This article is part of a series designed to address your most common questions about LCD projectors. The intention is to use plain language to explain various features and complexities of projectors, to allow anyone (no matter how technically proficient) to use projectors effectively and efficiently. In this installment, we answer the question: What is 480p or progressive scan? Progressive scanning refers to the way images are projected. Think of a time when you clicked on a web link, and the images loaded one line at a time, from top to bottom. Because our brains process information very rapidly, progressive scanned images can cause us to feel bored or frustrated as we wait for the entire image to load. In many cases, short-attention span viewers can surf away, click off the site, or otherwise divert their attention, rather than waiting for the image to load. Alternatively, interlaced scanning is what occurs when you see a web image load in a low resolution manner, and then the image gradually becomes clearer. This produces a fast, low-res version of the image that quickly comes into sharper focus (thereby reducing the "boredom factor"). Essentially, what's happening in this case is that alternative lines are being loaded (for example, the first, third, fifth, seventh lines, etc.) then a second pass is made to "fill in" the remaining lines, making the image become much clearer and crisper. When it comes to projection technology, a fast progressive scan is desirable, so that images are loaded from top to bottom in the most efficient manner possible. For as quickly as an internet viewer can become bored and surf away, this is how quickly your audience members can grow bored with the graphics that supplement your oral presentation. That is why a very fast progressive scan is essential in projection technology. In the term "480p" the "p" stands for progressive scan (non-interlaced) and the number 480 refers to the vertical resolution. In other words, this technology can provide 480 vertically scanned lines per minute. Typically, 480p uses a horizontal resolution of 640 and a 4:3 aspect ratio. Sometimes, another number may appear after the "p" (such as 30 or 60) and this number would indicate the rate of progressive frames per second (how quickly each individual image can load). Technically speaking, 480p does not qualify as "high definition television" (HDTV); this is considered EDTV (enhanced definition television). If you're renting or borrowing a rental projector and your presentation is graphic-intense, be sure the projector you're using is at least 480p.
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