A digital camera (also digicam or camera for short) is a camera A camera is a device that records/stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images. The modern camera evolved from the camera obscura that takes video Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion or still photographs A photograph is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would see. The process and, or both, digitally A digital system is a data technology that uses discrete values. By contrast, non-digital (or analog) systems use a continuous range of values to represent information. Although digital representations are discrete, the information represented can be either discrete, such as numbers, letters or icons, or continuous, such as sounds, images, and by recording images A digital image is a representation of a two-dimensional image using ones and zeros . Depending on whether or not the image resolution is fixed, it may be of vector or raster type. Without qualifications, the term "digital image" usually refers to raster images also called bitmap images via an electronic Electronics is the branch of science and technology which makes use of the controlled motion of electrons through different media and vacuum. The ability to control electron flow is usually applied to information handling or device control. Electronics is distinct from electrical science and technology, which deals with the generation, image sensor An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices. Early sensors were video camera tubes but a modern one is typically a charge-coupled device or a complementary metal–oxide–semiconductor (CMOS) active-pixel sensor.

Many compact digital still cameras can record sound Sound recording and reproduction is an electrical or mechanical inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording. Acoustic analog recording is achieved by a small microphone diaphragm that and moving video Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion as well as still photographs A photograph is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would see. The process and. Most 21st century cameras are digital.^[1]

Digital cameras can do things film cameras cannot: displaying images on a screen immediately after they are recorded, storing thousands of images on a single small memory device, recording video with sound, and deleting images to free storage space. Some can crop pictures Cropping refers to the removal of the outer parts of an image to improve framing, accentuate subject matter or change aspect ratio. Depending on the application, this may be performed on a physical photograph, artwork or film footage, or achieved digitally using image editing software. The term is common to the film, broadcasting, photographic, and perform other elementary image editing Image editing encompasses the processes of altering images, whether they be digital photographs, traditional analog photographs, or illustrations. Traditional analog image editing is known as photo retouching, using tools such as an airbrush to modify photographs, or editing illustrations with any traditional art medium. Graphic software programs,. The optical system works the same as in film cameras Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts (bonded by gelatin) with variable crystal sizes that determine the sensitivity, contrast and resolution of the film. When the emulsion is sufficiently exposed to light (or other forms of electromagnetic radiation such as X-rays), it forms, typically using a lens with a variable diaphragm In optics, a diaphragm is a thin opaque structure with an opening at its centre. The role of the diaphragm is to stop the passage of light, except for the light passing through the aperture. Thus it is also called a stop (an aperture stop, if it limits the brightness of light reaching the focal plane, or a field stop or flare stop for other uses to focus light onto an image pickup device. The diaphragm and shutter admit the correct amount of light to the imager, just as with film but the image pickup device is electronic rather than chemical.

Digital cameras are incorporated into many devices ranging from PDAs The term PDA was first used on January 7, 1992, by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las Vegas, Nevada, referring to the Apple Newton. In 1996, Nokia introduced the first mobile phone with full PDA functionality, the 9000 Communicator, which has since grown to become the world's best-selling PDA and which spawned and mobile phones A mobile phone is an electronic device used for full duplex two-way radio telecommunications over a cellular network of base stations known as cell sites. Mobile phones differ from cordless telephones, which only offer telephone service within limited range through a single base station attached to a fixed land line, for example within a home or (called camera phones A camera phone is a mobile phone which is able to capture either still photographs or video. Since early in the 21st century the majority of cameras and of mobile phones in use are camera phones. Most camera phones are simpler than separate digital cameras. Their usual fixed focus lenses and smaller sensors limit their performance in poor lighting,) to vehicles. The Hubble Space Telescope The Hubble Space Telescope is a space telescope that was carried into orbit by a space shuttle in April 1990. It is named after the American astronomer Edwin Hubble. Although not the first space telescope, Hubble is one of the largest and most versatile, and is well-known as both a vital research tool and a public relations boon for astronomy. The and other astronomical Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe devices are essentially specialized digital cameras.

Types of digital cameras

Digital cameras are made in a wide range of sizes, prices and capabilities. The majority are camera phones A camera phone is a mobile phone which is able to capture either still photographs or video. Since early in the 21st century the majority of cameras and of mobile phones in use are camera phones. Most camera phones are simpler than separate digital cameras. Their usual fixed focus lenses and smaller sensors limit their performance in poor lighting,, operated as a mobile application through the cellphone menu. Professional photographers A photographer, from the Greek φωτός, "light" and γράφω, "I write", is a person who takes photographs using a camera. A professional photographer uses photography to earn money whilst amateur photographers take photographs for pleasure and to record an event, emotion, place, or person and many amateurs use larger, more expensive digital single-lens reflex cameras (DSLR) for their greater versatility. Between these extremes lie digital compact cameras and bridge digital cameras that "bridge" the gap between amateur and professional cameras. Specialized cameras including multispectral imaging equipment and astrographs continue to serve the scientific, military, medical and other special purposes for which digital photography Digital photography is a form of photography that uses digital technology to make images of subjects. Until the advent of such technology, photography used photographic film to create images which could be made visible by photographic processing. By contrast, digital photographs can be displayed, printed, stored, manipulated, transmitted, and was invented.

