A flash is a device used in photography producing a flash of artificial light at a color temperature of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene, other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs, modern cameras often activate flash units automatically. Flash units are built directly into a camera. Some cameras allow separate flash units to be mounted via an accessory mount bracket. In professional studio equipment, flashes may be large, standalone units, or studio strobes, studies of magnesium by Bunsen and Roscoe in 1859 showed that burning this metal produced a light with similar qualities to daylight. The potential application to photography inspired Edward Sonstadt to investigate methods of manufacturing magnesium so that it would burn reliably for this use and he applied for patents in 1862 and by 1864 had started the Manchester Magnesium Company with Edward Mellor.
It had the benefit of being a simpler and cheaper process than making round wire, mather was credited with the invention of a holder for the ribbon, which formed a lamp to burn it in. The packaging implies that the ribbon was not necessarily broken off before being ignited. An alternative to ribbon was flash powder, a mixture of powder and potassium chlorate, introduced by its German inventors Adolf Miethe. A measured amount was put into a pan or trough and ignited by hand, producing a brilliant flash of light, along with the smoke. This could be an activity, especially if the flash powder was damp. An electrically triggered flash lamp was invented by Joshua Lionel Cowen in 1899 and his patent describes a device for igniting photographers’ flash powder by using dry cell batteries to heat a wire fuse. Variations and alternatives were touted from time to time and a few found a measure of success in the marketplace, especially for amateur use. The use of powder in an open lamp was replaced by flashbulbs, magnesium filaments were contained in bulbs filled with oxygen gas.
Manufactured flashbulbs were first produced commercially in Germany in 1929, such a bulb could only be used once, and was too hot to handle immediately after use, but the confinement of what would otherwise have amounted to a small explosion was an important advance. A innovation was the coating of flashbulbs with a film to maintain bulb integrity in the event of the glass shattering during the flash
Film speed is the measure of a photographic films sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to measure the sensitivity of digital imaging systems, highly sensitive films are correspondingly termed fast films. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality, in short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the efficiency of the film or sensor. The speed of the emulsion was expressed in degrees Warnerke corresponding with the last number visible on the plate after development. Each number represented an increase of 1/3 in speed, typical speeds were between 10° and 25° Warnerke at the time. The concept, was built upon in 1900 by Henry Chapman Jones in the development of his plate tester. In their system, speed numbers were inversely proportional to the exposure required, for example, an emulsion rated at 250 H&D would require ten times the exposure of an emulsion rated at 2500 H&D.
The methods to determine the sensitivity were modified in 1925, the H&D system was officially accepted as a standard in the former Soviet Union from 1928 until September 1951, when it was superseded by GOST 2817-50. The Scheinergrade system was devised by the German astronomer Julius Scheiner in 1894 originally as a method of comparing the speeds of plates used for astronomical photography, Scheiners system rated the speed of a plate by the least exposure to produce a visible darkening upon development. ≈2 The system was extended to cover larger ranges and some of its practical shortcomings were addressed by the Austrian scientist Josef Maria Eder. Scheiners system was abandoned in Germany, when the standardized DIN system was introduced in 1934. In various forms, it continued to be in use in other countries for some time. The DIN system, officially DIN standard 4512 by Deutsches Institut für Normung, was published in January 1934, International Congress of Photography held in Dresden from August 3 to 8,1931.
The DIN system was inspired by Scheiners system, but the sensitivities were represented as the base 10 logarithm of the sensitivity multiplied by 10, similar to decibels. Thus an increase of 20° represented an increase in sensitivity. ≈3 /10 As in the Scheiner system, speeds were expressed in degrees, originally the sensitivity was written as a fraction with tenths, where the resultant value 1.8 represented the relative base 10 logarithm of the speed. Tenths were abandoned with DIN4512, 1957-11, and the example above would be written as 18° DIN, the degree symbol was finally dropped with DIN4512, 1961-10
It is not used in JPEG2000, PNG, or GIF. This standard consists of the Exif image file specification and the Exif audio file specification, the Japan Electronic Industries Development Association produced the initial definition of Exif. Version 2.1 of the specification is dated 12 June 1998, JEITA established Exif version 2.2, dated 20 February 2002 and released in April 2002. Version 2.21 is dated 11 July 2003, but was released in September 2003 following the release of DCF2.0, the latest, version 2.3, released on 26 April 2010 and revised in May 2013, was jointly formulated by JEITA and CIPA. Exif is supported by almost all camera manufacturers, the metadata tags defined in the Exif standard cover a broad spectrum and time information. Digital cameras will record the current date and time and save this in the metadata, a thumbnail for previewing the picture on the cameras LCD screen, in file managers, or in photo manipulation software. The Exif tag structure is borrowed from TIFF files, on several image specific properties, there is a large overlap between the tags defined in the TIFF, Exif, TIFF/EP, and DCF standards.
