The digital camera

Th e

digital camera is an impressive creation of the engineering art that contains mechanical, electronical and optical elements, microprocessors and software. This technology was derived from the utilitarian American technique, which, during the Cold War in 196 needed image sensors for the spying planes. At the !eginning the Americans wor"ed with analogical photos, which were transmitted !y planes on earth through radio waves. Then the images were digitali#ed and so the digital camera was created, and introduced at the middle of the 9 $s.

The digital camera photography

%ive years ago a digital camera was a "ind of toy. &o!ody dreamed to compare it with a serious camera. This attitude changed. 'f you spend !etween ( and 1( ), today, you can !uy a fantastic photographic device, one which in reality can offer a photographic quality that rises at the standards offered !y the !est refle* cameras. +ven the professional cameramen have !egun to use the digital cameras. There$s no dou!t that a high quality digital camera is more efficient, interesting and fle*i!le tool than an ordinary one, at least for a fan cameraman, computer e*pert. 1. Introduction notions ,ight capturing At a higher level, there are no !ig differences !etween a digital camera photo and an analogical one. The e*position in !oth cases means capturing and stoc"ing !right images. -nly this is achieved in different stoc"ing ways. %ilm, which can !e !lac" and white or colored, positive /slide0 or negative1 'mage sensor /CC2 or C3-40 and 5A3 memory1 All cameras capture light through a little tu!e called o!6ective. The light sensitive environment is !ehind the o!6ective.

%ilm or image sensor 'n an ordinary camera, the image is captured and stoc"ed on a film. 7ou can see the result when the film is developed. The developing is a pure chemical process /analogical also0. With a digital camera an image sensor captures the image, which is also an analogical unit. 8ut the digital camera transforms immediately the captured image in digital dates / and 10, which are stoc"ed in a 5am memory. The memory card is the !asis of the future evolutions a photo is su!dued to /for e*ample, the transfer on a computer or a printer0. While an ordinary film contains 9: or ;6 e*positions, cards can have different dimension types, and an almost unlimited capacity. And if a film can !e used only once, a card is used much more frequently. 't can !e "ept several years and can !e "ept for hundreds of thousands of e*positions. 2. The diaphragm We must measure the light quantity sent !y the o!6ective to find the film<sensor #one. The idea is to find the correct quantity of light so that the photo would !e neither overe*posed nor undere*posed. The traditional camera o!6ective is larger than the digital camera o!6ective. The o!6ective$s diaphragm The cheapest camera usually has an immo!ile diaphragm. the o!6ective can$t !e regulated. The sophisticated cameras still have a varia!le diaphragm that is the o!6ective opening device can modify its si#e, 6ust li"e our eye !all enlarges or diminishes in accordance with the light conditions. Altering the diaphragm si#e, one can regulate the light quantity that passes through the o!6ective. The larger the opening device, the more light will !e allowed in the sensi!le #one /film<sensor0. Clarity 'n the classical photography the fact that the medium o!6ective achieves clear photos is always underlined. 8efore ma"ing a photo one focuses the o!6ective at a certain distance. Clarity e*presses how much of your su!6ect #one will !e clear. =igh degree clarity is when the whole #one !eginning with the first plan and ending with the wanted su!6ect$s !ac"ground will !e clear. 7ou can manually ad6ust the clarity, or the camera will do it with the help of the Auto focus function. 3. The releasing speed The light quantity can !e ad6usted !y the diaphragm$s opening device and !y altering the e*position time. The tripping device The tripping device$s opening on a longer period of time allows a larger quantity of light to enter. An automatic camera will setup alone the time of e*position. The shortest time of releasing is 1<> second. The longest time can !e chosen !etween 1<>, 1<:, 1<9 and 1 second. The !etter the camera is, the more fle*i!le the releasing speed is. 4. The objective The o!6ective is a very important part of the camera. 't is a tu!e that leads the light inside the camera. The o!6ective is formed from glass or plastic lenses and can !e immo!ile or e*changea!le. The o!6ective has a larger focusing distance and different properties. The o!6ective lens The o!6ective can !e simple /with one lens0 or complicated, with more grouped lenses.

