Numeric photography

The numeric photography recovers the whole of the techniques allowing obtaining a Photographie via the use of a electronic sensor like surfaces photosensitive, as well as the techniques of treatment and diffusion which result from this. One opposes it to the silver Photographie.

History of numeric photography

  • the first Mavica (Video Magnetic Camera) of Sony appears in 1981. It is equipped with a sensor CCC with: 279300 pixels (Amstrad D950 which arrives at the same time on the market has 10 times of them less) and analogically stores the photographs on a minidiskette of a capacity of 50 photographs. With additional accessories, it is possible to visualize the photographs on a television set, to print them or send them by the phone network, without possibility of final improvement.
  • In 1990, Kodak leaves several apparatuses of professional use. Fotoman (1992) of Logitech, bound for the general public, makes it possible to store on 1 Mo, thirty-two photographs in levels of gray.
  • In 1994, appears at Apple Computer the first camera general public color, the QuickTake 100 of 0,3 Million pixels, like Fotoman Plus Logitech left time little afterwards.
  • In 1995, appears at Casio the first camera equipped with a back LCD bound for the general public.
  • In 1999, the sensors of more than mégapixel spread.
  • In 2002, it is sold in France more digital devices than the silver ones.
  • In 2003, Canon leaves the numerical first Reflex bound for the general public: EOS 300D or Rebel.
  • In 2004 of the numerical sensors equip a good number of mobile phones, generally with a definition of 640×400 pixels, sometimes with a sensor of 1,3 million pixels or more.
  • In 2006, the American giant Kodak as well as the whole of its competitors (Fuji, Agfa, KonicaMinolta…) know falls of sales turnovers records due to nonthe profitability of the silver apparatuses and accessories.
  • In 2007, Kodak creates a new type of sensor which, instead of testing in each point the luminosity of 3 colors, separates information from brightness and chrominance, and thus uses 4 sensors. The awaited benefit of it is a greater stability of brightness.

Numerical catch of sight

Capture

The systems Optical S (objective, reflector view finder, room reflex camera), of these apparatuses are close to the silver solutions, except for the Obturateur which is not necessary. An electronics component sensitive to the Light, the sensor, takes the place of the film and translated luminous information into electric signals . The image is translated into a matrix of value of brightness, the Digital image which will be, after treatment, stored in an electronic device of memory, generally a chart Mémoire flash of small size. The small size of the sensors gives to the objectives digital devices one depth of field higher than a silver apparatus than identical framing.

According to the apparatus and adjustments, the points (Pixel S) of the image are treated so as to improve returned: interpolation to reconstitute the colors, filtering to decrease the signal Report/ratio on noise, Stressing to increase the clearness, correction of the colors (Balance of the white), etc

Then, their number can be reduced to take less place, by decreasing the definition where the central zone is extended by interpolation to obtain a numerical effect of Zoom. To note that in this case, the additional pixels are interpolated, which involves a deterioration of the total quality of the image. The same treatment can be carried out a posteriori by a software of final improvement of image.

The sensor is a CCC, CMOS or a sensor FOVEON.

Transfer and storage

This resulting information is grouped in a data-processing file. Two big families of files are met:
  • the files JPEG are compressed files . The electronics of the apparatus applies the algorithm compression according to the selected rate. This compression is destructive, of information are lost. But the phenomenon remains not very perceptible for the human eye, for low levels of compression.
  • the files RAW are files “owners” (whose definition is not published), specific to each manufacturer containing all the information collected after treatment but before any compression. They are much larger than files JPEG. They require a software specialized to be exploited.

Lastly, in addition to the image itself, these files transport information on the conditions of catches of sight (heading Exif), which can be read completely or partially by many software. This heading can disappear during the treatment of final improvement if this format is not supported by the software used.

The photographs are stored either in the memory of the apparatus itself (in general, about some images of maximum resolution), or on an extractable memory card.

The transfer of the data can be made by a cable (USB in general), by extraction and reading of the memory card on a computer. Certain apparatuses can transfer the images by a system without wire (Bluetooth or WiFi).

The transfer can be made towards:

  • a personal Computer, allowing to visualize, sort and to treat the images;
  • a autonomous Hard drive portable;
  • a Printing where the possibilities of selection and final improvements are tiny;
  • a console of development on paper, also allowing to visualize and sort the images.
  • a portable reader Multimedia (Mobile phone, readers of files .mp3, readers of files poratbles, portable game console…)

The numerical cameras embarked on the mobile phones allow uses directed towards the communication. The images can thus be transferred towards the preceding equipment but also directly towards:

  • a site of Division of photographs or a Blog
  • the mobile of a correspondent by ms

Use

The produced images can be visualized on the back screen of the camera and removed with the need or exported towards a Ordinateur, improved thanks to software, published on Internet, printed, stored on Cédérom or DVD… Certaines printers, with or without control screen, read the chart-memories directly and do not require an intermediate computer. The old stage of development of film is removed, which saves time and sometimes also makes it possible to take photographs whose contents are very personal. But also, the pulling of the images color becomes about as easy as the pullings black paper and white which could be done with a laboratory amateur. However, special inks and papers are very expensive and the pulling of quality in residence is not competitive with professional pulling.

