JPEGs
When produced in camera JPEG files are generated by
using the information in the camera called firmware to
createacompresseddatafile.Thecamerawillrenderthe
dataandformtheimagebydiscardingsomeinformation
thatitseesasexpendable.JPEGsaredesignedtobeused
immediately and can be printed with little or no
manipulationasthelevelsofexposure,contrastandcolour
correctionhaveallbeenpredeterminedinsomewaybythe
settingsinthecamera,eitherbytheuserorbythecamera
itself.
Thereareobviouslimitationswhenusingthis methodof
imagecapture.Thephotographeriseffectivelygivingthe
majorityofthecontrolovertothecamera,allowingitto
makethefinalcreativechoices.Althoughthecameraisa
sophisticatedandextremelypowerfultoolitisnotableto
see an image accurately and sensitively in the way the
human eye would. For example subtleties of light and
shade,alovelywarmskintone,andacreativeflairarenot
basedonaveragesandbaselinesbutratheronminutelittle
tweaks and adjustments that make itvisually correct or
pleasing.
JPEG files by their nature do not handle manipulation
particularly well, and they will degrade and deteriorate
fairlyrapidlyifmanychangesaremade.Withafarlower
dynamicrangethanthatofacomparableRAWfilefrom
the same camera, the JPEG is much more sensitive to
change when you are playing with tools that affect
exposure and colour balance, and as such getting the
required quality and output is much less predictable.