LCD

A liquid crystal display (commonly abbreviated LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It is prized by engineers because it uses very small amounts of electric power, and is therefore suitable for use in battery-powered electronic devices.

Batteries

Digital cameras have high power requirements, and over time have become increasingly smaller in size, which has resulted in an ongoing need to develop a battery small enough to fit in the camera and yet able to power it for a reasonable length of time.

Essentially two broad divisions exist in the types of batteries digital cameras use.

Off-the-shelf

The first is batteries that are an established off-the-shelf form factor, most commonly AA, CR2, or CR-V3 batteries, with AAA batteries in a handful of cameras. The CR2 and CR-V3 batteries are lithium based, and intended for single use. They are also commonly seen in camcorders. The AA batteries are far more common; however, the non-rechargeable alkaline batteries are capable of providing enough power for only a very short time in most cameras. Most consumers use AA Nickel metal hydride batteries (NiMH) (see also chargers and batteries) instead, which provide an adequate amount of power and are rechargeable. NIMH batteries do not provide as much power as lithium ion batteries, and they also tend to discharge when not used. They are available in various ampere-hour (Ah) or milli-ampere-hour (mAh) ratings, which affects how long they last in use. Typically mid-range consumer models and some low end cameras use off-the-shelf batteries; only a very few DSLR cameras accept them (for example, Sigma SD10). Rechargeable RCR-V3 lithium-ion batteries are also available as an alternative to non-rechargeable CR-V3 batteries.

Proprietary

The second division is proprietary battery formats. These are built to a manufacturer's custom specifications, and can be either aftermarket replacement parts or OEM. Almost all proprietary batteries are lithium ion. While they only accept a certain number of recharges before the battery life begins degrading (typically up to 500 cycles), they provide considerable performance for their size. A result is that at the two ends of the spectrum both high end professional cameras and low end consumer models tend to use lithium ion batteries.

Memory Stick

Memory Stick (sometimes abbreviated as MS) is a removable flash memory card format, launched by Sony in October 1998 and is also used in general to describe the whole family of Memory Sticks. This family includes the Memory Stick PRO, a revision that allows greater maximum storage capacity and faster file transfer speeds; Memory Stick Duo, a small-form-factor version of the Memory Stick (including the PRO Duo); and the even smaller Memory Stick Micro (M2). In December 2006 Sony added the Memory Stick PRO-HG, a high speed variant of the PRO, to be used for high definition still and video cameras.

Memory Stick PRO

The Memory Stick PRO, introduced in 2003 as a joint effort between Sony and SanDisk , would be the longer-lasting solution to the space problem. Most devices that use the original Memory Stick form factor support both the original Memory Sticks and the PRO Sticks; some readers that were not compatible could be upgraded to Memory Stick PRO support via a Flash ROM update. Memory Stick PROs have a marginally higher transfer speed and a maximum theoretical capacity of 32 GB. High Speed Memory Stick PROs are available, and newer devices support this High Speed mode, allowing for faster file transfers. All Memory Stick PROs larger than 1 GB support this High Speed mode, and High Speed Memory Stick Pros are backwards-compatible with devices that don't support the High Speed mode. High capacity memory sticks such as the 4 GB versions are expensive compared to other types of flash memory such as SD cards and CompactFlash

Memory Stick Duo and PRO Duo

The MagicGate standard for Memory Sticks is an encryption system allowing music to be downloaded to the card and played back by an authorized device, but not shared. Certain standard Memory Stick and all PRO sticks are MagicGate compatible.

The Memory Stick Duo is slightly smaller than the competing Secure Digital format and roughly two thirds the length of the standard form factor. It was developed in response to Sony's need for a smaller flash memory card for pocket-sized digital cameras and cell phones. Memory Stick Duos are available in all the same variants as their larger cousins: normal ones limited to 128 MB, higher capacity PRO Sticks (called Memory Stick PRO Duo in the Duo form factor), with and without High Speed mode, and with and without MagicGate support. There's also a simple adapter (often sold along with the Memory Stick Duo) which allows a Duo to be used in any device that can accept its larger cousins.

The normal and PRO versions of Memory Stick Duo are also used with the PSP, which when inserted into the Memory Stick Slot show saved game data, music, pictures and videos

Memory Stick Micro

In a joint venture with SanDisk, Sony released a new Memory Stick format on February 6, 2006. The Memory Stick Micro (M2) measures 15 × 12.5 × 1.2 mm—roughly one-quarter the size of the Duo, around the size of a fingernail—with 128MB, 256 MB, 512 MB, 1 GB, 2 GB and 4 GB capacities, with a theoretical limit of 32 GB. Maximum transfer speed is 160 Mbit/s. It comes with an adapter, much like the Duo Sticks, to ensure compatibility with current PRO devices.

