Thursday, May 5, 2016

Computer screens: Glossary

DVI (Digital Visual Interface)
This interface is capable of handling the same video signals as HDMI. It does not allow, however, to process the audio portion of the signal. Although one can find some TVs equipped with this interface, it is typically reserved for monitors. Compared with VGA interfaces that long equip computer monitors, DVI input allows, provided your video card has a digital output, to transfer the video signal from the computer screen without use an analog conversion. The last tests we have made have clearly shown us that a digital connection between the computer and the screen significantly improves the picture quality (compared to the same image obtained via VGA analog input).

HDCP (High-Bandwidth Digital Content Protection)
Protocol to protect against copying high definition content. It is thus necessary to view a high-end definition image, for example, a Blu-ray DVD, the entire chain, graphics card, display ... is also compatible and supports HDCP.

HDMI (High Definition Multimedia Interface)
This interface that supports many video formats allows, among others, to transmit High Definition and his associate, all in digital. It is found on all televisions mentioning the High Definition on Blu-ray players, or on set-top boxes for receiving high definition transmitted via DTT.

We find increasingly that interface on monitors, even if the DVI is still more common in the computer field. It seems doomed to more or less long term, to replace the current SCART.

The term "resolution" here is a little unfair, this is actually the number of cells making up the LCD screen. It is generally given as the number of columns by number of lines (eg 1680 × 1050). This native resolution also provides information on screen format. For example, 1 680/1 050 = 1.6 is the resolution of a 16/10 screen, very common format in the 22-inch devices.

Contrast ratio
They are generally called "contrast" the ratio of the luminance (data in candela per square meter) between two successive beaches. Manufacturers refer to as "contrast ratio" value of contrast when one passes successively from the lowest luminance level (black) to the highest (white). As for the response time, measuring the contrast ratio is debatable, the methods used are far from homogeneous. A parameter that is actually irrelevant and of little interest to select a screen.

Colour temperature
It provides an overview of the colored pattern of a screen. There is talk of a warm color when it hits the red (around 2000 ° K) and cold as it approaches the blue (15,000 ° K). It is not uncommon for instructors offer different color temperatures depending on whether one is working on Excel or Word, as we watch a movie or we play. These preset color temperatures are generally accessible through the video menu.

Response time
Through measuring the time required to switch from one black level to a white level and a white level to a black level, this criterion is supposed to give you an idea of ​​the fluidity that you are expect your screen. The response time is a bit of a "cream pie" and together with the contrast ratio, one of the arguments that any seller will shake under your nose to recommend a product over another .

The only problem is you never know how this test is performed and manufacturers' information is generally unreliable. The measures response times we have achieved are far from those announced.

VGA (Video Graphics Array)
This is not entirely accurate, but usually this term that denotes the analog input of a monitor (VGA is actually a transmission mode associated with a resolution of 640 × 480 pixels, not a plug). The VGA connector, which consists of 15 pins is available on all computer screens, even if they are also equipped with a DVI or HDMI. Note, based on our test results, the quality of the image from the VGA input (analog information) is still significantly worse than following a DVI or HDMI input (digital information).

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