digital cameraa camera that stores images digitally rather than recording them on film

7/21/2019 Digital CameraA Camera That Stores Images Digitally Rather Than Recording Them on Film

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DIGITAL CAMERA

Digital camera A camera that storesimagesdigitallyrather than recording them on film. Once a picturehas been taken, it can be downloadedto a computer system,and then manipulated with agraphicsprogramand printed. Unlike film photographs, which have an almost infinite resolution, digital photos are limited bythe amount ofmemoryin the camera, the optical resolution of thedigitizingmechanism, and, finally, by the

resolution of the finaloutput device. Even the best digital cameras connected to the bestprinterscannotproduce film-uality photos. !owever, if the final output device is alaser printer, it doesn"t really matterwhether you take a real photo and then scanit, or take a digital photo. #n both cases, the image musteventually be reduced to the resolution of the printer.

$he big advantage of digital cameras is that making photos is both ine%pensive and fast because there is nofilm processing. #nterestingly, one of the biggest boosters of digital photography is &odak, the largestproducer of film. &odak developed the &odak 'hoto()format, which has become the de facto standardforstoring digital photographs.

*ost digital cameras use (()sto capture images, though some of the newer less e%pensive cameras use(*O+chips instead.

A digital camera(or digicam) is a camerathat takes videoor stillphotographs, or both,

digitallb recordi!g imagesvia a! electro!icimage se!sor"

#ro!t a!d back o$ Ca!o! %o&er'hot A

Ma! compact digital still cameras ca! record so*!da!d movi!gvideoas &ell as still

photographs" Most +st ce!t*r cameras are digital"-.

Digital cameras ca! do thi!gs $ilm cameras ca!!ot/ displai!g images o! a scree!

immediatel a$ter the are recorded, stori!g tho*sa!ds o$ images o! a si!gle smallmemor device, recordi!g video &ith so*!d, a!d deleti!g images to $ree storage space"

'ome ca! crop pict*resa!d per$orm other eleme!tar image editi!g" The optical sstem
http://www.webopedia.com/TERM/S/store.htmlhttp://www.webopedia.com/TERM/S/store.htmlhttp://www.webopedia.com/TERM/D/digital.htmlhttp://www.webopedia.com/TERM/D/digital.htmlhttp://www.webopedia.com/TERM/D/digital.htmlhttp://www.webopedia.com/TERM/D/download.htmlhttp://www.webopedia.com/TERM/C/computer_system.htmlhttp://www.webopedia.com/TERM/C/computer_system.htmlhttp://www.webopedia.com/TERM/G/graphics.htmlhttp://www.webopedia.com/TERM/G/graphics.htmlhttp://www.webopedia.com/TERM/G/graphics.htmlhttp://www.webopedia.com/TERM/P/program.htmlhttp://www.webopedia.com/TERM/R/resolution.htmlhttp://www.webopedia.com/TERM/M/memory.htmlhttp://www.webopedia.com/TERM/M/memory.htmlhttp://www.webopedia.com/TERM/D/digitize.htmlhttp://www.webopedia.com/TERM/D/digitize.htmlhttp://www.webopedia.com/TERM/D/digitize.htmlhttp://www.webopedia.com/TERM/O/output_device.htmlhttp://www.webopedia.com/TERM/O/output_device.htmlhttp://www.webopedia.com/TERM/P/printer.htmlhttp://www.webopedia.com/TERM/P/printer.htmlhttp://www.webopedia.com/TERM/P/printer.htmlhttp://www.webopedia.com/TERM/L/laser_printer.htmlhttp://www.webopedia.com/TERM/L/laser_printer.htmlhttp://www.webopedia.com/TERM/S/scan.htmlhttp://www.webopedia.com/TERM/P/PhotoCD.htmlhttp://www.webopedia.com/TERM/F/format.htmlhttp://www.webopedia.com/TERM/F/format.htmlhttp://www.webopedia.com/TERM/D/de_facto_standard.htmlhttp://www.webopedia.com/TERM/D/de_facto_standard.htmlhttp://www.webopedia.com/TERM/C/CCD.htmlhttp://www.webopedia.com/TERM/C/CMOS.htmlhttp://en.wikipedia.org/wiki/Camerahttp://en.wikipedia.org/wiki/Camerahttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Photographhttp://en.wikipedia.org/wiki/Photographhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Digital_imagehttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Image_sensorhttp://en.wikipedia.org/wiki/Image_sensorhttp://en.wikipedia.org/wiki/Canon_PowerShot_Ahttp://en.wikipedia.org/wiki/Sound_recording_and_reproductionhttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Photographhttp://en.wikipedia.org/wiki/Digital_camera#cite_note-0%23cite_note-0http://en.wikipedia.org/wiki/Digital_camera#cite_note-0%23cite_note-0http://en.wikipedia.org/wiki/Cropping_(image)http://en.wikipedia.org/wiki/Cropping_(image)http://en.wikipedia.org/wiki/Image_editinghttp://en.wikipedia.org/wiki/File:Canon_PowerShot_A95_-_front_and_back.jpghttp://en.wikipedia.org/wiki/File:Canon_PowerShot_A95_-_front_and_back.jpghttp://www.webopedia.com/TERM/S/store.htmlhttp://www.webopedia.com/TERM/D/digital.htmlhttp://www.webopedia.com/TERM/D/download.htmlhttp://www.webopedia.com/TERM/C/computer_system.htmlhttp://www.webopedia.com/TERM/G/graphics.htmlhttp://www.webopedia.com/TERM/P/program.htmlhttp://www.webopedia.com/TERM/R/resolution.htmlhttp://www.webopedia.com/TERM/M/memory.htmlhttp://www.webopedia.com/TERM/D/digitize.htmlhttp://www.webopedia.com/TERM/O/output_device.htmlhttp://www.webopedia.com/TERM/P/printer.htmlhttp://www.webopedia.com/TERM/L/laser_printer.htmlhttp://www.webopedia.com/TERM/S/scan.htmlhttp://www.webopedia.com/TERM/P/PhotoCD.htmlhttp://www.webopedia.com/TERM/F/format.htmlhttp://www.webopedia.com/TERM/D/de_facto_standard.htmlhttp://www.webopedia.com/TERM/C/CCD.htmlhttp://www.webopedia.com/TERM/C/CMOS.htmlhttp://en.wikipedia.org/wiki/Camerahttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Photographhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Digital_imagehttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Image_sensorhttp://en.wikipedia.org/wiki/Canon_PowerShot_Ahttp://en.wikipedia.org/wiki/Sound_recording_and_reproductionhttp://en.wikipedia.org/wiki/Videohttp://en.wikipedia.org/wiki/Photographhttp://en.wikipedia.org/wiki/Digital_camera#cite_note-0%23cite_note-0http://en.wikipedia.org/wiki/Cropping_(image)http://en.wikipedia.org/wiki/Image_editing