Memory Stick PRO-HG

On December 11, 2006, Sony, together with SanDisk, announced a new version of Memory Stick. The Memory Stick PRO-HG evolved out of the PRO.

xD-Picture Card

The xD-Picture Card is a type of flash memory card, used mainly in digital cameras. xD originally stood for extreme Digital.[1] The cards were developed by Olympus and Fujifilm and introduced into the market in July 2002. Toshiba Corporation and Samsung Electronics manufacture the cards for Olympus and Fujifilm. xD cards are now sold under other brands, including Kodak, SanDisk, and Lexar.
xD cards are used in Olympus and Fujifilm digital cameras and Olympus digital voice recorders; Fujifilm also made an MP3 player that used the cards. As of 2006, xD cards are available in capacities of 16 MB, 32 MB, 64 MB, 128 MB, 256 MB, 512 MB, 1 GB, and 2 GB. xD cards have dimensions of 20 mm × 25 mm × 1.78 mm, and each weighs 2.8 grams

SDHC

A new SD format, SDHC (Secure Digital High Capacity, SD 2.0), allows capacities in excess of 2 GB. SDHC uses the FAT32 file system which supports a higher data density than FAT16[10]. It uses the same form factor as SD, but the SD 2.0 standard in SDHC uses a different memory addressing method (sector addressing vs byte addressing), thus theoretically reaching a maximum capacity of up to 2048GB. SDHC cards only work in SDHC compatible devices, but standard SD cards work in both SD and SDHC devices. The SDHC trademark is licensed to ensure compatibility.[11]

In August 2007 Toshiba announced that they would be launching a 32GB SDHC card and an 8 GB microSDHC card worldwide in January 2008. Toshiba also announced a 16GB version available in the last quarter of 2007.

A number of Key Features have been published for each:

1.SDHC Memory Card (High Speed Type) (1) Realizes maximum write speed of 6 MB per sec. (2) "Class 4” SD Speed Class, guaranteeing sustained data write at 4 MB/s. (3) Integrates highly secure CPRM copyright technology.

2. microSDHC Memory Card (1) Realizes large 8 GB capacity in a microSDHC Card. It can store 139 hours of music at a bit rate of 128kbit/s. (2) "Class 4” SD Speed Class, guaranteeing sustained data write at 4 MB/s. (3) Integrates highly secure CPRM copyright technology.

SDHC cards have SD Speed Class Ratings defined by the SD Association. The SD Speed Class Ratings specify the following minimum sustained write speed on to empty SDHC cards:

Class 2: 2 MB/s
Class 4: 4 MB/s
Class 6: 6 MB/s

As of April 2007, examples of devices which support the SDHC format include:

Photo / video
- Recent models of Canon PowerShot (aka Digital IXUS and IXY Digital),
Canon EOS, Casio Exilim, and Panasonic Lumix digital cameras
- The Nikon D40, D40x and Nikon D80, Pentax K100D, Pentax K110D (with
ROM Firmware ver. 1.01 and later) and the Pentax K10D digital SLRs as
well as ROM updates for other Pentax models
- Panasonic HDC-SD1 and SD5 camcorders
- The Kodak Z1275 will support the SDHC cards up to 8 GB.
- The Sanyo Xacti HDTV video camera
- The Ricoh Caplio R5 (with Firmware v1.6 or later) and Caplio R6.
Audio
- Cowon D2
- Creative Labs ZEN
- Edirol R-09 Solid State Digital Audio Recorder (Firmware 1.10)
- Sansa e200 series with Rockbox firmware (all non -R models) [12]
- Zoom H2
Readers
- SanDisk MicroMate compact USB SD adapter
- Kingston MobileLite 9 Multi Reader
- SanDisk Sansa View
- YE Data YD-8V08 internal floppy disk drive + 18-in-one internal USB
memory card reader/writer
- One Laptop Per Child XO laptops
Other devices
- The HTC Touch and TyTN II smartphones
- The Palm Treo 680
- The Nokia N800 Tablet
- The HTC P3600
- Several Garmin GPS devices such as the Zumo and Nuvi with the proper
software version.
- Nokia N95 mobile phone

Secure Digital card

Secure Digital (SD) is a flash (non-volatile) memory card format developed by Matsushita, SanDisk and Toshiba for use in portable devices, including digital cameras, handheld computers, PDAs and GPS units. As of 2006, SD card capacities include 8MB, 16MB, 32MB, 64MB, 128MB, 256MB, and 512MB, 1GB, 2 GB, 4 GB, 6 GB, 8 GB (4-32 GB: SDHC)[1] and 32GB.

The format has proven to be very popular. However, compatibility issues between older devices and the newer 2 GB and larger cards and the SDHC format have caused considerable confusion for consumers.

