Screen Size Comparison
In 2D screens, such as computer monitors and mobile phones, the size of the screen (also known as the viewport) is the physical size of the area where the images and videos are displayed. The size of the screen is usually described by the length of its diagonal, which is the distance between the opposite corners, usually in inches. It is also sometimes called the physical size of the image to distinguish it from the “logical size of the image”, which describes the resolution of the screen and is measured in pixels. Screen resolution vs pixel density The resolution or display modes of a digital TV, computer monitor or display device is the number of distinct pixels in each measure that can be displayed. This can be an ambiguous term, especially since the display resolution is controlled by various factors in cathode ray tubes (CRT), flat panel (including liquid crystal) and projection displays using fixed array imaging elements (pixels). For the display of devices such as phones, tablets, monitors and televisions, the use of the term display resolution, as defined above, is incorrect, although common. The term display resolution is commonly used to refer to pixel size, the maximum number of pixels in each measurement (e.g., 1920 × 1080), which says nothing about the pixel density of the display in which the image is actually formed: the resolution correctly refers to pixel density, the number of pixels per unit of distance or area, and not the total number of pixels. In digital measurements, the resolution of the display will be given in pixels per inch (PPI). In analog measurement, if the screen height is 10 inches, the horizontal resolution is measured in 10 square inches.f For television standards, this is usually indicated as “horizontal resolution lines by the height of the image”; for example, analog NTSC televisions can normally display about 340 lines “by the height of the image” of horizontal resolution from above-air sources, which is equivalent to about 440 common lines of actual image information from left to right. The history of “screen size” The method of measuring screen size along its diagonal was inherited from the method used in the first generation of CRT TVs, when circular edge photo tubes were widely used. Because they are round, the outer diameter of the bulb was used to describe its dimensions. As these round tubes were used to display rectangular images, the diagonal measurement of the visible rectangle was smaller than the diameter of the tube due to the thickness of the glass surrounding the phosphor screen (which was hidden from the viewfinder by the body and the bezel). This method continued even when the cathode ray tubes were made in the form of rounded rectangles; its advantage was that it was a unique number that determined the size and was not confusing when the aspect ratio was universal 4:3. In the USA, when almost all TV tubes had a 4:3 aspect ratio, the screen size was defined as the true diagonal of the screen with a V following it (this was a requirement in the USA market, but not in other countries). In almost all other markets, the outer diameter of the tube was specified. What was 27V in the USA may have been 28 inches elsewhere. However, in advertising in the USA the terminology V was often omitted, citing 27V as 27 inches. This was not misleading to the consumer because the law required the seller to specify the actual size of the screen. Flat panels, on the contrary, » Read More
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