- About DVD
- Homemade DVDs
- Faster Editing Process
- DV Conquers the Big Screen
- HDTV: Where Does It Fit?
- Overview of New Digital Video Technology
This chapter is from the book
This chapter is from the book
This chapter is from the book
DV Conquers the Big Screen
With all the improvements of video technology, motion picture film still maintains a large visual quality edge over all current digital video formats. The best digital video cameras like the Canon XL1 or Sony VX2000 still deliver lower image quality than well-shot 16mm film, and there is no comparison when looking at 35mm film. The quality gap is shrinking, however.
New Star Wars Film Shot on Digital Video Camera
George Lucas is shooting the new Star Wars movie, Episode 2: Attack of the Clones, with a specially made Sony HD (high definition) digital video camera. The Sony HDW-F900 shoots at 24 progressive frames a second (24p) at 1,920_1,080 resolution. Keep in mind that the DV format by comparison captures video at 720_480 resolution.
Figure 3.7 The Sony HDW-F900 HD camcorder is being used exclusively to shoot the latest Star Wars prequel.
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Progressive video is a display format that shows complete frames of video. So each frame of progressive video looks like a normal complete picture (a "full field" would be the technical definition). Interlaced video, which current NTSC televisions use, operates with interlaced frames of video. In interlaced video fields half of the display lines have picture information, and the other half are empty. Every 1/60 of a second the empty field gets replaced with a new half field of video, and the old half field of video goes empty, and so on. If you were able to freeze your video picture and look very closely you would see an effect similar to when you look out a window through vertical blinds. Interlaced video became a technology standard because at the time there was a limited amount of broadcast bandwidth, and interlaced video allowed a picture to have twice the field rate (60 fields) compared to the same sized progressive format (allowing for a smoother picture). With sports particularly, smoothness is more important then picture clarity.
Most technology professionals prefer the look of progressive video because it has more clarity than interlaced video. In any case, because film is a progressive-based format, composed of 24 frames per second of 35mm pictures, progressive video at 24 frames per second (24p) makes sense as an appropriate film substitute.
Lucas claims that the quality differences between 35mm film and the footage he shot with his digital camera are indistinguishable on a large screen. While some might disagree, such an effects-heavy film is a good match for this bold experiment. Film audiences can decide for themselves whether they agree with Lucas when the movie is released. In any case, digital video is only going to get better in the future, so even if Lucas is misjudging, video quality will eventually surpass film.
Digital Video Projection Technology
While the new Star Wars film is being shot via digital video, it will eventually be transferred to film allowing for compatibility with your local movie theater's film projector. However, some day your local movie theater will display movies with a digital video projector. Predicting when this will happen would be unwise, but it will eventually happen as film technology only has image quality going for it now, and once that edge is lost film will become ancient history.
CRT Projection
CRT projectors are an analog technology. They utilize the same cathode tube hardware as boxy projection televisions (as well as standard TVs). They weigh 60 pounds and up, not exactly ideal for mounting to a ceiling. If set up properly, they can still deliver the best video picture currently available, but newer technology that is cheaper and lighter is about to pass them by (see Figure 3.8).
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Figure 3.8 If you can handle the size and price tag, the Runco DTV-873 CRT projector provides very good picture quality.
What is the current advantage of CRTs? Actual CRT tubes create the entire displayed picture (as opposed to a bright bulb projecting a smaller display—as is the case with LCD and DLP projectors), so the colors are less likely to be washed out. The most significant advantage of CRT is its ability to display dark tones correctly. On current non-CRT projectors, black often appears as dark gray. CRTs do have limited brightness capability; they max out around 260 lumens.
LCD Projection
LCD (liquid crystal display) projectors utilize the same technology used in flat screen monitors, commonly used in notebook computers. However, the LCD is quite a bit smaller, displaying a full resolution image that is projected with the use of a very bright light bulb and magnifying optics (see Figure 3.9).
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Figure 3.9 The Toshiba B2 LCD projector is excellent for business applications but not so good for movie playback.
LCD projectors are much cheaper than comparable CRT projectors and only weigh between five and ten pounds. LCD projectors can produce very sharp image quality if you sit far enough away, and are generally preferred for business presentations, as the sharpness is ideal for graphs, pie charts, and text. For movies they are less ideal, as they can suffer from pixelation, also known as the "screen door" effect. This means you can see the empty spaces between all the projected LCD pixels, so it can appear like you are looking through a screen door (see Figure 3.10).
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Figure 3.10 The screen door effect gets worse the closer to the LCD screen you are.
Anyone who has had enough notebooks or devices with LCDs knows that another problem that can arise is dead pixels, which can look kind of odd when projected on a large screen. Basically, this will cause black dots to appear on the displayed picture wherever there is a dead pixel (see Figure 3.11). Another problem with LCD projectors is that the bulbs only last between 1,000 and 2,000 hours and cost up to $500 to replace. These bulbs probably will get cheaper in the future.
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Figure 3.11 Dead pixels result in dead spots on your projected display that can be rather distracting.
The main advantage of LCDs is that many affordable models come with three LCD chips. Each one handles a single color (like a three-chip camcorder): red, green, and blue. Three-chip systems usually offer better color fidelity and resolution than one-chip systems. Due to reflectivity advantages, the brightest projectors are also LCDs.
DLP Projection
Developed by Texas Instruments, DLP projection is the newest and most promising display technology. DLP stands for digital light processing. DLP projectors use a small wafer chip called a DMD (Digital Micromirror Device) loaded with hundreds of thousands of tiny mirrors that can be controlled by electrical impulses. Each mirror, when positioned correctly, displays the appropriate color (see Figure 3.12).
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DLP projectors are even smaller than LCD projectors. Several models weigh less than three pounds. DLP projectors are also as inexpensive as LCD models. The main advantage of DLP besides size is image quality; they are far less prone to the screen door effect. As a result, the picture quality is usually much smoother, ideal for playback of DVD movies and home video. Currently, DLPs are the preferred projector for most new home theaters.
DLP projectors create images by reflecting light. This works well for producing colors but not as well for reproducing black. Consequently, this affects contrast performance (the difference between white and black) and black often appears as dark gray. However this problem has waned with each new generation of DLP. DLPs do produce dark colors better than LCD projectors. DLP projectors also have the same bulb life issues as LCD models.
Figure 3.12 This diagram illustrates how DLP works; the area marked DMD (Digital Micromirror Device) is where all the image-creating mirrors.