Form factor
SD cards are based on the older MultiMediaCard (MMC) format, but have a number of differences:

- The SD card is asymmetrically shaped so that it cannot be inserted upside down, whereas an MMC will go in most of the way but not make contact if inverted.

- Most SD cards are physically thicker than MMCs. SD cards generally measure 32 mm × 24 mm × 2.1 mm, but can be as thin as 1.4 mm, just like MMCs (see below).
The contacts are recessed beneath the surface of the card (like Memory Stick cards), protecting the contacts from contact with the fingers

- SD cards typically have higher data transfer rates, but this is always changing, particularly in light of recent improvements to the MMC standard.

- Digital rights management features are available but are seldom used.

Devices with SD slots can use the thinner MMCs, but the standard SD cards will not fit into the thinner MMC slots. SD cards can be used in CompactFlash or PC card slots with an adapter. miniSD and microSD cards can be used directly in SD slots with a physical interface adapter. There are some SD cards with a USB connector for dual-purpose use, and there are card readers which allow SD cards to be accessed via many connectivity ports such as USB, FireWire, and the common parallel port. SD cards can also be accessed via a floppy disk drive with a FlashPath adapter.

MultiMediaCard

The MultiMediaCard (MMC) is a flash memory memory card standard. Unveiled in 1997 by Siemens AG and SanDisk, it is based on Toshiba's NAND-based flash memory, and is therefore much smaller than earlier systems based on Intel NOR-based memory such as CompactFlash. MMC is about the size of a postage stamp: 24 mm x 32 mm x 1.4 mm. MMC originally used a 1-bit serial interface, but newer versions of the specification allow transfers of 4 or sometimes even 8 bits at a time. They have been more or less superseded by Secure Digital cards (SD card), but still see significant use because MMCs can be used in most devices which support SD cards and they are cheaper than SD cards [citation needed].

Typically, an MMC is used as storage media for a portable device, in a form that can easily be removed for access by a PC. For example, a digital camera would use an MMC for storing image files. With an MMC reader (typically a small box that connects via USB or some other serial connection, although some can be found integrated into the computer itself), a user could copy the pictures taken with the digital camera off to his or her computer. Modern computers, both laptops and desktops, often have SD slots, which can additionally read MMCs if the operating system drivers support them.

MMCs are currently available in sizes up to and including 4 GB with 8 GB models announced but not yet available. They are used in almost every context in which memory cards are used, like cellular phones, digital audio players, digital cameras and PDAs. Since the introduction of Secure Digital card and SDIO (Secure Digital Input/Output) slot few companies build MMC slots into their devices (an exception is some mobile devices like the Nokia 9300 communicator, where the smaller size of the MMC is a benefit), but the slightly thinner, pin-compatible MMCs can be used in almost any device that supports SD cards if the software/firmware on the devices support them.

Microdrives

Microdrives are tiny hard disks—about 25 mm (1") wide—packaged with a CompactFlash Type II form factor and interface. They were developed and released in 1999 by IBM in a 170 megabyte capacity. The division was then sold to Hitachi in December 2002 along with the Microdrive trademark. There are now other brands that sell Microdrives (such as Seagate, Sony, etc), and, over the years, these have become available in increasingly larger capacities (up to 8 GB as of August 2007).

While these drives fit into any CF II slot, they take more power on average (500 mA maximum) than flash memory (100 mA maximum) and so may not work in some low-power devices (for example, NEC HPCs). Being a mechanical device they are more sensitive to physical shock and temperature changes than flash memory.

The popular iPod mini and the Rio Carbon is a device which uses a compact Microdrive to store music.

CompactFlash

CompactFlash (CF) was originally developed as a type of data storage device used in portable electronic devices. For storage, CompactFlash typically uses flash memory in a standardized enclosure. This form was first specified and produced by SanDisk in 1994. The physical format is now used for a variety of devices

Description
There are two main subdivisions of CF cards, Type I (3.3 mm thick) and the thicker Type II (CF2) cards (5 mm thick). The CF Type II slot is used by Microdrives and some other devices. There are four main speeds of cards including the original CF, CF High Speed (using CF+/CF2.0), a faster CF 3.0 standard and a yet faster CF 4.0 standard that is being adopted as of 2007. The thickness of the CF card type is dictated by the preceding PCMCIA card type standard.

CF was among the first flash memory standards to compete with the earlier and larger PC card Type I memory cards, and was originally built around Intel's NOR-based flash memory, though it switched over to NAND. CF is among the oldest and most successful formats, and has held on to a niche in the professional camera market especially well. It has benefited from having both a good cost to memory size ratio relative to other formats for much of its life, and generally having larger capacities available than smaller formats.