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&orks the same as i! $ilm cameras,tpicall *si!g a le!s &ith a variable diaphragmto

$oc*s light o!to a! image pick*p device" The diaphragm a!d sh*tter admit the correct

amo*!t o$ light to the imager, 0*st as &ith $ilm b*t the image pick*p device is electro!icrather tha! chemical"

Digital cameras are i!corporated i!to ma! devices ra!gi!g $rom %DAsa!d mobilepho!es(called camera pho!es) to vehicles" The 1*bble 'pace Telescopea!d other

astro!omicaldevices are esse!tiall speciali2ed digital cameras"

o

Digital Cameras - A beginner's guide

byBob Atkins

Digital Camera Basics - A primer

Digital cameras are confusing to a lot of new users. In thisbasic guide to digital

camera technologywe hope to try to give digital beginners at least some basis to use in

deciding which digital camera is appropriate for them. When shopping for a digital

camera it's at least good to know what the basic terms like white balance, pixel,ppiand

dpimean and how they affect image and print uality. It's also important to know the

difference between things like optical zoomand digital zoomas well as the advantages

and disadvantages between storage formats such as Compact Flash!"#$,Microdrives,

Sony Memory Stick,Secure Digital!%D$, Multimediaand camera interface technologies

such as US !"!, US #"$andFirewire %&&& !'()"

Pixels

A pi&el is a contraction if the term PIcture ELement. Digital images are made up of small

suares, ust like a tile mosaic on your kitchen or bathroom wall. (hough a digital

photograph looks smooth and continuous ust like a regular photograph, it's actually

composed of millions of tiny suares as shown below.
http://en.wikipedia.org/wiki/Film_camerahttp://en.wikipedia.org/wiki/Film_camerahttp://en.wikipedia.org/wiki/Diaphragm_(optics)http://en.wikipedia.org/wiki/Personal_digital_assistanthttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Camera_phonehttp://en.wikipedia.org/wiki/Hubble_Space_Telescopehttp://en.wikipedia.org/wiki/Astronomyhttp://www.bobatkins.com/http://www.bobatkins.com/http://en.wikipedia.org/wiki/Film_camerahttp://en.wikipedia.org/wiki/Diaphragm_(optics)http://en.wikipedia.org/wiki/Personal_digital_assistanthttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Camera_phonehttp://en.wikipedia.org/wiki/Hubble_Space_Telescopehttp://en.wikipedia.org/wiki/Astronomyhttp://www.bobatkins.com/


