A camera raw image file contains minimally processed data from the image sensor of either a digital camera, a motion picture film scanner, or other image scanner. Raw files are named so because they are not yet processed and therefore are not ready to be printed or edited with a bitmap graphics editor. Normally, the image is processed by a raw converter in a wide-gamut internal color space where precise adjustments can be made before conversion to a "positive" file format such as TIFF or JPEG for storage, printing, or further manipulation. There are dozens of raw formats in use by differen ...
ⓘ Digital photography
Digital photography uses cameras containing arrays of electronic photodetectors to capture images focused by a lens, as opposed to an exposure on photographic film. The captured images are digitized and stored as a computer file ready for further digital processing, viewing, electronic publishing, or digital printing.
Until the advent of such technology, photographs were made by exposing light sensitive photographic film and paper, which was processed in liquid chemical solutions to develop and stabilize the image. Digital photographs are typically created solely by computer-based photoelectric and mechanical techniques, without wet bath chemical processing.
The first consumer digital cameras were marketed in the late 1990s. Professionals gravitated to digital slowly, and were won over when their professional work required using digital files to fulfill the demands of employers and/or clients, for faster turn-around than conventional methods would allow. Starting around 2000, digital cameras were incorporated in cell phones and in the following years, cell phone cameras became widespread, particularly due to their connectivity to social media websites and email. Since 2010, the digital point-and-shoot and DSLR formats have also seen competition from the mirrorless digital camera format, which typically provides better image quality than the point-and-shoot or cell phone formats but comes in a smaller size and shape than the typical DSLR. Many mirrorless cameras accept interchangeable lenses and have advanced features through an electronic viewfinder, which replaces the through-the-lens finder image of the SLR format.
While digital photography has only relatively recently become mainstream, the late 20th century saw many small developments leading to its creation. The history of digital photography as we know it began in the 1950s. In 1951, the first digital signals were saved to magnetic tape via the first video tape recorder. Six years later, in 1957, the first digital image was produced through a computer by Russell Kirsch. It was an image of his son.
The metal-oxide-semiconductor MOS process, invented by engineers Mohamed Atalla and Dawon Kahng at Bell Labs in 1959, led to the development of digital semiconductor image sensors, including the charge-coupled device CCD and later the CMOS sensor. The first semiconductor image sensor was the CCD, invented by physicists Willard S. Boyle and George E. Smith at Bell Labs in 1969. While researching the MOS process, they realized that an electric charge was the analogy of the magnetic bubble and that it could be stored on a tiny MOS capacitor. As it was fairly straighforward to fabricate a series of MOS capacitors in a row, they connected a suitable voltage to them so that the charge could be stepped along from one to the next. The CCD is a semiconductor circuit that was later used in the first digital video cameras for television broadcasting, and its invention was recognized by a Nobel Prize in Physics in 2009.
The first image of Mars was taken as the Mariner 4 flew by it on July 15, 1965, with a camera system designed by NASA/JPL. Later, in 1976 the Mars Viking Lander produced digital images from the surface of Mars. While not what we usually define as a digital camera, it used a comparable process. It used a video camera tube, followed by a digitizer, rather than a mosaic of solid state sensor elements. This produced a digital image that was stored on tape for later slow transmission back to Earth.
The first published color digital photograph was produced in 1972 by Michael Francis Tompsett using CCD sensor technology and was featured on the cover of Electronics Magazine. It was a picture of his wife, Margaret Thompsett. The Cromemco Cyclops, a digital camera developed as a commercial product and interfaced to a microcomputer, was featured in the February 1975 issue of Popular Electronics magazine. It used metal-oxide semiconductor MOS technology for its image sensor.
An important development in digital image compression technology was the discrete cosine transform DCT, a lossy compression technique first proposed by Nasir Ahmed while he was working at the University of Texas in 1972. DCT compression later became the basis for JPEG image standard, which was introduced by the Joint Photographic Experts Group in 1992. JPEG compresses images down to much smaller file sizes, and has become the most widely used image file format. The JPEG standard was largely responsible for popularizing digital photography.