CF cards can be used directly in PC Card slot with a plug adapter, used as an IDE hard drive with a passive adapter, and with a reader, to any number of common ports like USB or FireWire. As it has a bigger size relative to the smaller cards that came later, many other formats can be used directly in a CF card slot with an adapter (including SD/MMC, Memory Stick Duo, xD-Picture Card in a Type I slot, and SmartMedia in a Type II slot, as of 2005) (some multi-card readers use CF for I/O as well).

Flash memory, regardless of format, supports only a limited number of erase/write cycles before a particular "sector" can no longer be written. Memory specifications generally allow 10,000[1] to 1,000,000 write cycles. Typically the controller in a CompactFlash attempts to prevent premature wearout of a sector by mapping the writes to various other sectors in the card - a process referred to as wear levelling.

Type I and Type II
The only difference between the two types is that the Type II devices are 5mm thick while Type I devices are 3.3mm thick.[3] The vast majority of all Type II devices are Microdrives and other miniature hard drives. Flash based Type II devices are rare but a few examples do exist. [4][5] Even the largest capacity cards commonly available are Type I cards and most card readers will read both formats with the exception of some early CF based cameras where the slot is too small and some of the poorer quality USB card readers with the same problem.

Memory Card

A memory card or flash memory card is a solid-state electronic flash memory data storage device used with digital cameras, handheld and laptop computers, telephones, music players, video game consoles, and other electronics. They offer high re-record-ability, power-free storage, small form factor, and rugged environmental specifications. There are also non-solid state memory cards that do not use flash memory, and there are different types of flash memory. They are sometimes called "mem-cards" by gamers and/or techies.

Flash cards have been suggested as a possible replacement for the hard disk in Mp3 players, although USB flash memory drives, which work on almost any computer with a USB port, have been filling this role instead.

There are many different types of memory cards and jobs they are used for. Some common places include in digital cameras, in game consoles, in cell phones, and in industrial applications. PC card (PCMCIA) were among first commercial memory card formats (type I cards) to come out in the 1990s, but are now only mainly used in industrial applications and for I/O jobs (using types I/II/III), as a connection standard for devices (such as a modem). Also in 1990s, a number of memory card formats smaller than PC Card came out, including CompactFlash, SmartMedia, and Miniature Card. In other areas, tiny embedded memory cards (SID) were used in cell phones, game consoles started using proprietary memory card formats, and devices like PDAs and digital music players started using removable memory cards.

From the late 1990s into the early 2000s a host of new formats appeared, including SD/MMC, Memory Stick, xD-Picture Card, and a number of variants and smaller cards. The desire for ultra-small cards for cell-phones, PDAs, and compact digital cameras drove a trend toward smaller cards that left the previous generation of "compact" cards looking big. In digital cameras SmartMedia and CompactFlash had been very successful, in 2001 SM alone captured 50% of the digital camera market and CF had a strangle hold on professional digital cameras. By 2005 however, SD/MMC had nearly taken over SmartMedia's spot, though not to the same level and with stiff competition coming from Memory Stick variants, xD, as well as CompactFlash. In industrial fields, even the venerable PC card (PCMCIA) memory cards still manage to maintain a niche, while in cell-phones and PDAs, the memory card market is highly fragmented.

Nowadays, most new PCs have built-in slots for a variety of memory cards; Memory Stick, CompactFlash, SD, etc. Some digital gadgets support more than one memory card to ensure compatibility.

Image resolution

The resolution of a digital camera is often limited by the camera sensor (usually a charge-coupled device or CCD chip) that turns light into discrete signals, replacing the job of film in traditional photography. The sensor is made up of millions of "buckets" that collect charge in response to light. Generally, these buckets respond to only a narrow range of light wavelengths, due to a color filter over each. Each one of these buckets is called a pixel, and a demosaicing/interpolation algorithm is needed to turn the image with only one wavelength range per pixel into an RGB image where each pixel is three numbers to represent a complete color.

The one attribute most commonly compared on cameras is the pixel count. Due to the ever increasing sizes of sensors, the pixel count is into the millions, and using the SI prefix of mega- (which means 1 million) the pixel counts are given in megapixels. For example, an 8.0 megapixel camera has 8.0 million pixels.

The pixel count alone is commonly presumed to indicate the resolution of a camera, but this is a misconception. There are several other factors that impact a sensor's resolution. Some of these factors include sensor size, lens quality, and the organization of the pixels (for example, a monochrome camera without a Bayer filter mosaic has a higher resolution than a typical color camera). Many digital compact cameras are criticized for having too many pixels, in that the sensors can be so small that the resolution of the sensor is greater than the lens could possibly deliver.

Excessive pixels can even lead to a decrease in image quality. As each pixel sensor gets smaller it is catching fewer photons, and so the signal-to-noise ratio will decrease. This decrease leads to noisy pictures, poor shadow region quality and generally poorer-quality pictures.

