In digital imagery, pixels , pel , dots , or image elements are physical points in raster images, or elements the smallest address on all display devices that can be addressed; so it is the smallest controlled element of the image represented on the screen.
Each pixel is a sample of the original image; more samples usually provide a more accurate representation of the original. The intensity of each pixel is a variable. In color imaging systems, colors are usually represented by three or four intensity components such as red, green, and blue, or cyan, magenta, yellow, and black.
In some contexts (such as camera sensor description),
The pixel word is portmanteau pix (from "image", shortened to "pics") and el (for "element"); The formation is similar to 'i' el ' including the words voxel and texel .
Video Pixel
Etimologi
The word "pixel" was first published in 1965 by Frederic C. Billingsley of JPL, to illustrate the video image image elements of the spacecraft to the Moon and Mars. Billingsley has learned the word from Keith E. McFarland, in the General Precision Link Division in Palo Alto, who in turn says he does not know where it came from. McFarland said that it was "used at the time" (circa 1963).
The word is a combination of
The concept of "picture element" dates for the early days of television, for example as "Bildpunkt " (German word for pixel , literally 'dot' ') in German Pat. Nipkow. According to various etymologies, the earliest publications of the term drawing element itself were in the Wireless World magazine in 1927, although it has been used previously in various US patents filed as early as possible. 1911.
Some authors describe pixel as image cells, as early as 1972. In graphics and image and video processing, pel is often used instead of pixel . For example, IBM uses it in Technical Reference for the original PC.
Pixels, abbreviated as 'px,' are also commonly used measurement units in graphic and web design, equivalent to 1 / 96 inch (0 , 26 mm). This measurement is used to make sure the given element is displayed as the same size, no matter what screen resolution it sees.
Pixilation, spelled with the second i , is an unrelated filmmaking technique that starts with the beginning of the movie, where live actors are placed frame by frame and photographed to create stop-motion animations. An ancient English word meaning "possession by spirits (pixies)", this term has been used to describe the process of animation since the early 1950s; Various animators, including Norman McLaren and Grant Munro, are credited with popularizing it.
Maps Pixel
Technical
A pixel is generally regarded as the smallest single component of a digital image. However, this definition is very context sensitive. For example, there may be "printed pixels" on the page, or pixels carried by electronic signals, or represented by digital values, or pixels on display devices, or pixels in digital cameras (photosensor elements). The list is incomplete and, depending on the context, synonyms include pel, sample, byte, bit, dot, and spot. Pixels can be used as unit sizes such as: 2400 pixels per inch, 640 pixels per line, or spaced 10 separate pixels.
The size of dots per inch (dpi) and pixels per inch (ppi) is sometimes used interchangeably, but has different meanings, especially for printer devices, where dpi is a dot printer dot size (eg ink droplets) placement. For example, high quality photographic images can be printed with 600 ppi on a 1200 dpi inkjet printer. Higher dpi numbers, such as the 4800 dpi cited by printer manufacturers since 2002, do not mean much in terms of achievable resolution.
The more pixels used to represent the image, the closer the result can resemble the original. The number of pixels in an image is sometimes called a resolution, although the resolution has a more specific definition. The number of pixels can be expressed as one digit, as in a "three megapixel" digital camera, which has three million pixels nominal, or as a number pair, as in "640 by 480 views", which has 640 pixels from side to side and 480 from above down (as on a VGA screen), and therefore has a total of 640ÃÆ' â € "480 = 307,200 pixels or 0.3 megapixels.
Pixels, or color samples, that make up digital images (such as JPEG files used on web pages) may or may not be in one-to-one correspondence with screen pixels, depending on how the computer displays the image. In computing, images consisting of pixels are known as bitmapped images or raster images. The word raster is derived from a television scanning pattern, and has been widely used to describe the same halftone printing and storage techniques.