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*n the le+t the +ull image, on the right the area in the red suare magni+ied to show

individual pixels

)ach pi&el in the image has a numerical value of between * and + and is made up of

three color channels. %o for e&ample a pi&el could be -/red, 0/green and 1+/blue and it

would then look like this . If it was 10+/red, +/green and 1+/blue, it would look like

this . (here are over 10 million possible combinations using this scheme and each one

represents a different color. "omputer savvy readers will note that each color in this

scheme can be represented by an 2/bit number !byte$, so the color of each pi&el is defined

by three color bytes. (his scheme can be e&panded, for e&ample to use 10/bits !two 2/bit

bytes$ for each color. Images using three 2/bit values are sometimes called #)-bit color

images. Images using three 1+/bit values for color definition are called '.-bit color

images, and those using three 10/bit values are called )/-bit color images.

Pixel Count

3ne of the main ways that manufacturers categori4e their digital cameras is in terms of

pixel count. What this is is the number of individual pi&els that go into making each

image. (oday this number varies between 1 million !! Megapixel$ to around 15 million

!!) Megapixels$. A million pi&els is abbreviated to 67, so a 167 camera has 1 million

pi&els and a -67 camera has - million pi&els. "urrently most popular consumer digital

cameras have between +67 and 67. A -67 camera can make e&cellent 58&08 prints

and very good 8&8 prints. If you intend to make lots of 28&1*8 prints, then perhaps a


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567 or 67 camera would be a better choice. %ometimes two numbers are given, total

pi&els and effective pi&els. (otal pi&els count every pi&el on the sensor surface. 9sually

the very edge pi&els aren't used in the final image. )ffective pi&els are the number of

pi&els actually used in the image after the edge pi&els have been dropped.

-67 567 67

:argest Image !typical$ +*52 & 1-0 +++ & 11+ +;+ & 1;55

7rint si4e at -+*dpi 0.8 & 5.28 .18 & .58 2.18 & 0.18

7rint si4e at +5*dpi 2.8 & 0.58 ;.8 & .18 1*.28 & 2.18

0ypical maximum image size vs" nominal 1ixel Count" See below +or comments on dpi

and print size

Aspect Ratio

(he aspect ratio of a camera is the ratio of the length of the sides of the images. #or

e&ample, a traditional -mm film frame is appro&imately -0mm wide and +5mm +. %ome

digicams use the same aspect ratio for their digital images. #or e&ample most digital %:?

!single lens refle&$ cameras have a ->+ aspect ratio. - aspect ratio. #or e&ample a monitor with a 2**&0** display has a 5>- aspect ratio.

With this in mind, most consumer level digicams use a 5>- aspect ratio for their images.

Sensor Size

(he si4e of the digital sensor element !which is euivalent to the si4e of the negative for

film cameras$ is pretty small in all consumer digicams / typically around the si4e of a

fingernail !and a small fingernail at that@$. As I said above, a -mm film frame is +5mm

high by -0mm wide but most digital cameras use sensors very much smaller than this.


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1C+.8 5>- .- 5.*

1C+8 5>- 0.5 5.2

1C1.28 5>- .+ .-

+C-8 5>- 2.2 0.0

18 5>- 1+.2 ;.0

5C-8 5>- 12.* 1-.

)3% 1*D ->+ ++.* 1.*

6ost of the current small 67 digital cameras use 1C1.28 sensors which are about mm &

mm. (hey have an area +& smaller than -mm film and about ;.& smaller than a small

sensor digital %:? like the "anon )3% 1*D. ou might wonder why sensor si4e matters

and that's a pretty comple& issue. (he bottom line is that, for a given pi&el count, the

larger the sensor !and hence the larger the area of the individual pi&els$ the better the

image uality and the lower the noise level. While large sensor cameras like the )3% 1*D

can operate at the euivalent of I%3 -+** !though the image does get noisy$, many

consumer digicams with small sensors cannot operate above I%3 5** before the noise

becomes e&cessive. #or a full treatment why all this is so, see my article here on photo net

titledSIZE MATTES

Another factor in uality here is that small sensors tend to be of a different type than

large sensors. %mall sensors, and the sensors used on all consumer digital cameras, use a

scheme which can read the data from the sensor in real time using a scheme called