The models recent (2005) of cameras numerical, of compact types or reflex camera, propose sufficient resolution S (4 to 10 million Pixel S or more) to draw from the images of format A3, even higher, which authorizes the use of a numerical case for the illustration. The photojournalists use from now on numerical cameras electronically to transmit the photographs to their drafting since the place of catch of sight.

In parallel, the professional market uses also numerical Dos S of 11 (for Kodak) to 16 even 50 million pixels; all these sensors are designed to be placed at the back of the camera (from where their name of numerical back ). They are used in the fashion, on average formats (see photographic Format of film) or on photographic rooms (standard SINAR, GRETAG…) for the publicity or the reproduction of works of Article.

Popularity

The amateurs also accommodate with enthusiasm the digital devices whose cost clearly decreased. Home computing, the World Wide Web, the Email and the facility to divide its photographs with its close relations contributed probably much to this passion. Freedom to let each member of its family manage with her own way the photographs which it wishes and the number of their pullings had certainly his importance also. The user does not require more to consume films to even draw the documents if it is satisfied with the screen of the computer: he is completely autonomous. The numerical one makes it possible moreover to perform more tests with lower costs.

The current market

The current market of the numerical cameras is segmented in four principal categories:

  • a market in full rise, numerical cameras of the cellphones.

  • the digital reflexes (DSLR for “DIGITAL Single Lens Reflex” in English or “digital reflexes with only one objective” in opposition to the apparatuses “reflex camera” with two objectives, of type Rolleiflex), which comprise at the same time professional aircraft which are generally equipped with a sensor CCC of the same size that a sensor 24 X 36 (“full frame” in English), and aircraft more “prosumers” equipped with sensor a little smaller than 24 X 36. The size of the sensor generates a framing different from the image, similar to the change of eyepiece of a telescope. It results a factor from it from enlargement (cropping Factor in English) to apply to the focal distances of the objectives to have a framing are equivalent to the 24x36. This factor generally lies between 1 (full frame) and 1,6.

  • the compact ones, apparatuses general public, whose principal interest is compactness.

  • the bridges, thus named because they make the “bridge”, in term of marketing, between the two preceding classes, are apparatuses to which the apparance is close to the reflex cameras, but which generally do not have interchangeable optics.

In the last two segments, the direct vision of the image to be photographed on a back screen LCD makes it possible to be freed from the problem of the parallel sight. This characteristic starts to appear in the top-of-the-range reflex cameras.

The size of the sensors of these digital devices does not increase, it is their resolution of many pixels, and thus in “precision”, which increases: 1 million pixels in 2000,12 million pixels in 2007. On the marketing plan, the resolution is a sales point very much used, wrongly, because a too significant number of pixels on a small sensor does not involve an improvement of the quality of image, but on the contrary the faster appearance of " noise numérique".