Australian recommended retail price of Kodak digital camerasAs the technology has improved, costs have decreased dramatically. Measuring the "pixels per dollar" as a basic measure of value for a digital camera, there has been a continuous and steady increase in the number of pixels each dollar buys in a new camera consistent with the principles of Moore's Law. This predictability of camera prices was first presented in 1998 at the Australian PMA DIMA conference by Barry Hendy and since referred to as "Hendy's Law"

Sensor size and angle of view

Cameras with digital sensors that are smaller than the typical 35mm film size will have a smaller field or angle of view when used with a lens of the same focal length. This is because angle of view is a function of both focal length and the sensor or film size used.



If a sensor smaller than the full-frame 35mm film format is used, such as the use of APS-C-sized digital sensors in DSLRs, then the field of view is cropped by the sensor to smaller than the 35mm full-frame format's field of view. This narrowing of the field of view is often described in terms of a focal length multliplier or crop factor, a factor by which a longer focal length lens would be needed to get the same field of view on a full-frame camera.

If the digital sensor has approximately the same resolution (effective pixels per unit area) as the 35mm film surface (24 x 36 mm), then the result is similar to taking the image from the film camera and cutting it down (cropping) to the size of the sensor. For an APS-C size sensor, this would be a reduction to approximately the center 50% of the image. The cheaper, non-SLR models of digital cameras typically use much smaller sensor sizes and the reduction would be greater.

If the digital sensor has a higher or lower density of pixels per unit area than the film equivalent, then the amount of information captured will differ correspondingly. While resolution can be estimated in pixels per unit area, the comparison is complex since most types of digital sensor record only a single colour at each pixel location, and different types of film will have different effective resolutions. There are various trade-offs involved, since larger sensors are more expensive to manufacture and require larger lenses, while sensors with higher numbers of pixels per unit area are likely to suffer higher noise levels.

For these reasons, it is possible to obtain cheap digital cameras with sensor sizes much smaller than 35mm film, but with high pixel counts, that can still produce high-resolution images. Such cameras are usually supplied with lenses that would be classed as extremely wide angle on a 35mm camera, and which can also be smaller size and less expensive, since there is a smaller sensor to illuminate. For example, a camera with a 1/1.8" sensor has a 5.0x field of view crop, and so a hypothetical 5-50mm zoom lens will produce images that look similar (again the differences mentioned above are important) to those produced by a 35mm film camera with a 25–250mm lens, while being much more compact than such a lens for a 35mm camera since the imaging circle is much smaller.

This can be useful if extra telephoto reach is desired, as a certain lens on an APS sensor will produce an equivalent image to a significantly longer lens on a 35mm film camera shot at the same distance from the subject, the equivalent length of which depends on the camera's field of view crop. This is sometimes referred to as the focal length multiplier, but the focal length is a physical attribute of the lens and not the camera system itself. The downside to this is that wide angle photography is made somewhat more difficult, as the smaller sensor effectively and undesirably reduces the captured field of view. Some methods of compensating for this or otherwise producing much wider digital photographs involve using a fisheye lens and "defishing" the image in post processing to simulate a rectilinear wide angle lens.

Full-frame digital SLRs, that is, those with sensor size matching a frame of 35mm film, include Canon 1DS, 1DS II, and 5D, Kodak Pro DCS-14n, and Contax N Digital. There are very few digital cameras with sensors that can approach the resolution of larger-format film cameras, with the possible exception of the Mamiya ZD (22MP) and the Hasselblad H3D series of DSLRs (22 to 39 MP).

Common values for field of view crop in DSLRs include 1.3x for some Canon sensors, 1.5x for Sony APS-C sensors used by Nikon, Pentax and Konica Minolta and for Fujifilm sensors, 1.6 (APS-C) for most Canon sensors, ~1.7x for Sigma's Foveon sensors and 2x for Kodak and Panasonic 4/3" sensors currently used by Olympus and Panasonic. Crop factors for non-SLR consumer compact and bridge cameras are larger, frequently 4x or more.


From Wikipedia, the free encyclopedia

CMOS

Complementary metal–oxide–semiconductor (CMOS) ("see-moss", IPA: ['si.mɜs]), is a major class of integrated circuits. CMOS technology is used in chips such as microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for a wide variety of analog circuits such as image sensors, data converters, and highly integrated transceivers for many types of communication.

CMOS is also sometimes explained as complementary-symmetry metal–oxide–semiconductor. The words "complementary-symmetry" refer to the fact that the typical digital design style with CMOS uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions.