For descriptive metadata, there is an overlap between Exif, IPTC Information Interchange Model and XMP info, which can be embedded in a JPEG file, the Metadata Working Group has guidelines on mapping tags between these standards. When Exif is employed for JPEG files, the Exif data are stored in one of JPEGs defined utility Application Segments, the APP1, when Exif is employed in TIFF files, the TIFF Private Tag 0x8769 defines a sub-Image File Directory that holds the Exif specified TIFF Tags. Formats specified in Exif standard are defined as structures that are based on Exif-JPEG. When these formats are used as Exif/DCF files together with the DCF specification, their scope shall cover devices, recording media, the Exif format has standard tags for location information. As of 2014 many cameras and most mobile phones have a built-in GPS receiver that stores the information in the Exif header when a picture is taken. Some other cameras have a separate GPS receiver that fits into the connector or hot shoe.
The process of adding information to a photograph is known as geotagging. Photo-sharing communities like Panoramio, locr or Flickr equally allow their users to upload geocoded pictures or to add geolocation information online, Exif data are embedded within the image file itself. While many recent image manipulation programs recognize and preserve Exif data when writing to a modified image, many image gallery programs recognise Exif data and optionally display it alongside the images. The Exif format has a number of drawbacks, mostly relating to its use of file structures. For this reason most image editors damage or remove the Exif metadata to some extent upon saving, the standard defines a MakerNote tag, which allows camera manufacturers to place any custom format metadata in the file
A head is the part of an organism which usually includes the eyes, ears and mouth, each of which aid in various sensory functions such as sight, hearing and taste. Some very simple animals may not have a head, but many bilaterally symmetric forms do, heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nervous tissues concentrate at the anterior region, through biological evolution, sense organs and feeding structures concentrate into the anterior region, these collectively form the head. The human head is a unit that consists of the skull, hyoid bone. The term skull collectively denotes the mandible and the cranium, the skull can be described as being composed of the cranium, which encloses the cranial cavity, and the facial skeleton. There are eight bones in the cranium and fourteen in the facial skeleton, sculptures of human heads are generally based on a skeletal structure that consists of a cranium and cheekbone. Proponents of identism believe that the mind is identical to the brain, philosopher John Searle asserts his identist beliefs, stating the brain is the only thing in the human head.
Similarly, Dr. Henry Bennet-Clark has stated that the head encloses billions of miniagents and microagents, evolution of the head In the vertebrates has occurred by the fusion of a fixed number of anterior segments, in the same manner as in other ”heteronomously segmented animals”. In some cases segments or a portion of the segments disappear, the head segments lose most of its systems except for the nervous system. In some arthropods, especially trilobites, the cephalon, or cephalic region, is the region of the head which is a collective of fused segments, a typical insect head is composed of eyes and components of mouth. As these components differ substantially from insect to insect, they form important identification links, eyes in the head found, in several types of insects, are in the form of a pair of compound eyes with multiple faces. In many other types of insects the compound eyes are seen in a facet or group of single facets. In some case, the eyes may be seen as marks on the dorsal or located near or toward the head, antennae on the insects head is found in the form of segmented attachments, in pairs, that are usually located between the eyes.
These are in varying shapes and sizes, in the form of filaments or in different enlarged or clubbed form, insects have mouth parts in various shapes depending on their feeding habits. Labrum is the lip which is in the front area of the head and is the most exterior part. A pair of mandible is found on backside of the labrum flanking the side of the mouth, at the back side of the mouth is the labium or lower lip. There is a mouth part in some insects which is termed as hypopharynx which is usually located between the maxillac. The heads of humans and other animals are commonly recurring charges in heraldry, several varieties of womens heads occur, including maidens heads, ladies heads, nuns heads, and occasionally queens heads
In photography and image processing, color balance is the global adjustment of the intensities of the colors. An important goal of this adjustment is to specific colors – particularly neutral colors – correctly. Hence, the method is sometimes called gray balance, neutral balance. Color balance changes the mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to change them for effect. Image data acquired by sensors – either film or electronic image sensors – must be transformed from the values to new values that are appropriate for color reproduction or display. In film photography, color balance is achieved by using color correction filters over the lights or on the camera lens. It is particularly important that neutral colors in a scene appear neutral in the reproduction, most digital cameras have means to select color correction based on the type of scene lighting, using either manual lighting selection, automatic white balance, or custom white balance.