The refle* cameras use e*tremely !ig and heavy lenses. 8oth the o!6ective and the lenses of a digital camera are usually small, owing to the very small #one of the image sensor. A digital camera is almost a micro camera compared to a refle* camera. An o!6ective is characteri#ed !y 9 parameters. The !rightness The length /the focus distance, measured in millimeters0 The !rightness is given !y the diaphragm$s opening an o!6ective can o!tain. The focus distance and the sight The focus distance /the length0 of an o!6ective is measured in millimeters and represents the distance from the optical center of the lenses to the film<sensor. 3ost of the modern cameras are equipped with #oom lenses /a "ind of varia!le telescope0. The sight is the changing element. The digital camera o!6ective Changing the focus distance of the o!6ective, you can change the angle and so you can o!tain a wide?angle or telescopic effect. A ;@ #oom o!6ective can enlarge the su!6ect ; times from the largest to the smallest angle. We$ll discuss a!out the digital #oom term. The standard "ind of a #oom is the optical one, where the camera lenses enlarge the image. The digital #oom is a pseudo?function, indicated !y the producers, !ut useless in most cases. Through the digital #oom, the photo is artificially enlarged. This interpolation can !e reali#ed in any program of image processing. 8ales for auto focusing 4ome digital cameras can achieve photos in dar"ness or in half?dar"ness, !eing equipped with an auto focus illuminator. This is a small source of light that starts automatically in situations in which the focusing function hasn$t got enough light. THE DI IT!" #!$E%! &T%'#T'%E =ow does the camera wor"A A digital camera has very many things in common with a traditional camera. 'f we loo" how light enters in the camera we find. A lens system including some mechanical elements so the lenses can !e ad6usted to o!tain the focusing and #oom1 A diaphragm and a releasing system1 A measuring instrument for the light and a system for calculating the e*position settings. All these information are found in !oth camera types. The lenses gather and focus the light, so that the image is clear on the sensi!ility camera sensor. The diaphragm and the releaser ad6ust the light quantity that depends on the camera sensi!ility. What is special at a digital cameraA

The image sensor replaces the film1 The camera has a ,C2 screen, with several functions1 A software and data processing are strongly involved in the achieving of the photo1 The photos are digitally stoc"ed and can !e immediately evaluated and processed.

Together these : circumstances ma"e the comparison !etween a digital camera and an analogical camera impossi!le. They are completely different products. Without film, !ut with a high resolution 'n the case of a traditional camera, the light is gathered in a film that is "ept at dar"ness and later developed. 'n the case of a digital camera, the BdevelopingC ta"es place electronically and digitally inside the camera ? and in a second or less. The light is gathered in the image sensor, where it$s transformed in digital data and stoc"ed in the 5A3. The central unit of a digital camera is the image sensor, an electronic chip sensitive to light. The resolution is one of the parameters used to esta!lish the achieving price of a digital camera. The more mega pi*els it has, the more e*pensive it is. The term resolution is used for the num!er of BpointsC in an image. The more points an image has, the higher resolution it has, and the image is clearer. When we spea" a!out the digital images, the BpointsC are called pi*els. &o(t)are and computeri*ed image An image sensor isn$t a passive stoc"ing medium li"e a film. The sensor gathers the image data, !ut this data is immediately sent in the system and processed in the camera computer. The image data gathered in the sensors is primitive1 it$ll have to pass through a comple* process of finishing !efore !ecoming a color photo. The camera computer has an impressive num!er of charges. 't ta"es care of a lot of functions the image data has to pass through to o!tain a photo. The image$s colors are artificially recreated with the help of the camera software. That$s why the image quality is different from camera to camera. The "#D screen Almost all the digital cameras have an ,C2 screen. 't is found !ehind the main !ody. This screen has several functions. An ,C2 screen is e*cellent, something you get used to very fast and you are very pleased of. 't can !e used for. Disuali#ing and selecting the su!6ect /the searching function0 Camera$s setup Disuali#ing the captured image +rasing < editing images. An ,C2 screen uses almost all the camera !attery energy, !ut it$s the only negative thing you can say a!out it. ,uc"ily when you want to save the !attery, the screen can !e turned off and turned !ac" on !y pressing a specific !utton.

