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1、(医学影像物理学)03-数字图像IWhatisImage?ImageImageofobjectMathematicFunctionPicturePhoticImageContinueFunctionDiscreteFunctionInvisibleImage图像与影像DigitalImage?Sincecomputersstoredataandunderstanddatainanumericalform,wecansaythatanimageisanumericalrepresentationofa“picture”–asetofnumbersinterpretedbytheco
2、mputerwhichcreatesavisualrepresentationthatisunderstoodbyhumans.25525519914397187321234232211244198179123941953243521332112532172346818597131227111426Graphics?TrueColorandPseudocolor24truecolorand32truecolorPseudoclor:Thecolorwegivetoaimagetoshowtheinformation.inwhichdifferentcolorlevelrepres
3、entdifferentdata.WhatisgrayGrayScalepixelvaluesrepresentalevelofgraynessorbrightness,rangingfromcompletelyblacktocompletelywhite.Inan8-bitGrayScaleimage,apixelwithavalueof0iscompletelyblack,andapixelwithavalueof255iscompletelywhite.Avalueof127representsagraycolorexactlyhalfwaybetweenblackandw
4、hite(medium-gray),andapixelvalueof64hasagraycolorhalfwaybetweenmedium-grayandblack.ScaleNumberGreylevelWeusegreyleveltorepresentbrightnessinformationinapicture.Ifonepictureonlyhave2purecolors:whiteandblack,itsinformationisverylimited.Toshowmoreinformation,wecanadoptgreyImage,thatUsuallyis6gre
5、yscale(26,64level)or8greyscale(28,256level).256shadesofgray4grayscale6grayscale8grayscaleAlthoughGrayScaleimageswithbitdepthsof2,4,6,12,16and32exist,8BitGrayScaleimagesarethemostcommon.Thisisfortworeasons:1)its1-byte-per-pixelsizemakesiteasytomanipulatewithacomputer,and2)itcanfaithfullyrepres
6、entanygrayscaleimagebecauseitprovides256distinctlevelsofgray(thehumaneyecandistinguishlessthan200graylevels).FileFormatBMP:微软Windows设置的标准图像格式GIF:GraphicInterchangeFormat图形交换格式JPEG:JointPhotographicExpertGroupTIF:JPEG2000:DICOM文件计算机中存储图像文件的格式。面向对象统一标识符标签与属性BasicConceptionofImageBrightnessInten
7、sityContrastGray(GrayLevel)DefinitionResolutionCoordinateHueSaturationColorTemperaturePixelsareidentifiedbytheirpositioninagrid(two-dimensionalarray),referencedbyitsrow(x),andcolumn(y).CoordinateSystemImage:Pixelarray数字图像的形成信号转换过程感知抽样量化图像感知和获