The algorithms for these processes perform generalized chromatic adaptation, many methods exist for color balancing. Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting, another option on some cameras is a button which one may press when the camera is pointed at a gray card or other neutral colored object. This captures an image of the ambient light, which enables a digital camera to set the color balance for that light. There is a literature on how one might estimate the ambient lighting from the camera data. A variety of algorithms have been proposed, and the quality of these has been debated, a few examples and examination of the references therein will lead the reader to many others. Examples are Retinex, a neural network or a Bayesian method. Color balancing an image not only the neutrals, but other colors as well. An image that is not color balanced is said to have a color cast, Color balancing may be thought in terms of removing this color cast.
Color balance is related to color constancy. Algorithms and techniques used to color constancy are frequently used for color balancing
A color space is a specific organization of colors. In combination with physical device profiling, it allows for reproducible representations of color, for example, Adobe RGB and sRGB are two different absolute color spaces, both based on the RGB color model. When defining a color space, the reference standard is the CIELAB or CIEXYZ color spaces. For example, although several specific color spaces are based on the RGB color model, colors can be created in printing with color spaces based on the CMYK color model, using the subtractive primary colors of pigment. The resulting 3-D space provides a position for every possible color that can be created by combining those three pigments. Colors can be created on computer monitors with color spaces based on the RGB color model, a three-dimensional representation would assign each of the three colors to the X, Y, and Z axes. Note that colors generated on given monitor will be limited by the medium, such as the phosphor or filters. Another way of creating colors on a monitor is with an HSL or HSV color space, based on hue, with such a space, the variables are assigned to cylindrical coordinates.
Many color spaces can be represented as three-dimensional values in this manner, but some have more, or fewer dimensions, Color space conversion is the translation of the representation of a color from one basis to another. The RGB color model is implemented in different ways, depending on the capabilities of the system used, by far the most common general-used incarnation as of 2006 is the 24-bit implementation, with 8 bits, or 256 discrete levels of color per channel. Any color space based on such a 24-bit RGB model is limited to a range of 256×256×256 ≈16.7 million colors. Some implementations use 16 bits per component for 48 bits total and this is especially important when working with wide-gamut color spaces, or when a large number of digital filtering algorithms are used consecutively. The same principle applies for any color space based on the color model. CIE1931 XYZ color space was one of the first attempts to produce a space based on measurements of human color perception. The CIERGB color space is a companion of CIE XYZ.
Additional derivatives of CIE XYZ include the CIELUV, CIEUVW, RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. RGB stores individual values for red and blue, RGBA is RGB with an additional channel, alpha, to indicate transparency. Common color spaces based on the RGB model include sRGB, Adobe RGB, ProPhoto RGB, scRGB, one starts with a white substrate, and uses ink to subtract color from white to create an image
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a focal length has greater optical power than one with a long focal length. For a thin lens in air, the length is the distance from the center of the lens to the principal foci of the lens. For a converging lens, the length is positive, and is the distance at which a beam of collimated light will be focused to a single spot. For a diverging lens, the length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens. The focal length of a lens can be easily measured by using it to form an image of a distant light source on a screen. The lens is moved until an image is formed on the screen. In this case 1/u is negligible, and the length is given by f ≈ v. Back focal length or back focal distance is the distance from the vertex of the last optical surface of the system to the focal point.
For an optical system in air, the focal length gives the distance from the front. If the surrounding medium is not air, the distance is multiplied by the index of the medium. Some authors call these distances the front/rear focal lengths, distinguishing them from the front/rear focal distances, defined above. In general, the length or EFL is the value that describes the ability of the optical system to focus light. The other parameters are used in determining where an image will be formed for an object position. The quantity 1/f is known as the power of the lens. The corresponding front focal distance is, FFD = f, in the sign convention used here, the value of R1 will be positive if the first lens surface is convex, and negative if it is concave. The value of R2 is negative if the surface is convex
Panasonic Corporation, formerly known as Matsushita Electric Industrial Co. Ltd. is a Japanese multinational electronics corporation headquartered in Kadoma, Japan. The company was founded in 1918 and has grown to one of the largest Japanese electronics producers alongside Sony, Toshiba. In addition to electronics, it offers non-electronic products and services such as home renovation services, Panasonic is the worlds fourth-largest television manufacturer by 2012 market share. Panasonic has a listing on the Tokyo Stock Exchange and is a constituent of the Nikkei 225. It has a listing on the Nagoya Stock Exchange. From 1935 to October 1,2008, the name was Matsushita Electric Industrial Co. Ltd. On January 10,2008, the announced that it would change its name to Panasonic Corporation, in effect on October 1,2008. The name change was approved at a meeting on June 26,2008 after consultation with the Matsushita family. Panasonic was founded in 1918 by Kōnosuke Matsushita as a vendor of duplex lamp sockets, in 1927, it began producing bicycle lamps, the first product which it marketed under the brand name National.
