Digital camera in the context of Camera

An image sensor or imager is a device that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, camera phones, optical mouse devices, medical imaging equipment, night vision equipment such as thermal imaging devices, radar, sonar, and others. As technology changes, electronic and digital imaging tends to replace chemical and analog imaging.

The two main types of electronic image sensors are the charge-coupled device (CCD) and the active-pixel sensor (CMOS sensor). Both CCD and CMOS sensors are based on metal–oxide–semiconductor (MOS) technology, with CCDs based on MOS capacitors and CMOS sensors based on MOSFET (MOS field-effect transistor) amplifiers. Analog sensors for invisible radiation tend to involve vacuum tubes of various kinds, while digital sensors include flat-panel detectors.

A camera phone is a mobile phone that is able to capture photographs and often record video using one or more built-in digital cameras. It can also send the resulting image wirelessly and conveniently. The first commercial phone with a color camera was the Kyocera Visual Phone VP-210, released in Japan in May 1999. While cameras in mobile phones used to be supplementary, they have been a major selling point of mobile phones since the 2010s.

Most camera phones are smaller and simpler than the separate digital cameras. In the smartphone era, the steady sales increase of camera phones caused point-and-shoot camera sales to peak about 2010, and decline thereafter. The concurrent improvement of smartphone camera technology and its other multifunctional benefits have led to it gradually replacing compact point-and-shoot cameras.

Digital imaging or digital image acquisition is the creation of a digital representation of the visual characteristics of an object, such as a physical scene or the interior structure of an object. The term is often assumed to imply or include the processing, compression, storage, printing and display of such images. A key advantage of a digital image, versus an analog image such as a film photograph, is the ability to digitally propagate copies of the original subject indefinitely without any loss of image quality.

Digital imaging can be classified by the type of electromagnetic radiation or other waves whose variable attenuation, as they pass through or reflect off objects, conveys the information that constitutes the image. In all classes of digital imaging, the information is converted by image sensors into digital signals that are processed by a computer and made output as a visible-light image. For example, the medium of visible light allows digital photography (including digital videography) with various kinds of digital cameras (including digital video cameras). X-rays allow digital X-ray imaging (digital radiography, fluoroscopy, and CT), and gamma rays allow digital gamma ray imaging (digital scintigraphy, SPECT, and PET). Sound allows ultrasonography (such as medical ultrasonography) and sonar, and radio waves allow radar. Digital imaging lends itself well to image analysis by software, as well as to image editing (including image manipulation).

An active-pixel sensor (APS) is an image sensor where each pixel sensor unit cell has a photodetector (typically a pinned photodiode) and one or more active transistors. In a metal–oxide–semiconductor (MOS) active-pixel sensor, MOS field-effect transistors (MOSFETs) are used as amplifiers. There are different types of APS, including the early NMOS APS and the now much more common complementary MOS (CMOS) APS, also known as the CMOS sensor. CMOS sensors are used in digital camera technologies such as cell phone cameras, web cameras, most modern digital pocket cameras, most digital single-lens reflex cameras (DSLRs), mirrorless interchangeable-lens cameras (MILCs), and lensless imaging for, e.g., blood cells.

CMOS sensors emerged as an alternative to charge-coupled device (CCD) image sensors and eventually outsold them by the mid-2000s.

JPEG (/ˈdʒeɪpɛɡ/ JAY-peg, short for Joint Photographic Experts Group and sometimes retroactively referred to as JPEG 1) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable trade off between storage size and image quality. JPEG typically achieves 10:1 compression with noticeable, but widely agreed to be acceptable perceptible loss in image quality. Since its introduction in 1992, JPEG has been the most widely used image compression standard in the world, and the most widely used digital image format, with several billion JPEG images produced every day as of 2015.

The Joint Photographic Experts Group created the standard in 1992, based on the discrete cosine transform (DCT) algorithm. JPEG was largely responsible for the proliferation of digital images and digital photos across the Internet and later social media. JPEG compression is used in a number of image file formats. JPEG/Exif is the most common image format used by digital cameras and other photographic image capture devices; along with JPEG/JFIF, it is the most common format for storing and transmitting photographic images on the World Wide Web. These format variations are often not distinguished and are simply called JPEG.

A sight or sighting device is any device used to assist in precise visual alignment (i.e. aiming) of weapons, surveying instruments, aircraft equipment, optical illumination equipment or larger optical instruments with the intended target. Sights can be a simple set or system of physical markers that serve as visual references for directly aligning the user's line of sight with the target (such as iron sights on firearms), or optical instruments that provide an optically enhanced—often magnified—target image aligned in the same focus with an aiming point (e.g. telescopic, reflector and holographic sights). There are also sights that actively project an illuminated point of aim (a.k.a. "hot spot") onto the target itself so it can be observed by anyone with a direct view, such as laser sights and infrared illuminators on some night vision devices, as well as augmented or even virtual reality-enabled digital cameras ("smart scopes") with software algorithms that produce digitally enhanced target images.

Ghost hunting is the process of investigating locations that are purportedly haunted by ghosts. The practice has been heavily criticized for its dismissal of the scientific method. No scientific study has confirmed the existence of ghosts. Ghost hunting is considered a pseudoscience by the vast majority of educators, academics, science writers and skeptics. Science historian Brian Regal described ghost hunting as "an unorganized exercise in futility".

Typically, a ghost-hunting team will attempt to collect "evidence" supporting the existence of paranormal activity. Ghost hunters also refer to themselves as paranormal investigators. Ghost hunters use a variety of electronic devices, including EMF meters, digital thermometers, both handheld and static digital video cameras, including thermographic and night vision cameras, night vision goggles, and digital audio recorders. Other more traditional techniques are also used, such as conducting interviews and researching the history of allegedly haunted sites. Dowsing and Ouija boards are other traditional techniques.