8interline trans+er8 and the ""D electronics control e&posure rather than a mechanical

shutter. :arge sensors used on more e&pensive Digital %:?s are often of a different

design known as+ull +rame/ which doesn't refer to their si4e, but their design / and

which reuire the use of a mechanical shutter. (hey don't read out and the display the

data in real time, only after the e&posure so they can't give real time :"D displays or

record video. (he advantage of this scheme is that the whole pi&el area can be used to

capture light while interline trans+er""Ds use part of each pi&els to store charge. %ince

smaller pi&el areas generate more noise and interline trans+er""Ds are not only smaller

to start with but use some of their pi&el area for charge storage, their noise level is
http://photo.net/equipment/digital/sensorsize/http://photo.net/equipment/digital/sensorsize/http://photo.net/equipment/digital/sensorsize/


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significantly higher. %o the smaller interline transfer sensors in consumer digital cameras

yield lower uality images than those used in higher end D%:?s, they can do more

8tricks8 like recording video clips and giving a live image display on their :"D screen.

(he lack of a mechanical shutter also makes the cameras cheaper and simplifies

construction.

%mall sensors mean that short focal length lenses are needed to give the same field of

view as cameras using larger sensors or -mm film. %o, for e&ample, a typical consumer

digicam may need a mm lens to give the same view as you would get using a -mm focal

length lens on a -mm camera. (his has conseuences on depth of field and means that

most consumer digicams have a vary large depth of field. =reat if you want everything in

focus, not so great if you want a blurred background. (his is covered in detail in my

article here titledDI!ITAL DEPT" #$ $IELD

White Balance

With film you can buy 8daylight balanced film8 for shooting outdoors or 8tungsten

balanced film8 for shooting indoors under normal domestic lighting !not fluorescents@$. If

you use daylight film under tungsten light the images will be very yellow. If you use

tungsten film in daylight the images will be very blue. With film you have to correct for

the 8color temperature8 of the light using filters or by the right choice of film.

With digital you can pick your white balanceto suit your light source, so that white looks

white, not yellow or blue. ormally there is an automatic setting and the camera decides

what white balance setting to use.


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where the camera will pick from I%3 1**, I%3 +** and sometimes I%3 5**, depending

on the light level and the mode in which the camera is operating.

Digital Zoom and ptical Zoom

6ost cameras have both optical 4oom and digital 4oom. 3ptical 4oom works ust like a

4oom lens on a film camera. (he lens changes focal length and magnification as it is

4oomed. Image uality stays high throughout the 4oom range. Digital 4oom simply crops

the image to a smaller si4e, then enlarges the cropped portion to fill the frame again.

Digital 4oom results in a significant loss of uality as is clear from the e&amples below.

It's pretty much a last resort, and if you don't have it in camera, you can do a similar ob

using almost any image editing program.

Comparison o+ optical zoom and digital zoom

!P"#$ %&'' and RAW

(he si4e of the digital file corresponding to the image which the camera produces

depends on the pi&el count. In most consumer digicams each pi&el generates - bytes of

data !so called 82/bit data8$. 3ne for red, one for green and one for blue. (his means that

a -67 camera, which has - million pi&els, generates ; million bytes of data, or ;6B

!megabytes$. A few cameras can generate e&tra data for e&tra uality, and some of these


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cameras generate files which correspond to + bytes of data for each color !810/bit8$, so a

-67 camera which is capable of generating 10/bit data will produce an 126B image file.

ow these files are pretty big and they can be compressed uite a lot without a significant

drop in uality. (his is where E7)= !Eoint 7hoto )&perts =roup$ comes in. E7)= is an

algorithm designed to work with continuous tone photographic images$ which takes

image data and compresses it in a lossy manner !this means you do lose some

information$. (he more you compress, the smaller the file but the more information you

lose.


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*n the le+t, !$2! 31&4 compression" *n the 5ight )$2! compression"

Uncompressed the image would look virtually identical to the !$2! 31&4 on the le+t"

With 1*>1 compression the 2/bit files generated by a -67 camera would be ;**Gbytes in

si4e rather than ;6bytes, which is a big saving with little uality loss. (he smaller files

take up much less storage space and are much faster to send between computers or from

the digital camera or memory card to a computer.

(here are also lossless ways of saving files using (I## !(agged Image #ile #ormat$ .