Two important characteristics of CMOS devices are high noise immunity and low static power supply drain. Significant power is only drawn when its transistors are switching between on and off states; consequently, CMOS devices do not produce as much heat as other forms of logic such as TTL (transistor-transistor logic). CMOS also allows a high density of logic functions on a chip.

CCD

A charge-coupled device (CCD) is an analog shift register, enabling analog signals (electric charges) to be transported through successive stages (capacitors) controlled by a clock signal. Charge coupled devices can be used as a form of memory or for delaying analog, sampled signals. Today, they are most widely used for serializing parallel analog signals, namely in arrays of photoelectric light sensors. This use is so predominant that in common parlance, "CCD" is (erroneously) used as a synonym for a type of image sensor even though, strictly speaking, "CCD" refers solely to the way that the image signal is read out from the chip.

The capacitor perspective is reflective of the history of the development of the CCD and also is indicative of its general mode of operation, with respect to readout, but attempts aimed at optimization of present CCD designs and structures tend towards consideration of the photodiode as the fundamental collecting unit of the CCD. Under the control of an external circuit, each capacitor can transfer its electric charge to one or other of its neighbours. CCDs are used in digital photography and astronomy (particularly in photometry, sensors, medical fluoroscopy, optical and UV spectroscopy and high speed techniques such as lucky imaging).

Digital color cameras generally use a Bayer mask over the CCD. Each square of four pixels has one filtered red, one blue, and two green (the human eye is more sensitive to green than either red or blue). The result of this is that luminance information is collected at every pixel, but the color resolution is lower than the luminance resolution. Better color separation can be reached by three-CCD devices (3CCD) and a dichroic beam splitter prism, that splits the image into red, green and blue components. Each of the three CCDs is arranged to respond to a particular color. Some semi-professional digital video camcorders (and most professionals) use this technique. Another advantage of 3CCD over a Bayer mask device is higher quantum efficiency (and therefore higher light sensitivity for a given aperture size). This is because in a 3CCD device most of the light entering the aperture is captured by a sensor, while a Bayer mask absorbs a high proportion (about 2/3) of the light falling on each CCD pixel. Since a very-high-resolution CCD chip is very expensive as of 2005, a 3CCD high-resolution still camera would be beyond the price range even of many professional photographers. There are some high-end still cameras that use a rotating color filter to achieve both color-fidelity and high-resolution. These multi-shot cameras are rare and can only photograph objects that are not moving. Bayer filter A

Bayer filter mosaic is a color filter array (CFA) for arranging RGB color filters on a square grid of photosensors. The term derives from the name of its inventor, Dr. Bryce E. Bayer of Eastman Kodak, and refers to a particular arrangement of color filters used in most single-chip digital image sensors used in digital cameras, camcorders, and scanners to create a color image. The filter pattern is 50% green, 25% red and 25% blue, hence is also called RGBG or GRGB

CCD Vs CMOS

Today, most digital still cameras use either a CCD images sensor or a CMOS sensor. Both types of sensor accomplish the same task of capturing light and converting it into electrical signals.

A CCD is an analog device. When light strikes the chip it is held as a small electrical charge in each photo sensor. The charges converted to voltage one pixel at a time as they are read from the chip. Additional circuitry in the camera converts the voltage into digital information.

A CMOS chip is a type of active pixel sensor made using the CMOS semiconductor process. Extra circuitry next to each photo sensor converts the light energy to a voltage. Additional circuitry on the chip converts the voltage to digital data.

Neither technology has a clear advantage in image quality. CMOS can potentially be implemented with fewer components, use less power and provide data faster than CCDs. CCD is a more mature technology and is in most respects the equal of CMOS.

Image sensor

An image sensor is a device that converts a visual image to an electric signal. It is used chiefly in digital cameras and other imaging devices. It is usually an array of charge-coupled devices (CCD) or CMOS sensors such as active-pixel sensors.

There are several main types of color image sensors, differing by the means of the color separation mechanism:

- Bayer sensor, low-cost and most common, using a Bayer filter that passes red, green, or blue light to selected pixels, forming interlaced grids sensitive to red, green, and blue. The image is then interpolated using a demosaicing algorithm.

- Foveon X3 sensor, using an array of layered sensors where every pixel contains three stacked sensors sensitive to the individual colors.

- 3CCD, using three discrete image sensors, with the color separation done by a dichroic prism. Considered the best quality, and generally more expensive than single-CCD sensors.

Megapixel

A megapixel is 1 million pixels, and is a term used not only for the number of pixels in an image, but also to express the number of sensor elements of digital cameras or the number of display elements of digital displays. For example, a camera with an array of 2048×1536 sensor elements is commonly said to have "3.1 megapixels" (2048 × 1536 = 3,145,728).