Sampling pattern
For convenience, pixels are usually set in a regular two-dimensional box. By using this setting, many common operations can be implemented by applying the same operations uniformly to each pixel independently. Other pixel settings are possible, with some sampling patterns even changing the shape (or kernel) of each pixel across the image. For this reason, care must be taken when getting images on one device and displaying them on another device, or when converting image data from one pixel format to another.
As an example:
- LCD screens typically use a staggered grid, in which red, green, and blue components are sampled in slightly different locations. Subpixel rendering is a technology that exploits these differences to improve text rendering on the LCD screen.
- Most color digital cameras use the Bayer filter, generating a regular pixel grid where colors each pixel depends on its position on the grid.
- The clipmap uses a hierarchical sampling pattern, in which the support size of each pixel depends on its location in the hierarchy.
- The curved grid is used when the underlying geometry is not planar, like the image of the earth from outer space.
- Unusual grid usage is an active research area, trying to cross the traditional Nyquist boundary.
- The pixels on a computer monitor are usually "square" (ie, have the same horizontal and vertical sampling pitch); pixels in other systems are often "rectangular" (that is, have horizontal and vertical sampling pitches that are not equal - length in shape), as well as digital video formats with various aspect ratios, such as anamorphic widescreen formats from Rec. 601 standard digital video.
Computer monitor resolution
Computers can use pixels to display images, often abstract images that represent the GUI. This image resolution is called the screen resolution and is determined by the computer's video card. LCD monitors also use pixels to display images, and have native resolution. Each pixel consists of a triad, with the number of triads assigning the original resolution. On some CRT monitors, the file sweep rate can be improved, resulting in native fixed resolution. Most CRT monitors do not have a fixed file cleaning rate, which means they have no native resolution at all - instead they have a well-supported set of resolutions. To produce the sharpest image possible on the LCD, the user must ensure the screen resolution of the computer matches the monitor's native resolution.
Telescope resolution
The pixel scale used in astronomy is the angular distance between two objects in the sky that drops one separate pixel on the detector (CCD or infrared chip). The measured s scale is radial pixel ratio p and the focal length f of the previous optical, i> = p/f . (The focal length is the product of the focus ratio by the diameter of the lens or corresponding mirror.) Since p is usually expressed in seconds of arc per pixel, since 1 radian is equal to 180/? * 3600? 206.265 arcseconds, and since the diameter is often given in millimeters and the pixel size in the micrometer produces another factor of 1.000, the formula is often quoted as s = 206p/f . Bits per pixel
The number of different colors that can be represented by pixels depends on the number of bits per pixel (bpp). Figure 1 bpp uses 1-bit for each pixel, so each pixel can be enabled or disabled. Each additional bit doubles the number of colors available, so a 2 bpp image can have 4 colors, and 3 bpp images can have 8 colors:
- 1 bpp, 2 1 = 2 colors (monochrome)
- 2 bpp, 2 2 = 4 colors
- 3 bpp, 2 3 = 8 colors
...
- 8 bpp, 2 8 = 256 colors 16 bpp, 2 16 = 65,536 colors ("Highcolor") 24 bpp, 2 24 = 16.777.216 colors ("Truecolor")
For color depths of 15 or more bits per pixel, the depth is usually the number of bits allocated for each of the red, green, and blue components. Highcolor, usually means 16 bpp, usually has five bits for red and blue respectively, and six bits for green, because the human eye is more sensitive to the green error than the other two primary colors. For applications involving transparency, 16 bits can be divided into five bits each red, green, and blue, with one bit left for transparency. 24-bit depth allows 8 bits per component. On some systems, 32-bit depths are available: this means that each 24-bit pixel has 8 extra bits to represent opacity (for merging purposes with other images).
Subpixel
Many display and image acquisition systems, for various reasons, are unable to display or feel different color channels on the same site. Therefore, the pixel grid is divided into single color areas that contribute to the colors that are displayed or felt when viewed remotely. In some displays, such as LCD, LED, and plasma displays, these single color areas are individually addressable elements, later known as subpixels . For example, LCDs typically divide each pixel vertically into three subpixels. When the square pixels are divided into three subpixels, each subpixel must be rectangular. In the display industry terminology, subpixels are often referred to as pixels , because they are the basic elements that can be addressed in hardware point of view, and hence pixel circuits rather than circuit subpixels is used.
