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Contrast As defined, contrast is the difference or ratio between the maximum brightness (white) and minimum brightness (black). Perhaps more than any other spec in the universe of consumer electronics, contrast (contrast ratio) is the most misleading and exaggerated of them all. The reason for this is because there is no universally accepted method or standard for measuring actual contrast ratio, and as such, manufacturers take swift advantage of this, using stacked or overly-advantageous methods that will yield higher numbers, even if they have no basis in real world application and what you and I will actually be watching. They simply ascribe to the theory that the bigger the number, the greater sales, and quite often, this is the case for the buying public at large. When contrast is adjusted to just the right levels, the image sees an increase in resolution and a far greater depth of field. While as mentioned, brightness controls black levels, on the other hand, contrast controls white levels. And the interplay between these two is very important, as the higher your brightness or contrast ratio ratings are, the blacker your blacks are. For instance, if a display product is rated with a contrast ratio of 3000:1, it essentially means that your white level is 3000 times brighter than your black level. In theory, the greater the gap between these two figures, the more richly detailed your image. But as our next section below will outline, it’s not only a high contrast ratio that determines the depth of an image’s details, as we must also consider something known as gray-scale performance.
Gray-Scale Gray-scale is a pattern consisting of various shades of neutral gray, with the darkest possible shade (weakest intensity) being black, and the lightest possible shade (strongest intensity) being white. Let’s assume you have a product with an astronomically high contrast ratio advertised at 50,000:1. For starters, you've been lied to. Quite egregiously as well. But taking this at face value, it would be quite easy and even logical to say and expect a very richly detailed image. But alas, there’s more to it than just that. The reason being is this: even if your black level is 50,000 times darker than your white level, what about all the shades of gray in between these two? If a projector or television has a perfectly black black and a perfectly white white, but lacks a comprehensive gray-scale (which essentially acts as the gradual link between these two), your picture will still be lacking in detail, and a smoothly rendered, three-dimensional quality. While this isn’t exactly the sexy spec du jour that manufacturers reference or advertise, one could argue that gray-scale is as important, if not more important, than contrast ratio, and in many ways, is one of the more integral contributing factors to overall image quality. Color or Color Saturation Simply defined, color or color saturation is the purity or intensity of a given color. The greater the purity or intensity, the more accurate or authentic the color ultimately is. The relevance of this fairly self-explanatory: if your display’s colors are lacking in the necessary saturation levels, your picture – while it may still be rich and detailed – will not be a realistic representation of the source image and how it was intended to be viewed. Think of Ferrari red, IBM blue, or Pizza Pizza orange. If the color saturation is off, while you’ll still see red, blue, or orange, it won’t quite be the proper, trademark shade of each.
Color Gamut This refers to the range of colors that a product such as a television or a projector can display. Not unlike color saturation, this is also self-explanatory: the greater your color gamut range, the more available colors your product can display at any given time. So when you need your projector or HD TV to render that achingly beautiful sunset overlooking the lake, or whatever other cinematic image you happen upon, the more colors available, the more detailed and smooth your image will be. When a TV or a projector has a limited color gamut, one thing you may notice is color banding. This is where you can see where one color begins and ends in relation to the next color or shade of color it’s connected to. We don’t see this in real life, so the aim of any quality display product is to keep things as rich and authentic as possible. A limited color gamut will also result in colors or shades of colors being "off" or less detailed, thereby resulting in an image not being rendered correctly and true to its source image.
Gamma Inter-related to brightness, gamma and gamma correction is the process which refers to properly controlling the overall brightness of an image. This assures that the image you’re watching isn’t too dark or too bright. As a general rule of thumb, industry experts recommend a 2.2 gamma correction for NTSC video, and a 2.5 gamma correction for HDTV. These numbers and the like refer to the voltage response curve of your display, and how it perceives and renders a given image that it receives. In laymen’s terms, because things (image signals) get lost in translation, we need to compensate (gamma correct) for this so that we’re seeing the image in it’s most proper and natural state.
Resolution Resolution is the numbers of pixels (individual color points) displayed on the horizontal and vertical axis, i.e., 1920 x 1080. The greater the displayable resolution, the more detailed your images will be, as there are essentially less gaps or pixilated blocks of indistinguishable detail in the picture. But there’s more to it than just that: the smaller the display (screen size), the sharper the image appears, but when you begin to increase the size of your display, while the resolution remains the same, the sharpness decreases because those very same pixel dimensions are now being asked to spreads themselves out over a larger canvas, if you will. This is somewhat similar to when you physically move closer or further away from your screen. The closer you get, the more pixels you’ll see, while the further you get, the more detailed and cohesive an image you’ll see, not unlike viewing a painting, just replacing the pixels for paint. Current high-definition standards are as follows: 720p 1280 x 720 pixels (progressive) When you hear progressive or progressive scan, this simply means that an image and all of the lines comprising its frame are drawn in sequence, whereas with interlaced images, first the odd lines of each frame are drawn, and then the even lines. Tint Tint can be defined as the mixture of a color with white or black, thereby either increasing the lightness in the case of white, or decreasing it in the case of black. Think of tints on a car; the more black you add, the darker the tint (glass) becomes. In relation to most displays these days, the tint (or hue) when properly adjusted will allow for more accurate flesh tones that strike the perfect balance between the pale white ghost a la Casper, and the overly-orange tanned torso that would make even George Hamilton gasp in horror. Sharpness Sharpness refers to the clarity of an image. Sharpness was initially conceived to add a bit of the high frequency picture detail to images that were lost with older style displays. These days, most modern displays utilize a 3-D comb filter which preserves all that high frequency detail, but you still need to be aware of how you adjust for sharpness, as you can quite easily wind up with an image with increased distortion or decreased resolution. Simply stated though, the sharper an image, the clearer the details it can display. In instances where you’re watching a movie or a sporting event with optimal sharpness, rather than just seeing patches or large chunks of pixilated blocks, and blurry, undefined shapes, you begin to see all the fine, subtle details that comprise an image such as each strand of grass or hair, the stitching on a logo or a football, or the very fabric of one’s clothes. I could go on and on, but you get the point: sharpness equals detail and texture, and detail and texture equals a far better image.
Conclusion As you may have already gathered, there is no one, single solitary thing that makes a picture great, just as there is no one thing that works completely independent from other things. In the world of contemporary displays that include projectors (DLP and LCD) and televisions (LCD and plasma), many things have to work in happy unison, and it’s the art and science of striking this very fine balance between things such a contrast, brightness, color, sharpness, and tint that will ultimately determine the quality of the image.
All images taken with the Nikon D40 from BBC's Planet Earth with a Sony PS3 for HD, Blu-ray playback, via an HDMI connection, 1080p output, the Epson 1080 projector, and the Draper 106-Inch HD Onyx Gray Screen.
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