#hoosing a subject The most important function of the screen is the viewfinder. When the screen is turned on, it visuali#es the su!6ect in front of the o!6ective continuously, and this is the function used to select a su!6ect. The screen has, normally, a ;?: centimeters diagonal and enough space for almost 19 . pi*els. Therefore it is a miniaturi#ed edition of the photo and we see it on the screen. The vie)(inder An analogical camera has only a viewfinder. 't is a small hole, in which you can loo" and that shows you the su!6ect that will !e pictured. The viewfinder of the digital camera wor"s e*actly the same, !ut it is neither precise, nor useful. 't is used only when the sunrays are too intense to use the ,C2 display. The ,C2 display of performant cameras can !e switched in every direction, which ma"es ta"ing pictures in different positions much easier. A digital camera has a lot of ad6ustment options1 that is why the ,C2 display is used to navigate throughout the menu, where a num!er of settings and parameters can !e selected. The typical /most common0 settings are. 5esolution /16 @19 , 1 9:@E6>, etc.0 The type of image /coloured, grayscale0 The compression /#ero, small, medium, high0 The sensi!ility /1 '4-, 9 '4-0 A lot of cameras have e*tra, even more technical selection options, which are also controlled !y the aid of the menu. The image sensor The image sensor is Bthe filmC of the digital camera F and what an e*cellent film it isG The sensi!ility to the light can actually !e !igger than the sensi!ility of an ordinary film. That is why the image sensors are so widely used in astronomy, in the structure of the satellites etc. There are two types of sensors, !oth used in the digital cameras. CC2 C3-4 These two types of sensors have different structures. The CC2 sensor is still the most used type of image sensor. 't offers a good image quality, !ut its production is e*pensive. The CC2 also uses much energy, !ut it is considered an advanced technology and used in most digital cameras. The C3-4 sensor is a completely different type of sensor, sensitive to light, which is not at all technically advanced. The advantage of the C3-4 is that it requires less electronically components than the CC2, and, as a result, it is cheaper to reali#e. The C3-4 technology will radically simplify the construction of the digital camera and it is only a matter of time until it is adopted. +ven if the sensor of the camera is C3-4 or CC2, it has millions of tiny BeyesC used to capture a small quantity of light. The image sensor is somehow li"e a chess ta!le with small cells. +very cell is a photodiode /light sensitive electronic device0. When a sensor cell is sensitive to light, it reacts !y producing an electrical charge F an electrical tension. The tension charges the cells /li"e a condenser0 in the moment of the e*posure and it is relieved into an electron a few moments after the e*posion. This small charge is changed into a pi*el. This way, every image sensor contri!utes !y a pi*el to the final image. 4o an image sensor is an electronically device which contains millions of sensor cells fi*ed into a matri*. -ne point of an image is made !y the quantity of light that falls onto a specific photo?sensitive sensor cell. An image is first composed !y a gigantic model of tiny electric charges. This Belectrical dataC must !e transformed into !ytes / and 10 so that the digital image may !e formed. The transition from tension to digital !ytes ta"es place in the Analogical F 2igital Converter. The Converter captures the electrical pulses and translates them separately into num!ers. +ach num!er shows how much light has fallen onto one of the cells of the image sensor. / H!lac", : 9(Hwhite0.

Inainte de colorare

2upJ colorare

The more sensitive to the recording of the light differences a camera is, the more details you can o!tain in an image. The conversion procedure is called BsamplingC. After the conversion, the camera receives the data that will !e processed. The image sensor cannot distinguish the different colours of the light1 it 6ust records the quantity. %alse colours with coloured filter arrays ? C%A =ow can you o!tain a coloured image from one composed in grayscaleA 't is artificially reali#ed in most of the cameras F !y the aid of a colour filter fi*ed a!ove the image sensor. +very single cell is equipped with a colour filter. 'n practice, a coloured layer is applied a!ove the photodiode /with a photolithographic process0. The filter allows only the light /photons0 with a specific wavelength F same colour F to get to the photodiode. The photons that have different wavelengths are a!sor!ed !y the filter and do not arrive at the cells. This networ" of tiny coloured filters is called the C%A /coloured filter array0. The use of every shade of colour is not necessary in a C%A. 't is proved that the three !asical colours are more than enough. Ksually the 5L8 /red, green, !lue0 system is used. The complete image is made from these three !asical colours. The interpolation of the coloures and the post?processing The image sensor captures a mosaic of coloured dots /with one of the three !asical colours0. 8ut the colours from the real life are com!inations of the three. The authentic colours must, then, !e reconstructed. This reconstruction, also called composition, ta"es place in the computer of the camera. 't is equipped with software created to compare the data of every cell with the data of the neigh!or cells. This way the camera tries to guess the real colour of the pi*els. After the interpolation, the colours are remade, !ut in a pretty primitive version. %or a good colour image to !e o!tained, the data of the image must !e digitally processed. The software analyses every image pi*els and !alances the colours and the saturation using some e*act algorhytms. This type of processing is e*tremely important for the colours of the final image. They say it represents ( M of the quality of the image. The image sensors are electronic devices that are produced e*actly li"e the ones of a NC processor or 5A3 memory. 8ut, unli"e other computer chips, their dimension has an importance a!ove the consume power.