The first self-contained portable digital camera was created later in 1975 by Steven Sasson of Eastman Kodak. Sassons camera used CCD image sensor chips developed by Fairchild Semiconductor in 1973. The camera weighed 8 pounds 3.6 kg, recorded black and white images to a cassette tape, had a resolution of 0.01 megapixels 10.000 pixels, and took 23 seconds to capture its first image in December 1975. The prototype camera was a technical exercise, not intended for production. While it was not until 1981 that the first consumer camera was produced by Sony, Inc., the groundwork for digital imaging and photography had been laid.
The first digital single-lens reflex DSLR camera was the Nikon SVC prototype demonstrated in 1986, followed by the commercial Nikon QV-1000C released in 1988. The first widely commercially available digital camera was the 1990 Dycam Model 1; it also sold as the Logitech Fotoman. It used a CCD image sensor, stored pictures digitally, and connected directly to a computer for downloading images. Originally offered to professional photographers for a hefty price, by the mid-to-late 1990s, due to technology advancements, digital cameras were commonly available to the general public.
The advent of digital photography also gave way to cultural changes in the field of photography. Unlike with traditional photography, dark rooms and hazardous chemicals were no longer required for post-production of an image – images could now be processed and enhanced from behind a computer screen in ones own home. This allowed for photographers to be more creative with their processing and editing techniques. As the field became more popular, types of digital photography and photographers diversified. Digital photography took photography itself from a small somewhat elite circle, to one that encompassed many people.
The camera phone helped popularize digital photography, along with the Internet, social media, and the JPEG image format. The first cell phones with built-in digital cameras were produced in 2000 by Sharp and Samsung. Small, convenient, and easy to use, camera phones have made digital photography ubiquitous in the daily life of the general public.
1.1. History Number of photos taken
According to research from KeyPoint Intelligence/InfoTrends, an estimated 400 billion digital photos were taken globally in 2011 and this will rise to 1.2 trillion photos in 2017. Several billion JPEG images are produced every day as of 2015. An estimated 85 percent of the photos taken in 2017 will be done with the smartphone rather than a traditional digital camera.
2.1. Digital camera Sensors
Image sensors read the intensity of light, and digital memory devices store the digital image information as RGB color space or as raw data.
The two main types of sensors are charge-coupled devices CCD, in which the photocharge is shifted to a central charge-to-voltage converter, and CMOS or active pixel sensors.
2.2. Digital camera Multifunctionality and connectivity
Except for some linear array type of cameras at the highest-end and simple webcams at the lowest-end, a digital memory device usually a memory card; floppy disks and CD-RWs are less common is used for storing images, which may be transferred to a computer later.
Digital cameras can take pictures, and may also record sound and video. Some can be used as webcams, some can use the PictBridge standard to connect to a printer without using a computer, and some can display pictures directly on a television set. Similarly, many camcorders can take still photographs, and store them on videotape or on flash memory cards with the same functionality as digital cameras.
Digital photography is one of the most exceptional instances of the shift from converting conventional analog information to digital information. This shift is so tremendous because it was a chemical and mechanical process and became an all digital process with a built in computer in all digital cameras.
2.3. Digital camera Performance metrics
The quality of a digital image is a composite of various factors, many of which are similar to those of film cameras. Pixel count typically listed in megapixels, millions of pixels is only one of the major factors, though it is the most heavily marketed figure of merit. Digital camera manufacturers advertise this figure because consumers can use it to easily compare camera capabilities. It is not, however, the major factor in evaluating a digital camera for most applications. The processing system inside the camera that turns the raw data into a color-balanced and pleasing photograph is usually more critical, which is why some 4+ megapixel cameras perform better than higher-end cameras.
Resolution in pixels is not the only measure of image quality. A larger sensor with the same number of pixels generally produces a better image than a smaller one. One of the most important differences is an improvement in image noise. This is one of the advantages of digital SLR single-lens reflex cameras, which have larger sensors than simpler cameras so-called point and shoot cameras of the same resolution.
- Processing: digital and/or chemical processing of negative and print.
- Capture format: pixel count, digital file type, film format.
- Capture medium: CMOS, CCD, negative film, reversal film etc.
- Lens quality: resolution, distortion, dispersion see Lens optics)
2.4. Digital camera Pixel counts
The number of pixels n for a given maximum resolution w horizontal pixels by h vertical pixels is the product n = w × h. This yields e. g. 1.92 megapixels 1.920.000 pixels for an image of 1600 × 1200.