After the war, Panasonic regrouped as a Keiretsu and began to supply the boom in Japan with radios and appliances. Matsushitas brother-in-law, Toshio Iue, founded Sanyo as a subcontractor for components after World War II, Sanyo grew to become a competitor to Panasonic, but was acquired by Panasonic in December 2009. In 1961, Konosuke Matsushita traveled to the United States and met with American dealers, the company began producing television sets for the U. S. market under the Panasonic brand name, and expanded the use of the brand to Europe in 1979. The company used the National brand outside of North America from the 1950s to the 1970s, the company developed a line of home appliances such as rice cookers for the Japanese and Asian markets. Rapid growth resulted in the company opening manufacturing plants around the world, the company debuted a hi-fidelity audio speaker in Japan in 1965 with the brand Technics. This line of high quality stereo components became worldwide favorites, the most famous products being its turntables, such as the SL-1200 record player, known for its high performance and durability.
In 1973, Matsushita formed a joint venture with Anam Group, in 1983, Matsushita launched the Panasonic Senior Partner, the first fully IBM PC compatible Japanese-made computer. In November 1990, Matsushita agreed to acquire the American media company MCA Inc. for US$6.59 billion, Matsushita subsequently sold 80% of MCA to Seagram Company for US$7 billion in April 1995. In 1998, Matsushita sold Anam National to Anam Electronics, on May 2,2002, Panasonic Canada marked its 35th anniversary in that country by giving $5-million to help build a music city on Torontos waterfront
In photography, the term acutance describes a subjective perception of sharpness that is related to the edge contrast of an image. Acutance is related to the amplitude of the derivative of brightness with respect to space, due to the nature of the human visual system, an image with higher acutance appears sharper even though an increase in acutance does not increase real resolution. Historically, acutance was enhanced chemically during development of a negative, in the example image, two light gray lines were drawn on a gray background. As the transition is instantaneous, the line is as sharp as can be represented at this resolution, acutance in the left line was artificially increased by adding a one-pixel-wide darker border on the outside of the line and a one-pixel-wide brighter border on the inside of the line. The actual sharpness of the image is unchanged, but the apparent sharpness is increased because of the greater acutance. In this somewhat overdone example most viewers will be able to see the borders separately from the line, several image processing techniques, such as unsharp masking, can increase the acutance in real images.
Low-pass filtering and resampling often cause overshoot, which increases acutance, but can reduce absolute gradient and resampling can cause clipping and ringing artifacts. An example is bicubic interpolation, widely used in processing for resizing images. Thus the acutance of an image is a vector field, coarse grain or noise can, like sharpening filters, increase acutance, hence increasing the perception of sharpness, even though they degrade the signal-to-noise ratio
Colorfulness or saturation in colorimetry and color theory refers to the perceived intensity of a specific color. Colorfulness is the visual sensation according to which the color of an area appears to be more or less chromatic. Chroma is the relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting. Therefore, chroma should not be confused with colorfulness, saturation is the colorfulness of a color relative to its own brightness. A highly colorful stimulus is vivid and intense, while a less colorful stimulus appears more muted, with no colorfulness at all, a color is a “neutral” gray. Any color can be described using three color appearance parameters — colorfulness and hue, saturation is one of three coordinates in the HSL and HSV color spaces. The saturation of a color is determined by a combination of light intensity, the purest color is achieved by using just one wavelength at a high intensity, such as in laser light. If the intensity drops, as a result the saturation drops, to desaturate a color of given intensity in a subtractive system, one can add white, gray, or the hues complement.
CIELUV The chroma normalized by the lightness, s u v = C u v ∗ L ∗ =132 +2 where is the chromaticity of the white point, and chroma is defined below. Nevertheless, this provides a reasonable predictor of saturation. S a b = C a b ∗ C a b ∗2 + L ∗2100 % where Sab is the saturation, L* the lightness and C*ab is the chroma of the color. CIECAM02 The square root of the colorfulness divided by the brightness, M is proportional to the chroma C, thus the CIECAM02 definition bears some similarity to the CIELUV definition. An important difference is that the CIECAM02 model accounts for the conditions through the parameter FL. Different color spaces, such as CIELAB or CIELUV may be used, the naïve definition of saturation does not specify its response function. However, both color spaces are nonlinear in terms of perceived color differences. It is possible—and sometimes desirable—to define a quantity that is linearized in term of the psychovisual perception. The transformation of to is given by, C a b ∗ = a ∗2 + b ∗2 h a b = arctan b ∗ a ∗ and analogously for CIE L*C*h.