,nainte de restaurare

Dup+ restaurare

Price and dimension The individual chips are produced in the so?called capsules. They are !ig, round slices of 4i. that are placed in the superior side of every layer and that contain hundreds of chips that are eventually separated one from another. The !igger the individual surface of the sensor chip, the fewer chips are to !e e*tracted from the capsule. 4o maintaining a low dimension can maintain a low price F the !igger an image sensor, the more e*pensive it$s production. The tiny sensors are placed in the BcommonC digital cameras and are an advanced enhancement of the cameras$ sensors. Completely different and much !igger sensors are used in the professional cameras. The !igger the sensor is, the !igger is the quality. The image sensors are passing through ma6or developments. The new models o!tain a !igger resolution without increasing the total dimension of the sensor, while the other qualities /dynamics, etc.0 are "ept and even improved. The releasing speed A digital camera must !e capa!le to ad6ust the e*posure time. The photodiodes must have a proper quantity of light. 'n the traditional camera there is this mechanical o!turator that allows the passing of the light only for the necessary amount of time. 'n digital cameras, the image sensor is e*posed constantly to light and it is permanently charged. When we reali#e an e*posure, we choose the image data from one of the snapshots of the camera. At some professional cameras there is also a mechanical unleasher.

+*emplu de prelucrare a imaginii Inlocuirea fundalului The stoc-piling o( the image data 'mmediately after a digital camera has finished the processing of the image data, the image is saved as a specific image file into a memory card /5A30. 'nternal 5A3 The image sensor collects a precise dosage of light, which charges the individual sensor cells with electricity. The electric charge is transferred from the sensor cells through an amplifier to the A2 Converter, which transforms the electrical tension into !ytes. This e*tremely primitive !itmap that contains unprocessed image pi*els is transferred to the internal 5A3 of the camera. All digital cameras have a !uilt?in 5A3 !uffer, used for the temporary store of the image data. The !uffer is a part of the internal 5A3, which can have from a few mega!ytes to 19> 38. An internal 5A3 has a different meaning then the 5A3 where we store the images /the 5A3 card0. An internal 5A3 wor"s e*actly the same as the 5A3 memory of a NC. The internal !uffer stores the image data while they are processed !y the microprocessors of the digital camera. When the processing of the data is finished, the image is transferred to the e*iting device, which is either the ,C2 or the 5A3 card. The 5A3 card A digital camera is similar to a computer, and li"e any computer, it must store the data in a memory !an". While the computer uses the hard dis", most of the cameras are using a 5A3 card, which is a stoc"ing medium for the image files /and for any "ind of data0 that can !e filled and emptied, having a capacity that can reach 1L8, and can !e of various types. Compact %lash /C%0 F the most used, fle*i!le, cheap, !ig capacity 4mart 3edia F pretty used, small card, without a date and low standard 3emory 4tic" F limited distri!ution, pretty e*pensive, low speed 33C<3ultimedia F limited distri!ution, low speed, pretty e*pensive 4ecure 2igital ? limited distri!ution, low speed, pretty e*pensive

@2?Nicture F new type, it will replace 4mart 3edia

The inter(ace )ith the computer The most important methods of transferring the data to a NC are. A. 2irect ca!le connection 8. 2oc"ing station C. A card reader