The pixel count quoted by manufacturers can be misleading as it may not be the number of full-color pixels. For cameras using single-chip image sensors the number claimed is the total number of single-color-sensitive photosensors, whether they have different locations in the plane, as with the Bayer sensor, or in stacks of three co-located photosensors as in the Foveon X3 sensor. However, the images have different numbers of RGB pixels: Bayer-sensor cameras produce as many RGB pixels as photosensors via demosaicing interpolation, while Foveon sensors produce uninterpolated image files with one-third as many RGB pixels as photosensors. Comparisons of megapixel ratings of these two types of sensors are sometimes a subject of dispute.
The relative increase in detail resulting from an increase in resolution is better compared by looking at the number of pixels across or down the picture, rather than the total number of pixels in the picture area. For example, a sensor of 2560 × 1600 sensor elements is described as "4 megapixels" 2560 × 1600= 4.096.000. Increasing to 3200 × 2048 increases the pixels in the picture to 6.553.600 6.5 megapixels, a factor of 1.6, but the pixels per cm in the picture at the same image size increases by only 1.25 times. A measure of the comparative increase in linear resolution is the square root of the increase in area resolution, i.e., megapixels in the entire image.
2.5. Digital camera Dynamic range
Practical imaging systems both digital and film, have a limited "dynamic range": the range of luminosity that can be reproduced accurately. Highlights of the subject that are too bright are rendered as white, with no detail; shadows that are too dark are rendered as black. The loss of detail in the highlights is not abrupt with film, or in dark shadows with digital sensors. "Highlight burn-out" of digital sensors, is not usually abrupt in output images due to the tone mapping required to fit their large dynamic range into the more limited dynamic range of the output be it SDR display or printing. Because sensor elements for different colours saturate in turn, there can be hue or saturation shift in burnt-out highlights.
Some digital cameras can show these blown highlights in the image review, allowing the photographer to re-shoot the picture with a modified exposure. Others compensate for the total contrast of a scene by selectively exposing darker pixels longer. A third technique is used by Fujifilm in its FinePix S3 Pro digital SLR. The image sensor contains additional photodiodes of lower sensitivity than the main ones; these retain detail in parts of the image too bright for the main sensor.
High-dynamic-range imaging HDR addresses this problem by increasing the dynamic range of images by either
- by using exposure bracketing and post-processing the separate images to create a single image with a higher dynamic range.
- increasing the dynamic range of the image sensor or
2.6. Digital camera Storage
Many camera phones and most digital cameras use memory cards having flash memory to store image data. The majority of cards for separate cameras are Secure Digital SD format; many are CompactFlash CF and the other formats are rare. XQD card format was the last new form of card, targeted at high-definition camcorders and high-resolution digital photo cameras. Most modern digital cameras also use internal memory for a limited capacity for pictures that can be transferred to or from the card or through the cameras connections; even without a memory card inserted into the camera.
Memory cards can hold vast numbers of photos, requiring attention only when the memory card is full. For most users, this means hundreds of quality photos stored on the same memory card. Images may be transferred to other media for archival or personal use. Cards with high speed and capacity are suited to video and burst mode capture several photographs in a quick succession.
Because photographers rely on the integrity of image files, it is important to take proper care of memory cards. Common advocacy calls for formatting of the cards after transferring the images onto a computer. However, since all cameras only do quick formatting of cards, it is advisable to carry out a more thorough formatting using appropriate software on a PC once in a while. Effectively, this involves scanning of the cards to search for possible errors.
3. Market impact
In late 2002, the cheapest digital cameras were available in the United States for around $100. At the same time, many discount stores with photo labs introduced a "digital front end", allowing consumers to obtain true chemical prints as opposed to ink-jet prints in an hour. These prices were similar to those of prints made from film negatives. However, because digital images have a different aspect ratio than 35 mm film images, people have started to realize that 4x6 inch prints crop some of the image off the print. Some photofinishers have started offering prints with the same aspect ratio as the digital cameras record.
In July 2003, digital cameras entered the disposable camera market with the release of the Ritz Dakota Digital, a 1.2-megapixel 1280 x 960 CMOS-based digital camera costing only $11 USD. Following the familiar single-use concept long in use with film cameras, Ritz intended the Dakota Digital for single use. When the pre-programmed 25-picture limit is reached, the camera is returned to the store, and the consumer receives back prints and a CD-ROM with their photos. The camera is then refurbished and resold.
