bragging rights.... Tim, I appreciate your input and, of course, agree with what you have stated. And your point is well taken that "always" is a more appropriate term than "sometimes" in this and most such cases. Well said. Apparently I should have called my article something like, "Is a 1920x1080 HD Camcorder really that much better than a 1440x1080 HD Camcorder?" or somthing like that to convey a better idea of what the content was. You are absolutely correct in pointing out that the performance of a camera involves much more than just the spec numbers of the image and similar. If such specs were the only factor then I would stop carrying around my Nikon D300 and rely solely on my pocket sized point and shoot 8.1 Megapixel Sony Cybershot unit! <g> Also, the fact that a static image will probably benefit the most from increased horizontal resolution and the fact that we are talking about motion pict... This whole thread has ignored the most important argument related to current technology 1440 vs 1920 HDCams, the use of MPEG2 vs MPEG4, and the resultant resolution of the final captured product. Case in point compare actual footage taken with the HDV Canon HV20/30 series against any 1920 MPEG4 HDCam out there, the realized resoultion results are similar. Two other points to consider are tape based HDV (1440) vs internal Hard Disk based HDCams (1920) as well as the ability to edit in MPEG2 vs MPEG4. MPEG2 holds up well against most of the MPEG4 cams out there and if your NLE doesn't support MPEG4 it's a moot point unless you wish to buy new software too. At first glance tapeless HDCams appear to have an advantage until you realize that eventually you'll have to store that data elsewhere. Whether it be on a RAID, bluray etc. you'll have pay to store the data. On the other hand miniDV tapes are relatively cheap, hold up well over time and aren't prone to disk drive failure. If y... Excellent points. Yes, there are several questions that need to be asked regarding High Definition camcorders and which specifications are really the most important (as is the case in most discussions on this forum). My original hypothesis was that people shouldn't obsess over a particular specification (in this case 1920 vs. 1440) at the expense of the overall picture (pun intended). As you stated, there are many factors to consider. And the issue of Hard Drive vs. tape based cameras has many sides to it as well. Yes, Hard Drive cameras are at a slight risk of Hard Drive failure but then we also have the possibility of tape jams in tape based equipment. The possibility of Hard Drive failure will become a moot point once large scale memory completely replaces the Hard Drive storage (coming faster than I would have thought). In addition, tape based camcorders require heavier transports and all the associated potential for problems so that's another data point to consider. And... More in Category: Technology
About Robert A. FowkesDr. Fowkes first started dabbling in computers and home electronics well over 50 years ago when he was a hobbyist building electronics and analog computers while in junior high school and well before the terms “Home Theater,” “High Definition” and “PC” were even a germ of an idea. After a long career as a Chemistry Teacher, Computer Coordinator and School Administrator, he has maintained an avid (some say obsessive) interest in computers and home electronics alike in retirement. As a frequent attendee of industry and enthusiast events and as a moderator on The Home Theater Forum, he remains actively involved and has developed a network of industry associations and friendships over the years. He thrives on the bleeding edge. His motto is, “The one who dies with the most toys wins!” Be sure to visit his Home Theater web site: The RAF Home Theater. |
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