Most digital camera image sensors use single-color sensor regions, such as using Bayer filter patterns, and in the camera industry known as pixels as in the display industry instead of subpixels .
For systems with subpixels, two different approaches can be taken:
- Subpixels can be skipped, with colorful pixels treated as the smallest addressable imaging element; or
- Subpixels may be included in rendering, which requires more analysis and processing time, but may produce images that appear to be superior in some cases.
This latter approach, referred to as subpixel rendering, uses the knowledge of pixel geometry to manipulate three colored subpixels separately, resulting in a noticeable increase in the resolution of the color display. While the CRT displays the use of the red-green-blue-masked phosphor area, dictated by a mesh grid called the shadow mask, it will require calibration steps that are difficult to juxtapose with the displayed pixel raster, and so the CRT does not currently use subpixel rendering.
The subpixel concept is related to the sample.
Megapixel
A megapixel (MP) is one million pixels; the term is used not only for the number of pixels in an image, but also to state the number of digital camera image sensor elements or the number of display elements of a digital display. For example, a camera that creates an image of 2048ÃÆ'â € "1536 pixels (3,145,728 pixels of final image) typically uses some additional lines and columns from the sensor elements and is generally said to have" 3.2 megapixel "or" 3.4 megapixel "depending on whether the number the reported number of "effective" or "total" pixels.
Digital cameras use photosensitive electronics, either a complementary charge-coupled (CCD) device or a complementary metal-oxide-semiconductor (CMOS) oxide, comprising a large number of single sensor elements, each of which records a measured intensity level. In most digital cameras, the sensor array is covered with a patterned color filter mosaic that has red, green, and blue areas in the Bayer filter arrangement, so that each sensor element can record the intensity of one primary color of light. The camera interpolates color information from adjacent sensor elements, through a process called demosaicing, to create the final image. These sensor elements are often called "pixels", although they only record 1 channel (just red, or green, or blue) from the final color image. Thus, two of the three color channels for each sensor must be interpolated and the so-called N-megapixel camera that produces N-megapixel images provides only one-third of the information generated by the same size image can be obtained from the scanner. Thus, certain color contrasts may look more opaque than others, depending on the allocation of primary colors (green has twice as many elements as red or blue in a Bayer setting).
DxO Labs invented the MegaPixel (P-MPix) Persuasion to measure the sharpness that a camera produces when paired to a particular lens - as opposed to a manufacturer MP for a camera product based solely on camera sensors. The new P-MPix claims to be a more accurate and relevant value for photographers to consider when sharpening the camera's sharpness. By mid 2013, the 35mm f/1.4 DIG HSM Sigma lens mounted on the Nikon D800 has the highest measured P-MPix. However, with a value of 23 MP, it still removes more than a third of the 36.3 MP D800 sensor.
One of the new methods to add Megapixels has been introduced in the Micro Four Thirds System camera that uses only 16MP sensors, but can generate 64MP RAW (40MP JPEG) by making two exposures, shifting sensors with half a pixel between them. By using a tripod to take multi-level snapshots in an instance, some 16MP images are then made into integrated 64MP images.
See also
References
External links
- A Pixel Is Not A Little Square: Microsoft Memo by computer graphics pioneer Alvy Ray Smith.
- Lyon talk video about pixel history in the Computer History Museum
- Non-Square Square and Pixels: Technical info on the pixel aspect ratio of modern video standards (480i, 576i, 1080i, 720p), plus software implications.
- 120 Megapixels are here now: Lots of information about MegaPixel and Gigapixel.
- How TV Work on Slow Motion - The Slow Mo Guys - YouTube Videos by The Slow Mo Guys
Source of the article : Wikipedia
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