Since the introduction of the Dakota Digital, a number of similar single-use digital cameras have appeared. Most single-use digital cameras are nearly identical to the original Dakota Digital in specifications and function, though a few include superior specifications and more advanced functions such as higher image resolutions and LCD screens. Most, if not all these single-use digital cameras cost less than $20 USD, not including processing. However, the huge demand for complex digital cameras at competitive prices has often caused manufacturing shortcuts, evidenced by a large increase in customer complaints over camera malfunctions, high parts prices, and short service life. Some digital cameras offer only a 90-day warranty.
Since 2003, digital cameras have outsold film cameras. Prices of 35mm compact cameras have dropped with manufacturers further outsourcing to countries such as China. Kodak announced in January 2004 that they would no longer sell Kodak-branded film cameras in the developed world. In January 2006, Nikon followed suit and announced they would stop production of all but two models of their film cameras. They will continue to produce the low-end Nikon FM10, and the high-end Nikon F6. In the same month, Konica Minolta announced it was pulling out of the camera business altogether. The price of 35mm and APS Advanced Photo System compact cameras have dropped, probably due to direct competition from digital and the resulting growth of the offer of second-hand film cameras. Pentax have reduced production of film cameras but not halted it. The technology has improved so rapidly that one of Kodaks film cameras was discontinued before it was awarded a "camera of the year" award later in the year. The decline in film camera sales has also led to a decline in purchases of film for such cameras. In November 2004, a German division of Agfa-Gevaert, AgfaPhoto, split off. Within six months it filed for bankruptcy. Konica Minolta Photo Imaging, Inc. ended production of Color film and paper worldwide by March 31, 2007. In addition, by 2005, Kodak employed less than a third of the employees it had twenty years earlier. It is not known if these job losses in the film industry have been offset in the digital image industry. Digital cameras have decimated the film photography industry through declining use of the expensive film rolls and development chemicals previously required to develop the photos. This has had a dramatic effect on companies such as Fuji, Kodak, and Agfa. Many stores that formerly offered photofinishing services or sold film no longer do, or have seen a tremendous decline. In 2012, Kodak filed for bankruptcy after struggling to adapt to the changing industry. See Photographic film.
In addition, digital photography has resulted in some positive market impacts as well. The increasing popularity of products such as digital photo frames and canvas prints is a direct result of the increasing popularity of digital photography.
Digital camera sales peaked in March 2012 averaging about 11 million units a month, but sales have declined significantly ever since. By March 2014, about 3 million were purchased each month, about 30 percent of the peak sales total. The decline may have bottomed out, with sales average hovering around 3 million a month. The main competitor is smartphones, most of which have built-in digital cameras, which routinely get better. Like most digital cameras, they also offer the ability to record videos. While smartphones continue to improve on a technical level, their form factor is not optimized for use as a camera and battery life is typically more limited compared to a digital camera.
3.1. Market impact Social impact
Digital photography has made photography available to a larger group of people. The new technology and editing programs available to photographers has changed the way photographs are presented to the public. There are photographs that are so heavily manipulated "photoshopped" that they end up looking nothing like the original photograph and this changes the way they are perceived. Until the advent of the digital camera, amateur photographers used either print or slide film for their cameras. Slides are developed and shown to an audience using a slide projector. Digital photography revolutionized the industry by eliminating the delay and cost. The ease of viewing, transferring, editing and distributing digital images allowed consumers to manage their digital photos with ordinary home computers rather than specialized equipment.
Camera phones, being the majority of cameras, have arguably the largest impact. The user can set their smartphones to upload their products to the Internet, preserving them even if the camera is destroyed or the images deleted. Some high street photography shops have self-service kiosks that allow images to be printed directly from smartphones via Bluetooth technology.
Archivists and historians have noticed the transitory nature of digital media. Unlike film and print, which are tangible and immediately accessible to a person, digital image storage is ever-changing, with old media and decoding software becoming obsolete or inaccessible by new technologies. Historians are concerned that we are creating a historical void where information and details about an era would have been lost within either failed or inaccessible digital media. They recommend that professional and amateur users develop strategies for digital preservation by migrating stored digital images from old technologies to new. Scrapbookers who may have used film for creating artistic and personal memoirs may need to modify their approach to digital photo books to personalize them and retain the special qualities of traditional photo albums.