Digital cameras use photosensitive electronics, either charge-coupled device (CCD) or complementary metal–oxide–semiconductor (CMOS) image sensors, consisting of 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 having red, green, and blue regions in the Bayer filter arrangement, so that each sensor element can record the intensity of a single primary color of light. The camera interpolates the color information of neighboring sensor elements, through a process called demosaicing, to create the final image. These sensor elements are often called "pixels", even though they only record 1 channel (only red, or green, or blue) of the final color image. Thus, a so-called N-megapixel camera that produces an N-megapixel image provides only one-third of the information that an image of the same size could get from a scanner. Thus, certain color contrasts may look fuzzier than others, depending on the allocation of the primary colors (green has twice as many elements as red or blue in the Bayer arrangement).

In contrast to conventional image sensors, the Foveon X3 sensor uses three layers of sensor elements, so that it detects red, green, and blue intensity at each array location. This structure eliminates the need for de-mosaicing and eliminates the associated image artifacts, such as color blurring around sharp edges. Citing the precedent established by mosaic sensors, Foveon counts each single-color sensor element as a pixel, even though the native output file size has only one pixel per three camera pixels.[1] With this method of counting, an N-megapixel Foveon X3 sensor therefore captures the same amount of information as an N-megapixel Bayer-mosaic sensor, though it packs the information into fewer image pixels, without any interpolation.

Pixel

A pixel (short for picture element, using the common abbreviation "pix" for "picture") is a single point in a graphic image. Each such information element is not really a dot, nor a square, but an abstract sample. With care, pixels in an image can be reproduced at any size without the appearance of visible dots or squares; but in many contexts, they are reproduced as dots or squares and can be visibly distinct when not fine enough. The intensity of each pixel is variable; in color systems, each pixel has typically three or four dimensions of variability such as red, green, and blue, or cyan, magenta, yellow, and black

Technical
A pixel is generally thought of as the smallest complete sample of an image. The definition is highly context sensitive; for example, we can speak of printed pixels in a page, or pixels carried by electronic signals, or represented by digital values, or pixels on a display device, or pixels in a digital camera (photosensor elements). This list is not exhaustive, and depending on context there are several synonyms that are accurate in particular contexts, e.g. pel, sample, byte, bit, dot, spot, etc. We can also speak of pixels in the abstract, or as a unit of measure, in particular when using pixels as a measure of resolution, e.g. 2400 pixels per inch, 640 pixels per line, or spaced 10 pixels apart. The measures dots per inch (dpi) and pixels per inch (ppi) are sometimes used interchangeably, but have distinct meanings especially in the printer field, where dpi is a measure of the printer's resolution of dot printing (e.g. ink droplet density). For example, a high-quality inkjet image may be printed with 200 ppi on a 720 dpi printer. The more pixels used to represent an image, the closer the result can resemble the original. The number of pixels in an image is sometimes called the resolution, though resolution has a more specific definition. Pixel counts can be expressed as a single number, as in a "three-megapixel" digital camera, which has a nominal three million pixels, or as a pair of numbers, as in a "640 by 480 display", which has 640 pixels from side to side and 480 from top to bottom (as in a VGA display), and therefore has a total number of 640 × 480 = 307,200 pixels or 0.3 megapixels. The pixels, or color samples, that form a digitized image (such as a JPEG file used on a web page) may or may not be in one-to-one correspondence with screen pixels, depending on how a computer displays an image. In computing, an image composed of pixels is known as a bitmapped image or a raster image. The word raster originates from halftone printing technology, and has been widely used to describe television scanning patterns.

Basic Equipment In Digital Photography

Starting out in digital photography? Then you're right on track. In this article, you will learn about the basic tools that you need in order for you to start this enjoyable and challenging hobby - digital photography. Learning how to use a digital camera is not very hard, but you need to invest in time and practice before you can fully grasp how your digital camera works. Once you know how to operate each function in your digital camera, you are a step closer to taking quality photos.

Digital cameras used to cost a lot, but now there are many digital cameras in the market in all price ranges. However, you must remember that cameras that are not as expensive as other brands may not have a very good resolution, and some features may be missing. Higher priced cameras have enhanced features such as LCD monitoring, higher storage capacity and many others.

LCD monitoring is a very useful feature. With this enhancement, you will be able to preview the photo. This way you will be able to judge whether to take another picture until you are satisfied with the results.

It is also important to note the camera's resolution. High quality photos require high resolution cameras. Low resolution cameras do not produce photos in large sizes. At most, it can produce photos with 800 x 600 pixel resolution.

There are other gadgets that you will need in order to produce photos in larger quantity and higher quality. You need to get familiar with photo editing applications. This will greatly help in improving certain aspects of the photo that you were not able to achieve.

You will also be needing a printer. If you are a hobbyist, you may be able to purchase an inexpensive printer that will give you the quality that you need. However, if you plan on going into the photography business, you need to invest on a high quality printer. This sort of printer may be costly, but it will help you produce high quality photos. You will also need to invest on high quality photo paper.