Compact digital cameras

Compact cameras are designed to be small and portable and are particularly suitable for casual and "snapshot" use, thus are also called point-and-shoot camera A point-and-shoot camera, also called a compact camera, is a still camera designed primarily for simple operation. Most use focus free lenses or autofocus for focusing, automatic systems for setting the exposure options, and have flash units built in. The smallest, generally less than 20 mm thick, are described as subcompacts or "ultra-compacts". Most, apart from ruggedized or water-resistant models, incorporate a retractable lens assembly allowing a thin camera to have a moderately long focal length and thus fully exploit an image sensor larger than that on a camera phone, and a mechanized lens cap to cover the lens when retracted.

Compact cameras are usually designed to be easy to use, sacrificing advanced features and picture quality for compactness and simplicity; images can usually only be stored using lossy compression A lossy compression method is one where compressing data and then decompressing it retrieves data that is different from the original, but is close enough to be useful in some way. Lossy compression is most commonly used to compress multimedia data , especially in applications such as streaming media and internet telephony. By contrast, lossless (JPEG In computing, JPEG is a commonly used method of lossy compression for photographic images. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality). Most have a built-in flash 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 usually of low power, sufficient for nearby subjects. Live preview is almost always used to frame the photo. They may have limited motion picture Film encompasses individual motion pictures, the field of film as an art form, and the motion picture industry. Films are produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects capability. Compacts often have macro Macro photography is close-up photography. The classical definition is that the image projected on the "film plane" is close to the same size as the subject.[citation needed] Lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances capability and zoom lenses A zoom lens is a mechanical assembly of lens elements with the ability to vary its focal length , as opposed to a fixed focal length (FFL) lens (see prime lens). They are commonly used with still, video, motion picture cameras, projectors, some binoculars, microscopes, telescopes, telescopic sights, and other optical instruments but the zoom range is usually less than for bridge and DSLR cameras. Generally a contrast-detect autofocus An Autofocus optical system uses a sensor, a control system and a motor to focus fully automatic or on a manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication system, using the image data from the live preview feed off the main imager, focuses the lens.

Typically, these cameras incorporate a nearly-silent leaf shutter into their lenses.

For lower cost and smaller size, these cameras typically use image sensors An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices. Early sensors were video camera tubes but a modern one is typically a charge-coupled device or a complementary metal–oxide–semiconductor (CMOS) active-pixel sensor with a diagonal of approximately 6 mm, corresponding to a crop factor In digital photography, a crop factor is related to the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. In the case of digital cameras, the imaging device would be a digital sensor. The most commonly used definition around 6. This gives them weaker low-light performance, greater depth of field In optics, particularly as it relates to film and photography, the depth of field is the portion of a scene that appears acceptably sharp in the image. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under, generally closer focusing ability, and smaller components than cameras using larger sensors.

Bridge cameras

Bridge are higher-end digital cameras that physically and ergonomically Ergonomics is the science of designing jobs, equipment and workplaces to fit workers. Proper ergonomic design is necessary to prevent repetitive strain injuries, which can develop over time and can lead to long-term disability resemble DSLRs A digital single-lens reflex camera is a digital camera that uses a mechanical mirror system and pentaprism to direct light from the lens to an optical viewfinder on the back of the camera and share with them some advanced features, but share with compacts the use of a fixed lens and a small sensor. Like compacts, most use live preview to frame the image. Autofocus An Autofocus optical system uses a sensor, a control system and a motor to focus fully automatic or on a manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication is achieved using the same contrast-detect mechanism, but many bridge cameras feature a manual focus mode, in some cases using a separate focus ring, for greater control.

Due to the combination of large physical size but a small sensor, many of these cameras have very highly specified lenses with large zoom range and fast aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at, partially compensating for the inability to change lenses. To compensate for the reduced sensitivity of their small sensors, these cameras almost always include an image stabilization Image stabilization is a family of techniques used to reduce blurring associated with the motion of a camera or its subject. Specifically, it compensates for pan and tilt (angular movement, equivalent to yaw and pitch) of a camera or other imaging device. It is used in image-stabilized binoculars, still and video cameras, and astronomical system to enable longer handheld exposures.