The web has been a popular medium for storing and sharing photos ever since the first photograph was published on the web by Tim Berners-Lee in 1992 an image of the CERN house band Les Horribles Cernettes. Today photo sharing sites such as Flickr, Picasa, and PhotoBucket, as well as social Web sites, are used by millions of people to share their pictures. In todays world digital photography and social media websites allow organizations and corporations to make photographs more accessible to a greater and more diverse population. For example, National Geographic Magazine has a Twitter, Snapchat, Facebook, and Instagram accounts and each one includes content aimed for the type of audience that are part of each social media community. It is also important to remember that digital photography has also had an impact in other fields, such as medicine. It has allowed doctors to help diagnose diabetic retinopathy and it is used in hospitals to diagnose and treat other diseases.
3.2. Market impact Digitally altered imagery
New technology with digital cameras and computer editing affects the way we perceive photographic images today. The ability to create and fabricate realistic imagery digitally as opposed to untouched photos changes the audience’s perception of truth’ in digital photography Manipulation in the digital era allows us to brush up our pictures, shape our memories to be picture perfect and therefore shape our identities.
4. Recent research and innovation
Research and development continues to refine the lighting, optics, sensors, processing, storage, display, and software used in digital photography. Here are a few examples.
- In advanced camera or camcorders, manipulating the sensitivity of the sensor not one, but 2 or more neutral density filters are available.
- Advanced bokeh techniques use a hardware system of 2 sensors, one to take the photo as usual while the other records depth information. Bokeh effect and refocusing can then be applied to an image after the photo is taken.
- An objects specular reflection can be captured using computer-controlled lights and sensors. This is needed to create attractive images of oil paintings, for instance. It is not yet commercially available, but some museums are starting to use it.
- High-dynamic-range cameras and displays are commercially available. Sensors with dynamic range in excess of 1.000.000:1 are in development, and software is also available to combine multiple non-HDR images shot with different exposures into an HDR image.
- Motion blur can be dramatically removed by a flutter shutter a flickering shutter that adds a signature to the blur, which postprocessing recognizes. It is not yet commercially available.
- Panoramic photographs can be created directly in camera without the need for any external processing. Some cameras feature a 3D Panorama capability, combining shots taken with a single lens from different angles to create a sense of depth.
- 3D models can be created from collections of normal images. The resulting scene can be viewed from novel viewpoints, but creating the model is very computationally intensive. An example is Microsofts Photosynth, which provided some models of famous places as examples.
- Dust reduction systems help keep dust off of image sensors. Originally introduced only by a few cameras like Olympus DSLRs, have now become standard in most models and brands of detachable lens camera, except the low-end or cheap ones.
Other areas of progress include improved sensors, more powerful software, advanced camera processors, enlarged gamut displays, built in GPS and WiFi, and computer-controlled lighting.
5.1. Comparison with film photography Advantages already in consumer level cameras
The primary advantage of consumer-level digital cameras is the low recurring cost, as users need not purchase photographic film. Processing costs may be reduced or even eliminated. Digicams tend also to be easier to carry and to use, than comparable film cameras. They more easily adapt to modern use of pictures. Some, particularly those that are smartphones, can send their pictures directly to e-mail or web pages or other electronic distribution.
5.2. Comparison with film photography Advantages of professional digital cameras
- Faster workflow: Management colour and file, manipulation and printing tools are more versatile than conventional film processes. However, batch processing of RAW files can be time consuming, even on a fast computer.
- Immediate image review and deletion is possible; lighting and composition can be assessed immediately, which ultimately conserves storage space.
- Precision and reproducibility of processing: since processing in the digital domain is purely numerical, image processing using deterministic non-random algorithms is perfectly reproducible and eliminates variations common with photochemical processing that make many image processing techniques difficult if not impractical.
- Much faster ingest of images, it will take no more than a few seconds to transfer a high resolution RAW file from a memory card vs many minutes to scan film with a high quality scanner.