There are other tools you may need such as tripods, lenses, lights, cases and memory cards. These items can be bought at very affordable prices.

Now once you get these tools in your checklist, you are well on your way to starting you new hobby or photography business!

By: Luke Cameron
Article Source: www.iSnare.com

Digital Photography

Digital photography, as opposed to film photography, uses electronic devices to record and capture the image as binary data. This facilitates storage and editing of the images on personal computers, and also the ability to show and delete unsuccessful images immediately on the camera or software itself.

Digital cameras now outsell film cameras and include features that are not found in film cameras such as the ability to shoot video and record audio. Some other devices, such as mobile phones, include digital photography features.

From Wikipedia, the free encyclopedia

The Early Digital Camera

A digital camera is basically a digital device that enables images to be captured. Digital camera images are stored electronically rather than on film. This process involves converting light into electrical charges, and then translating this back into the image that was seen through the digital camera LCD. Although the digital camera is a recent addition to the world of photography, the concept of the possibility of a digital camera was begun in the 1950s.

The early concept of the digital camera was closely linked to television technology. It began with digital images being recorded on scanners and in the form of digital video signals. In 1951 broadcasting companies were recording images as electrical impulses and onto magnetic tape from their television cameras, and this paved the way for digital camera technology to begin.

By 1956 electrical impulse recordings were common practise within film industry, and camera manufacturers began to dream of a digital camera device. The first record of a patent for a type of digital camera was in 1972 when Texas Instruments patented a camera that did not require film. However, the patent revealed a more analog based design rather than a digital camera, and there is no record of whether the camera was actually created. What the patent does show, however, is that interest towards a digital camera was growing with the idea that the need for film could be removed. A pioneer in the history of digital camera was Steve Sasson, an engineer at Kodak. Digital images were of the moon were being transmitted via satellite by NASA, using a mosaic photo sensor, and he saw the possibility of a digital camera for commercial use.

In 1972 he began to group together available equipment used within the film industry to create an image digitally rather than on film. Central to this early concept of the digital camera, and still used by digital cameras today, is the Charged Coupled Device. The CCD detects light and colour intensity and then converts this information into electrons. The value of each cell in the image is then read, and converted to binary format to make the image computer compatible. Steve Sasson produced his first digital camera image in 1979. The image took a total of 23 seconds to take, and a further 23 seconds to read from the playback unit.

Although the digital camera image was less than perfect, it showed that the digital camera was a possibility. Kodak had developed a camera that developed picture from light, but it was never manufactured for the public.

The first camera to be marketed was the Sony Mavica electronic still camera in 1981. It was not a true digital camera as the image was recorded on mini disc, and then attached to a television or video. It was more a freeze frame video camera but it greatly influenced people`s attitude to the recorded image. It made public the possibility of a camera that stored images using techniques other than film. It still used more television technology but was the first hand held with the general idea of digital camera usage. Cameras that could transmit images via satellite became popular, but were used by the media only due to the expense incurred. The possibilities were becoming apparent and images were used for news coverage. The first camera for general use with a computer was the Apple Quicktake 100 camera which appeared in1984.

In 1986 the Canon RC-701 was used for coverage of the Olympics, with quality images printed in the newspaper. This showed the possible quality, and the desire for the digital camera was born.

The first mega pixel sensor was invented in 1986. It contained 1.4 million pixels and was suitable for a digital camera image measuring 5x7 inches. In 1987 accessories for storing, printing, manipulating, transmitting, and recording digital images came onto the market, with the Fuji DS-P1 arriving in 1988. This is arguably the first true digital camera as recognised today, boasting a 16MB memory card. With the arrival of JPEG and MPEG standards in the 1990´s, the face of the digital camera was changed for ever. Kodak marketed the first readily available digital camera that met all standards, with the Kodak DC40 in 1995.

By: Roberto Sedycias
Article Source: http://www.superfeature.com

What is photography ?

Photography [fә'tɑgrәfi:],[foʊ'tɑgrәfi:] is the process of recording pictures by means of capturing light on a light-sensitive medium, such as a film or electronic sensor. Light patterns reflected or emitted from objects expose a sensitive silver halide based chemical or electronic medium during a timed exposure, usually through a photographic lens in a device known as a camera that also stores the resulting information chemically or electronically.

The word "photography" comes from the French photographie which is based on the Greek words φως phos ("light"), and γραφίς graphis ("stylus", "paintbrush") or γραφή graphê ("representation by means of lines" or "drawing"), together meaning "drawing with light." Traditionally, the product of photography has been called a photograph, commonly shortened to photo.

From Wikipedia, the free encyclopedia