Current disadvantages of the digital devices

  • the apparatuses are still extremely greedy in energy (especially the use of the bill-poster LCD). The ideal is to be able to use rechargeable batteries metal-hydride of the trade, without Ratchet effect thus without loss of capacity in time, contrary to the accumulators iron-nickel. The last digital devices are delivered with batteries to the Lithium of capacity definitely higher than those quoted previously, without ratchet effect. A refill makes it possible to take between 200 and 650 photographs according to the capacity of the pile and the use or not of the built-in flash.
  • a disadvantage which starts to be reduced on the new apparatuses: the shift between the support on the release and the catch of sight, very significant when a silver apparatus a long time was used; the mobile subjects are often except framework on the stereotype.
  • travels from There, it is necessary to be able to frequently reload the batteries and to envisage an important storage capacity for the images because it is not possible any more to buy a film in the local shop… 1 Go of memory (or more) and a charger for the car are a good precaution. One finds also fuel discharging machines of files which comprise an hard drive of 20,30,40 Go with or without posting (see Epson, Jobo, etc). One can obviously have a laptop for storage.
  • the apparatuses with interchangeable objective are very sensitive to the problem of dust, the more so as the effect of bellows produced by the ring of zoom aspires the particles inside, which then come to settle on the sensor. The solutions or the approaches are varied according to the marks:
    • Pentax place in front of the sensor a screen which one can clean. The problem is only pushed back at the time when a dust will come to be intercalated between the screen and the sensor.
    • Nikon and Kodak gives indications on the methods of cleaning of the sensor. New D300 has an active sytème of netoyage and D3 of a passive system.
    • Canon proposes in the menu a cleaning of sensor which exposes this one for a cleaning by air. Certain apparatuses (like the EOS 400D and EOS 1D Mark III) offer a self-cleaning sensor.
    • Olympus integrates into its E1 a vibrator with ultrasounds making fall dust on one… adhesive tape.
    • Presque all the marks suggest arranging the objective apparatus to the bottom (in order to support the fall of dust far from the sensor), to reasonably change the objective only in one clean atmosphere (to avoid the sandstorms!), etc
    • the vulnerability of the sensors to dust is a complex problem for two primary reasons. The small size of the pixels supports their screening, the latter is easily visible on the photographs. Very fine dust, more difficult to control, is also most prone to adherence by effect of Surface stress.
  • Certain apparatuses with aiming digital reflex whose size of the sensitive sensor is lower than 24×36 mm, see the recadrée photograph of approximately 10% - 20%. The consequences are a higher focal distance from approximately 60% (160 mm real for an objective 100 mm), which decreases the effect of great angle. This " inconvénient" , solved with the sensor Full Frame 24*36 can be an advantage during the use of a teleobjective. Thus one 200 mm becomes one 320 mm and a constant zoom 70-200 2.8 one 112/320 2.8, almost impossible to realize at the optical level.
  • the apparatuses general public far from are still made chromatic and of the definition of a silver apparatus 24x36, whose photograph contains the equivalent of 10 Go of data, that only a sensor of at least 55 million pixels is able to provide.
  • a numerical camera does not produce a photograph. The immaterialisation of the photographs poses a problem in the conservation: the digital photographs are preserved on numerical support, recognized like not very reliable on the long run. However, this limitation is counterbalanced by the facility to duplicate the images on various memory supports.

For submission to the beginners

Today, of many people having little experiment in photography find themselves in possession of compact numerical and can be impressed by a little mysterious expressions which they discover then. The explanations try to raise the veil of these mysteries.

Correction of exposure

This expression is sometimes replaced by compensation of exposure or compensation EV .

The exposure of the numerical sensor (or film on a classical device) is the quantity of light which it receives. This one grows with the exposure time and the diaphragm aperture. On an evolved/moved apparatus, the photographer chooses these two parameters while an automatic apparatus chooses them without operator action.

A traditional automatic provided with a traditional film gives acceptable results in good number of circumstances. Numerically (as on the slides), the range of the exposures which make pass the sensor of the black to the white is weaker. Under these conditions, one more frequently obtains from the zones under and/or over-exposed and the apparatus chooses an average position without knowing if it will satisfy the photographer.

Thus, the beginner can photograph flowers whose corollas, which present pretty nuances in nature, will uniformly become white on the photograph. The explanation lies in the fact that the exposure was ordered by the majority dark bottom on which were detached the clear flowers: the bottom was reasonably cleared up with the detriment of the subject and, to obtain a more satisfactory photograph, it would have been necessary to order with the apparatus to reduce the exposure. The case reverses arises when one photographs on snow a subject which becomes excessively dark.

It is the role of the correction which exists on compact numerical but not on compact traditional. Practically, it is in general defined by numbers varying per third between -2 (to under-expose) and +2 (to over-expose). These numbers are interpreted in terms of diaphragm apertures but it is that, on compact numerical, the very weak focal distance prohibits the openings as small as on a 24×36, under penalty of aberrations. The adjustment of the exposure is thus done by the exposure time: -1 corresponds to a division by 2 of this one, +2 with a multiplication by 4.

Balance white

A white body is a body which reflects all the lights, all the colors. It thus appears white in white light and red in red light. The problem becomes complicated when it is noted as a white body can appear white as well under an incandescent lighting as under a gray sky. Indeed, the physicists ensure that the first lighting produced a reddish light while the second produces a bluish light. It is the brain which interprets, up to a certain point, the colors seen by the eyes. It becomes complicated even more when this interpretation does not function any more opposite a photograph of the scene considered. Thus, one can be more or less shocked by a photograph of interior with dominant a red or a photograph of outside with dominant blue. In silver photography, this problem is solved by using films adapted to such or such type of lighting. Numerically, the calculator is satisfied to modify some values, which is a method much more flexible. Thus, the photographer generally has access to the adjustments Incandescent, Luminescent, Flash, Sun, Ombre, Nuages,… Two other positions are available. The Auto position tries to imitate the adjustment carried out by the brain, seems it successfully in many cases. On the other hand, measured the Blanc position is convenient for lightings out of the commun run (one often quotes the case of a part lit at the same time by bulbs and tubes). In this case, it is enough to aim at a blank paper located under lighting and to start to obtain the good adjustment.