A point-and-shoot camera, also known as a compact camera and sometimes abbreviated to P&S, is a still camera (either film or digital) 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. They are popular for vernacular photography by people who do not consider themselves photographers but want easy-to-use cameras for snapshots of vacations, parties, reunions and other events.

Most compact digital cameras use small 1/2.3-type (“1/2.3-inch”) image sensors, but since 2008, a few non-interchangeable lens compact cameras use a larger sensor such as 1.0-type (“1-inch”), APS-C (e.g. Fujifilm X100 series), or even full frame (e.g. Sony RX1 series). Most models prioritize being operated in auto mode, but some high end point-and-shoot cameras have PASM (program, aperture priority, shutter priority, and manual modes) on the mode dial, raw image format, and a hot shoe. None have interchangeable lenses, but some have secondary lens mounts.

Consumer electronics, also known as home electronics, are electronic devices intended for everyday household use. Consumer electronics include those used for entertainment, communications, and recreation. Historically, these products were referred to as "black goods" in American English due to many products being housed in black or dark casings. This term is used to distinguish them from "white goods", which are meant for housekeeping tasks, such as washing machines and refrigerators. In British English, they are often called "brown goods" by producers and sellers. Since the 2010s, this distinction has been absent in big box consumer electronics stores, whose inventories include entertainment, communication, and home office devices, as well as home appliances.

Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver. Later products included telephones, televisions, calculators, cameras, video game consoles, mobile phones, personal computers, and MP3 players. In the 2010s, consumer electronics stores often sold GPS, automotive electronics (vehicle audio), video game consoles, electronic musical instruments (e.g., synthesizer keyboards), karaoke machines, digital cameras, and video players (VCRs in the 1980s and 1990s, followed by DVD players and Blu-ray players). Stores also sold smart light fixtures, network devices, camcorders, and smartphones. Some of the modern products being sold include virtual reality goggles, smart home devices that connect to the Internet, streaming devices, and wearable technology.

A handheld projector (also known as a pocket projector, mobile projector, pico projector or mini beamer) is an image projector in a handheld device. It was developed as a computer display device for compact portable devices such as mobile phones, personal digital assistants, and digital cameras, which have sufficient storage capacity to handle presentation materials but are too small to accommodate a display screen that an audience can see easily. Handheld projectors involve miniaturized hardware, and software that can project digital images onto a nearby viewing surface.

The system comprises five main parts: the battery, the electronics, the laser or LED light sources, the combiner optic, and in some cases, scanning micromirror devices. First, the electronics system turns the image into an electronic signal. Next, the electronic signals drive laser or LED light sources with different colors and intensities down different paths. In the combiner optic, the different light paths are combined into one path, defining a palette of colors. An important design characteristic of a handheld projector is the ability to project a clear image on various viewing surfaces.

In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as from fingers touching a touchscreen, sound entering a microphone, or light entering a digital camera, into a digital signal.

An ADC may also provide an isolated measurement such as an electronic device that converts an analog input voltage or current to a digital number representing the magnitude of the voltage or current. Typically the digital output is a two's complement binary number that is proportional to the input, but there are other possibilities.

A mode dial or camera dial is a dial used on digital cameras to change the camera's mode. Most digital cameras, including dSLR and mirrorless cameras, support modes, selectable either by a rotary dial or from a menu. On point-and-shoot cameras which support modes a range of scene types is offered. On dSLR and mirrorless cameras, mode dials usually offer access to manual settings. The more compact point-and-shoot cameras, and cameras offering a great many modes, do not have mode dials, using menus instead. Some interchangeable lenses themselves offer control over things such as aperture, reducing the need for mode support in the camera body.

An articulating screen is a built-in small electronic visual display which is not fixed, but rather can be repositioned using a hinge or pivot. The articulating screen is known under different other names such as flip-out screen, flip screen, adjustable screen, articulated screen, or hinged screen. According to the way it moves, there are five main types:

1. The display moves around one axis, so that it only tilts. It is called tilting screen or tiltable screen.
2. The display tilts horizontally both up and down and also vertically. This type is called double-hinged tilting screen, two-axis tilting screen, three-direction tilting screen or screen with 3-way tilt.
3. The display moves around two axes which are at a right angle to each other, so that the screen both tilts and swivels. This type is called swivel screen. Other names for this type are vari-angle screen, fully articulated screen, fully articulating screen, rotating screen, multi-angle screen, variable angle screen, flip-out-and-twist screen, twist-and-tilt screen and swing-and-tilt screen.
4. The display is mounted on a fully-articulating hinge that itself is attached to a tilting plate. Such display can be extended out from the back of the camera, ensuring it stays clear of the camera's left-mounted ports when flipping it out to the side. This type of articulating screen is called tilt-and-articulating screen.
5. The display moves into a variety of angles; it tilts horizontally and vertically and also rotates to a certain extent while staying aligned with the lens axis. It still can not be turned all the way up, down or to the side to be seen from the front of the camera for self-portraits. This type of articulating screen is called cross-tilt screen, flexible-tilt screen or flex-tilt screen.

Articulating screens are used in a variety of electronic devices such as laptops, camcorders, digital cameras, desk phones, mobile phones, DVD players and others; also TV screens and computer monitors can be articulating screens.

Image stitching or photo stitching is the process of combining multiple photographic images with overlapping fields of view to produce a segmented panorama or high-resolution image. Commonly performed through the use of computer software, most approaches to image stitching require nearly exact overlaps between images and identical exposures to produce seamless results, although some stitching algorithms actually benefit from differently exposed images by doing high-dynamic-range imaging in regions of overlap. Some digital cameras can stitch their photos internally.