- High volume of images to medium ratio; allowing for extensive photography sessions without changing film rolls. To most users a single memory card is sufficient for the lifetime of the camera whereas film rolls are a re-incurring cost of film cameras.
- Digital manipulation: A digital image can be modified and manipulated much easier and faster than with traditional negative and print methods. The digital image to the right was captured in raw image format, processed and output in 3 different ways from the source RAW file, then merged and further processed for color saturation and other special effects to produce a more dramatic result than was originally captured with the RAW image.
Manufacturers such as Nikon and Canon have promoted the adoption of digital single-lens reflex cameras DSLRs by photojournalists. Images captured at 2+ megapixels are deemed of sufficient quality for small images in newspaper or magazine reproduction. Eight- to 24-megapixel images, found in modern digital SLRs, when combined with high-end lenses, can approximate the detail of film prints from 35 mm film based SLRs.
5.3. Comparison with film photography Disadvantages of digital cameras
- As with any sampled signal, the combination of regular periodic pixel structure of common electronic image sensors and regular periodic structure of typically man-made objects being photographed can cause objectionable aliasing artefacts, such as false colors when using cameras using a Bayer pattern sensor. Aliasing is also present in film, but typically manifests itself in less obvious ways such as increased granularity due to the stochastic grain structure stochastic sampling of film.
A large number of mechanical film camera existed, such as the Leica M2. These battery-less devices had advantages over digital devices in harsh or remote conditions.
5.4. Comparison with film photography Equivalent featuresImage noise and grain
Noise in a digital cameras image may sometimes be visually similar to film grain in a film camera.Speed of use
Turn of the century digital cameras had a long start-up delay compared to film cameras, i.e., the delay from when they are turned on until they are ready to take the first shot, but this is no longer the case for modern digital cameras with start-up times under 1/4 seconds.Frame rate
While some film cameras could reach up to 14 fps, like the Canon F-1 with rare high speed motor drive., professional digital SLR cameras can take still photographs at highest frame rates. While the Sony SLT technology allows rates of up to 12 fps, the Canon EOS-1Dx can take stills at a 14 fps rate. The Nikon F5 is limited to 36 continuous frames the length of the film without the cumbersome bulk film back, while the digital Nikon D5 is able to capture over 100 14-bit RAW images before its buffer must be cleared and the remaining space on the storage media can be used.Image longevity
Depending on the materials and how they are stored, analog photographic film and prints may fade as they age. Similarly, the media on which digital images are stored or printed can decay or become corrupt, leading to a loss of image integrity.Colour reproduction
Colour reproduction gamut is dependent on the type and quality of film or sensor used and the quality of the optical system and film processing. Different films and sensors have different color sensitivity; the photographer needs to understand his equipment, the light conditions, and the media used to ensure accurate colour reproduction. Many digital cameras offer RAW format sensor data, which makes it possible to choose color space in the development stage regardless of camera settings.
Even in RAW format, however, the sensor and the cameras dynamics can only capture colors within the gamut supported by the hardware. When that image is transferred for reproduction on any device, the widest achievable gamut is the gamut that the end device supports. For a monitor, it is the gamut of the display device. For a photographic print, it is the gamut of the device that prints the image on a specific type of paper. Color gamut or Color space is an area where points of color fit in a three-dimensional space.
Professional photographers often use specially designed and calibrated monitors that help them to reproduce color accurately and consistently.
5.5. Comparison with film photography Frame aspect ratios
Most digital point & shoot cameras have an aspect ratio of 1.33 4:3, the same as analog television or early movies. However, a 35 mm pictures aspect ratio is 1.5 3:2. Several digital cameras take photos in either ratio, and nearly all digital SLRs take pictures in a 3:2 ratio, as most can use lenses designed for 35 mm film. Some photo labs print photos on 4:3 ratio paper, as well as the existing 3:2. In 2005 Panasonic launched the first consumer camera with a native aspect ratio of 16:9, matching HDTV. This is similar to a 7:4 aspect ratio, which was a common size for APS film. Different aspect ratios is one of the reasons consumers have issues when cropping photos. An aspect ratio of 4:3 translates to a size of 4.5"x6.0". This loses half an inch when printing on the "standard" size of 4"x6", an aspect ratio of 3:2. Similar cropping occurs when printing on other sizes, i.e., 5"x7", 8"x10", or 11"x14".