In a world where visual-based information passes fluidly between handsets, monitors, digital signage, and projector installations, the quality and integrity of the colors that channel our information is starting to change the way manufacturers engineer visual display products.
Within most screen-based devices, color accuracy is already being observed across different units, meaning users obtain the exact same color experience when viewing a film on a tablet or a smart TV. However, within industries such as projection, manufacturers are beginning to place more emphasis on delivering consistent colors to the screen.
Typically, the marketplace has shied away from color accuracy in favor of brightness, which uses factors such as lumen count and resolution to measure quality. However, as companies push brightness levels higher and higher, they are also affecting color quality by releasing hints of green onto the screen.
Since green measures higher on lumens meters, this method creates the false impression of higher brightness.
sRGB and Color Performance
To ensure that consumers obtain the best possible color performance, some projector manufacturers are now using sRGB (standard Red, Green, Blue) as the default setting on their products.
Using RGB primary colors with a specific gamma curve, sRGB also renders practically all content on the Internet. While most projectors manufacturers do include a sRGB mode, it remains limited as an option — meaning users will still need to navigate through menus in order to correctly display colors.
Furthermore, these manual adjustments will only display up to 70- or 80-percent of the sRGB spectrum — which fails to meet full color integrity standards.
As a rule, an image or video captured in sRGB should be reproduced on the Internet, viewed on a monitor, or printed on paper with the same color integrity as the moment it was taken. When a projector is part of this workflow, the result should be no different.
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While content is usually created with the consumption device in mind, several factors can still adversely affect color.
Factors That Affect Image Quality
There are several elements which come into play when measuring color. Brightness is what is perceived by the human eye, while luminance refers to a unit of measurement to quantify light. The projector industry uses both terms interchangeably but there are differences when it comes to color quality.
With luminance, a meter measures the power of projected white light at its maximum output level. However, when a projector illuminates an entire screen, the light reflected to the eye is labeled as brightness.
Contrast is the range of brightness levels as well as dark levels in a projected image. With high contrast levels, image details become more discernible to the viewer.
Different types of contrast measurements include on/off contrast, which measures the brightness of a full white screen versus an entirely black screen; dynamic contrast, which uses an iris inserted in the light path as a measuring tool; and system contrast which uses a checkboard pattern to measure luminance from different perspectives.
Because system contrast takes light output, a projector’s inherent contrast, the size and gain of the screen, and ambient light into account, this method offers the more representative measure for indicating actual contrast levels.
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As they age, projectors begin to show variations in color quality due to two primary factors: lamp usage and color fading. Almost all projectors are equipped with lamps which will eventually decline to 50-percent of their original brightness, at which point they will need to be replaced.
Image fading is the projector’s ability to adequately render colors due to the deterioration of internal components. Occurring slowly over time, fading reduces contrast levels — making it more difficult for viewers to distinguish dark and light pixels within images, blending green and yellow color tints, and making blue colors disappear as they begin to fade into greens.
Another critical issue with fading is the loss of a projector’s ability to properly replicate accurate white points, which impacts other colors in the process. While color fading most affects projectors using non-DLP technology, the ability to show authentic color over time is a key value point for both end users and installers.
Considerations for Commercial Integrators
The ability to deliver color integrity and accuracy reduces maintenance, increases installation flexibility, and allows integrators to offer more quality-driven setups. This value also opens new sales and setup opportunities within creative industries where accurate color representation is paramount to results.
Manufacturers should also consider equipping display devices with adequate color capabilities straight from the box — giving consumers, educators, creative professionals, and educators the capability to display content the way it was intended to be seen.
Felix Pimentel is the field application engineer for BenQ America Corp.
