Color accuracy went south with the introduction of LCDs. Fortunately, the TV industry has made significant strides since then. The latest high-end LED-backlit LCDs—and of course OLED TVs—produce noticeably more accurate color than previous generations. They produce reds that are actually red, for example, and not dark orange.
In this, the third installment in our series that cuts through the BS that is routinely used to market new televisions, we define the terms, standards, and specs involving color. In case you missed the first two installments, you can use either the navigation tools above and at the end of the story, or you can go directly to our discussion of screen size, resolution, and refresh speed, and our explanations of display types and technologies.
Adobe RGB: A color standard/space implemented to roughly match the spectrum attained by the paper and ink world’s CMYK (Cyan, Magenta, Yellow, and blacK). TV vendors will use Adobe RGB as a point of comparison, which is fine for HDTV; but for Ultra HD (popularly—if not entirely accurately—described as 4K), look for comparisons to Rec.2020. Adobe RGB covers more colors than sRGB, but fewer than Rec.2020.
Color depth (aka bit depth): The number of bits in a digital video signal that are used for each color component of a single pixel. With 8-bit color, there are three bits for the red component, three bits for green, and two bits for blue (3:3:2). Why only two bits for blue? Because the human eye is less sensitive to the blue component of color. (See also: Deep Color and True Color, below.)
Color space: The range—or gamut—of colors a video display can produce. There are various color-space standards, but the ones most commonly associated with TVs are—from narrowest to broadest—are sRGB, from Rec. 709 (from the HDTV spec); Adobe RGB; and Rec. 2020 (from the Ultra HD spec). Vendors will say their TV meets N percentage of X space.
This graph illustrates three color spaces: HDTV (the smallest triangle), Rec. 2020, and the color space that Nanosys, Inc.'s says its quantum dot technology can deliver (superimposed on the other two). (Click to expand). Credit: Nanosys, Inc.
Deep Color: 30-, 36-, or 48-bit color depth. A digital video signal supporting Deep Color uses 10-, 12- or 16 bits for each of the red, green, and blue components of a pixel to deliver billions of colors. The HDMI spec supports Deep Color starting with HDMI 1.3. (See also: Color depth, above.)
High Dynamic Range (HDR): This simply means lighter lights, darker darks (by comparison) and, as a result, more range in between. In today’s TV market, HDR is more a result than a standard for accomplishing it. You’ll see it labeled X-Tended Dynamic range (Sony), Ultra Luminance (LG), or even the ostentatious Peak Illuminator Ultimate (Samsung). Vizio simply uses Dolby’s Dolby Vision. Only Panasonic calls it HDR. It’s generally accomplished by making the screen brighter, e.g. 800- versus the 400 nits that’s common in the current generation of TVs. You’ll find a deeper exploration of high-dynamic-range TVs here. (Note: Don’t confuse this definition of HDR with the HDR used in photography, where different levels of exposure are combined to produce an image with a wider range of brightness and contrast.)
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