Numerical famous brands of cameras

See specialized article: Industry of numeric photography

Related subjects with the numerical catch of sight

Impression of a numeric photography

The Digital image becomes a Photographie with the common direction of the term when it takes the form of a permanent test on Papier. The passage of the file image from the apparatus Digital photograph or from the scanner (and worked again or not on Computer) to this final test is done via a Imprimante. A chain being worth only what its weakest link is worth, the development of the digital photograph was slowed down a long time by the poor performances (high cost, poor quality of the produced images) of these peripherals. This problem was fortunately regulated since, and one now finds models accessible, able to reach famous “photo quality”. There exist today two great types of printers used for the digital photograph: those known as with thermal sublimation and those with jet of ink. The purchase price of the printer and the maximum resolution of the images which it provides constitute obviously of the important selection criteria, but the quality ratio/price of each model also depends on the cost on consumable, in particular of the cartridges of Encre black or color, which it requires. To note moreover that, if the ink jet printers of ink can function with plain paper, they do not give their full measurement only with paper says “photo quality”, which is not really cheap, even if the increase in consumption draws the prices downwards.

Side professionals, the Pictrography is one of the first processes of impression making it possible to obtain an image similar to silver pullings. There remains still used today in certain studios because its returned is quite higher than the impressions by jet of ink which cannot reproduce the totality of the spectrum Rouge blue green (RVB), which can limit itself technically only to CMJN (see also: Gamut).

The best currently returned at the point remains the treatment of the digital image on silver paper.

The film digitalization

When a numerical camera is not used, one can practice numeric photography all the same. Several ways are offered to the amateur and the professional.

This very widespread approach before the numerical cameras are available with current quality rests on the digitalization of a taken of traditional silver sight either on the level of film (negative or slide) or of the image on paper (see further, “the scan of reproduction”.

One uses then a scanner with high-resolution (of: 2000 dpi with: 5400 dpi for the scanners amateurs, much more for the professional scanners.) which analyzes the negative one directly or the slide and provides an digital image. Certain film scanners are provided with devices able to correct the defects of film automatically: dust, stripes. Indeed, being given the small size of the initial document (24×36 mm) the stripes and the dust stuck on film take often awkward proportions. The first users were obliged to make a manual cleaning in their software of final improvement of image. The most powerful scanners offer an automatic control of the presence of dust by a parallel analysis using a channel Infrarouge which is then used to apply an automatic filtering localized.

Advantages

  • a film scanner is generally less expensive than a numerical camera of the equivalent resolution (but that will undoubtedly change).
  • the price of a digital device can be expensive but it makes it possible to save many expenses of development.
  • the majority of the photo laboratories now propose the development of films with digitalization on a CD-ROM: It is thus less useful to have a scanner of film, always delicate and tiresome to use.

Disadvantages

  • the photographer does not benefit from the advantage of the numerical catch of sight (the immediate availability of the images).
  • the offer of film scanners is narrow and the market concentrates towards the professional models.

Some film scanners

Even if one meets some mixed scanners (scanners flat are able to read film 35 mm negative and slides - with a lower quality), they are generally specialized products.
  • Canon
  • Epson
  • Hewlett-Packard
    • PhotoSmart
    • S20
  • Kodak
  • Konica Minolta
    • DiMAGE Scan Multi Pro
    • DiMAGE Scan Elite 5400
    • DiMAGE Scan Dual IV
  • Nikon
    • Super CoolScan 5000ED
    • Super CoolScan 9000ED
    • Super CoolScan 4000ED (LS-4000)
    • Super CoolScan 8000ED (LS-8000)
    • CoolScan IV
    • CoolScan V ED
  • Olympus

The market always divides between scanners rather directed general public and turned scanners towards the needs for professionals (speed, very high-resolution, possibility of treating in quantity of the whole rollers of films, etc)

The scan of reproduction

This other approach is derived from the preceding one (film scan), but it is a question of digitizing of pullings paper. One thus uses a scanner of flat documents completely traditional. The photographer can simply ask for pullings paper of his film (or to use documents of any other origin) and with the possibility of working or of modifying these images.

Favors

  • Investment even weaker than for a film scanner.

Disadvantages

  • the stage of reproduction on paper degrades the quality of the image appreciably (compared to the image stored on silver film).
  • In the case of an image made on a numerical printer itself, one risks important effects of moire (such as one met some on the impressions woven before the development of the angles of screens in printing works). This effect can be reduced by certain software, but at the price of a reduction of quality (loss of definition).

See too

Related articles

External bonds

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