The chroma in the CIE L*C*h and CIE L*C*h coordinates has the advantage of being more psychovisually linear, and therefore, chroma in CIE1976 L*a*b* and L*u*v* color spaces is very much different from the traditional sense of saturation
In photography, the metering mode refers to the way in which a camera determines the exposure. Cameras generally allow the user to select between spot, center-weighted average, or multi-zone metering modes, various metering modes are provided to allow the user to select the most appropriate one for use in a variety of lighting conditions. With spot metering, the camera will only measure a small area of the scene. This will by default be the centre of the scene. The user can select a different off-centre spot, or to recompose by moving the camera after metering. The first spot meter was built by Arthur James Dalladay, editor of The British Journal of Photography in about 1935, a few models support a Multi-Spot mode which allows multiple spot meter readings to be taken of a scene that are averaged. Some cameras, the OM-4 and T90 included, support metering of highlight, spot metering is very accurate and is not influenced by other areas in the frame. It is commonly used to very high contrast scenes.
The area around the back and hairline will become over-exposed, spot metering is a method upon which the Zone System depends. In many cases the camera will over or underexpose, when using the spot mode, modern cameras tend to find the correct exposure precisely. In complex light situations though, professional photographers tend to switch to manual mode, another example of spot metering usage would be when photographing the moon. Due to the dark nature of the scene, other metering methods tend to overexpose the moon. Spot metering will allow for more detail to be out in the moon while underexposing the rest of the scene. More commonly, spot metering is used in photography, where the brightly lit actors stand before a dark or even black curtain or scrim. Spot metering only considers the actors in this case, while ignoring the overall darkness of the scene, in this system, the meter concentrates between 60 to 80 percent of the sensitivity towards the central part of the viewfinder. The balance is feathered out towards the edges, some cameras will allow the user to adjust the weight/balance of the central portion to the peripheral one.
When moving the point off center the camera will proceed as above. Although promoted as a feature, center-weighted metering was originally a consequence of the meter cell reading from the screen of SLR cameras
Factors considered may include unusual lighting distribution, variations within a camera system, non-standard processing, or intended underexposure or overexposure. Cinematographers may apply exposure compensation for changes in angle or film speed. Most DSLR cameras have a display whereby the photographer can set the camera to either over or under expose the subject by up to three f-stops in 1/3rd stop intervals. Each number on the scale represents one f-stop, decreasing the exposure by one f-stop will halve the amount of light reaching the sensor, the dots in between the numbers represent 1/3rd of an f-stop. In photography, some cameras include exposure compensation as a feature to allow the user to adjust the automatically calculated exposure, camera exposure compensation is commonly stated in terms of EV units,1 EV is equal to one exposure step, corresponding to a doubling of exposure. Exposure can be adjusted by changing either the lens f-number or the exposure time, if the mode is aperture priority, exposure compensation changes the exposure time, if the mode is shutter priority, the f-number is changed.
If a flash is being used, some cameras will adjust it as well, the earliest reflected-light exposure meters were wide-angle, averaging types, measuring the average scene luminance. When measuring a scene with atypical distribution of light and dark elements, or an element that is lighter or darker than a middle tone. For example, a scene with predominantly light tones often will be underexposed and that both scenes require the same exposure, regardless of the meter indication, becomes obvious from a scene that includes both a white horse and a black horse. A photographer usually can recognize the difference between a horse and a black horse, a meter usually cannot. When metering a white horse, a photographer can apply exposure compensation so that the horse is rendered as white. Many modern cameras incorporate metering systems that measure scene contrast as well as average luminance, in scenes with very unusual lighting, these metering systems sometimes cannot match the judgment of a skilled photographer, so exposure compensation still may be needed.
An early application of compensation was the Zone System developed by Ansel Adams. Developed for black-and-white film, the Zone System divided luminance into 11 zones, with Zone 0 representing pure black, the meter indication would place whatever was metered on Zone V, a medium gray. The meter indication, remains Zone V, the Zone System is a very specialized form of exposure compensation, and is used most effectively when metering individual scene elements, such as a sunlit rock or the bark of a tree in shade. Many cameras incorporate narrow-angle spot meters to facilitate such measurements, because of the limited tonal range, an exposure compensation range of ±2 EV is often sufficient for using the Zone System with color film and digital sensors. Exposure value Exposure index Light meter Zone System Exposure bracketing Auto Exposure Bracketing