These cameras are sometimes marketed as and confused with digital SLR cameras since the appearance is similar. Bridge cameras lack the reflex viewing system of DSLRs, have so far been fitted with fixed (non-interchangeable) lenses (although in some cases accessory wide-angle or telephoto converters can be attached to the lens), and can usually take movies with sound. The scene is composed by viewing either the liquid crystal display or the electronic viewfinder (EVF). Most have a longer shutter lag In photography, shutter lag is the delay between triggering the shutter and when the photograph is actually recorded. This is a common problem in the photography of fast-moving objects or people in motion than a true dSLR, but they are capable of very good image quality (with sufficient light) while being more compact and lighter than DSLRs. High-end models of this type have comparable resolutions to low and mid-range DSLRs. Many of these cameras can store images in a Raw image format A camera raw image file contains minimally processed data from the image sensor of either a digital camera, image or motion picture film scanner. Raw files are so named because they are not yet processed and therefore are not ready to be used with a bitmap graphics editor or printed. Normally, the image is processed by a raw converter in a wide-, or processed and JPEG In computing, JPEG is a commonly used method of lossy compression for photographic images. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality compressed, or both (sometimes TIFF). The majority have a built-in flash similar to those found in DSLRs.

Digital single lens reflex cameras

Digital single-lens reflex cameras (DSLRs) are digital cameras based on film single-lens reflex cameras A single-lens reflex camera is a camera that typically uses a semi-automatic moving mirror system that permits the photographer to sometimes see exactly what will be captured by the film or digital imaging system, as opposed to pre-SLR cameras where the view through the viewfinder could be significantly different from what was captured on film. ( (SLRs). They take their name from their unique viewing system, in which a mirror reflects light from the lens through a separate optical viewfinder. In order to capture an image the mirror is flipped out of the way, allowing light to fall on the imager. Since no light reaches the imager during framing, autofocus is accomplished using specialized sensors in the mirror box itself. Most 21st century DSLRs also have a "live view" mode that emulates the live preview system of compact cameras, when selected.

These cameras have much larger sensors than the other types, typically 18 mm to 36 mm on the diagonal (crop factor In digital photography, a crop factor is related to the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. In the case of digital cameras, the imaging device would be a digital sensor. The most commonly used definition 2, 1.6, or 1). This gives them superior low-light performance, less depth of field In optics, particularly as it relates to film and photography, the depth of field is the portion of a scene that appears acceptably sharp in the image. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under at a given aperture, and a larger size.

They make use of interchangeable lenses; each major DSLR manufacturer also sells a line of lenses specifically intended to be used on their cameras. This allows the user to select a lens designed for the application at hand: wide-angle, telephoto, low-light, etc. So each lens does not require its own shutter, DSLRs use a focal-plane shutter in front of the imager, behind the mirror.

The mirror flipping out of the way at the moment of exposure makes a distinctive "clack" sound.

Mirrorless interchangeable lens camera

In late 2008 a new type of camera emerged, combining the larger sensors and interchangeable lenses of DSLRs with the live preview viewing system of compact cameras, either through an electronic viewfinder or on the rear LCD. These are simpler and more compact than DSLRs due to the removal of the mirror box, and typically emulate the handling and ergonomics of either DSLRs or compacts. As of 2009 the only such system is Micro Four Thirds, borrowing components from the Four Thirds DSLR system.

Digital rangefinders

A rangefinder is a user-operated optical mechanism to measure subject distance once widely used on film cameras. Most digital cameras measure subject distance automatically using acoustic or electronic techniques, but it is not customary to say that they have a rangefinder.

Line-scan camera systems

A line-scan camera is a camera device containing a line-scan image sensor An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices. Early sensors were video camera tubes but a modern one is typically a charge-coupled device or a complementary metal–oxide–semiconductor (CMOS) active-pixel sensor chip, and a focusing mechanism. These cameras are almost solely used in industrial settings to capture an image of a constant stream of moving material. Unlike video cameras, line-scan cameras use a single array of pixel sensors, instead of a matrix of them. Data coming from the line-scan camera has a frequency, where the camera scans a line, waits, and repeats. The data coming from the line-scan camera is commonly processed by a computer, to collect the one-dimensional line data and to create a two-dimensional image. The collected two-dimensional image data is then processed by image-processing methods for industrial purposes.

Line-scan technology is capable of capturing data extremely fast, and at very high image resolutions. Usually under these conditions, resulting collected image data can quickly exceed 100 MB in a fraction of a second. Line-scan-camera–based integrated systems, therefore are usually designed to streamline the camera's output in order to meet the system's objective, using computer technology which is also affordable.

Line-scan cameras intended for the parcel handling industry can integrate adaptive focusing mechanisms to scan six sides of any rectangular parcel in focus, regardless of angle, and size. The resulting 2-D captured images could contain, but are not limited to 1D and 2D barcodes, address information, and any pattern that can be processed via image processing methods. Since the images are 2-D, they are also human-readable A human-readable medium or human-readable format is a representation of data or information that can be naturally read by humans and can be viewable on a computer screen. Advanced integrated systems include video coding, optical character recognition Optical character recognition, usually abbreviated to OCR, is the mechanical or electronic translation of scanned images of handwritten, typewritten or printed text into machine-encoded text. It is widely used to convert books and documents into electronic files, to computerize a record-keeping system in an office, or to publish the text on a (OCR) and finish-line cameras for high speed sports.

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