(hese keep all the original information, but at the cost of much bigger files. (I## files can

be compressed in a non/lossy way, but they don't get very much smaller. #or e&ample,

compare the file si4es for the rabbit image above> (I## files can also be used to save 10/

bit data !those these files are twice the si4e of 2/bit data files$, E7)= files can only save 2/

bit data.

9ncompressed (I## "ompressed (I##E7)= at 1*>1

compression

E7)= at 5*>1

compression

10.1 Gbytes 1.0 Gbytes 1.5 Gbytes 5. Gbytes

%ome cameras offer a third option, that of saving the actual data generated by the sensor

in a proprietary format. "anon calls their version of this 8?AW8, ikon call it 8)#8.

(hese files are compressed, but in a non/lossy manner. (hey are significantly smaller

than euivalent (I## files, but larger than E7)=s. (ypically they achieve a compression

of around 0>1 using 10/bit data, so files are 1C0 the si4e of euivalent (I## files. (he only

disadvantage of these formats is that the image must be converted to either E7)= or (I##

for most software to be able to display them. (he conversion is uite a comple& process

and can be time consuming if you have a lot of images to convert and a 7" that's not very

fast. %ince the ?AW and )# formats contain more information than E7)=s !and in fact

often more than (I## files$ you can do some degree of e&posure compensation during

conversion to E7)= to rescue otherwise improperly e&posed images. ou can also make

white balance corrections during conversion, so if you shot with the wrong white balance,

you can fi& your error.

Display$ Printing$ DP& and PP&

(here's lots of confusion here so I'll try to go slowly@

When you display a digital image on a monitor, the only thing that determines the si4e of

the image is the pi&el count and aspect ratio. D7I and 77I !and I'll e&plain them later$

mean absolutely nothing. If your image is a 52*Gbyte file which is 2** pi&els wide by


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0** pi&els wide, it will display as a full screen image if you are using an 2**&0** display.

It doesn't matter if your D7I is set to 1 or 1*** or if your 77I is set to 1 or 1***. (his is

1**H true as far as web display goes and as far as any monitor display goes / unless some

software intervenes. #or e&ample the I)0 browser will take large images and resi4e them

so they fit on the screen.


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(here are uite a few different !and incompatible$ memory cards used in digital cameras.

"ompact #lash !"#$ / (he original memory card. 5+mm & -0mm & -mm. %omewhat

larger than the others, but used on all high end D%:?s. Available in capacities up to

+=B. (here are also miniature hard drives !6icrodrives$ with almost the same form

factor as "# cards !"# type II, mm thick$$ which are available in capacities from

-5*6B to 5=B. 6icrodrives used to be cheaper than solid state "# cards, though there

is not a big difference today up to about 1=B. (he 5=B 6icrodrives are actually cheaper

than the +=B "# cards though. 3f course prices change pretty fast these days@ 3verall

"# cards tend to be cheaper than any of the other forms of solid state memory / though

this too could change. "# cards and microdrives contain their own disk controller, so

that makes the camera electronics simpler.

%ecure Digital !%D$ / ery small / about +5mm & -+mm and +mm thick. (hey have a

built in write protect switch to prevent accidental erasure and certain encryption

capabilities of little interest to digital camera owners.

6ultimedia / %ame si4e as %D but with less features and no encryption capability.

(here are some that can be used in some %D cameras but they aren't 1**H compatible

with %D cards in all applications.

%mart 6edia / (hinner than "# cards, but lacking an on/card memory controller.

Despite the name, they're pretty dumb@

6emory %tick / Introduced by %ony and used only by %ony!$

JD / Developed and used by #ui, 3lympus and (oshiba / even smaller than %D.

+*mm & +mm by 1.mm thick

Is there any real difference in performance o, not really. (he "# cards are the cheapest

per megabyte and are available in higher capacity models than the other !of course that

may change with time$. 6ost high end D%:?s use them. (he smaller cards tend to be

used in the smaller consumer digicams. (here's really no reason to pick a camera with

one type over another unless you have multiple cameras or other devices !67- players

for e&ample$ which also use memory cards / then it's convenient if they can share cards.

It may also be difficult !andCor e&pensive$ to find really high capacity cards !1=B and up$

in formats other than "#, but that's probably not a concern for most digicam users.

(he following table gives the appro&imate number of shots you can e&pect to get using

low E7)= compression using various pi&el count cameras in conunction with various

si4ed memory cards at the lowest I%3 speed settings of a typical camera. (he e&act


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numbers depend on how much compression the camera applies and the I%3 speed used.


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digital cameraa camera that stores images digitally rather than recording them on film

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