医学成像与通信协议DICOM影像在各种显示介质上的一致性学术报告课件

1、DICOM Singapore Seminar:Consistent Presentation of Images:The Grayscale Image Presentation Problem: The appearance of grayscale images displayed on different types of softcopy display devices or printed on different types of hardcopy output devices has often been inconsistent. Optimal image viewing

2、parameters (e.g. window/ level) selected on one device appear different when displayed on a different deviceDevice capabilities/ characteristics vary - the same number of gray levels cannot be rendered or perceived on different devicesDisplayed images look different from printed imagesotherThe Grays

3、cale Consistency Problem: Problems of Inconsistencymass visiblemass invisibleVOI chosen on one display deviceRendered on another with different displayMass expected to be seen is no longer seenSlide Provided by David Clunie, Quintiles Intelligent ImagingProblems of Inconsistency0.51.51.03.0Not all d

4、isplay levelsare perceivable on alldevicesSlide Provided by David Clunie, Quintiles Intelligent ImagingProblems of InconsistencyDigital ModalityLaser PrinterPrinted images dont looklike displayed imagesSlide Provided by David Clunie, Quintiles Intelligent ImagingCauses of InconsistencyGamut of devic

5、eMinimum/maximum luminance/densityCharacteristic curveMapping digital input to luminance/densityShapeLinearityAmbient light or illuminationTowards a Standard DisplayCant use absolute luminance since display capabilities differentCant use relative luminance since shape of characteristic curves varySo

6、lution: exploit known characteristics of the contrast sensitivity of human visual system - contrast perception is different at different levels of luminanceHuman Visual SystemModel contrast sensitivityassume a target similar to image featuresconfirm model with measurementsBartens modelGrayscale Stan

7、dard Display Function:Input: Just Noticeable Differences (JNDs)Output: absolute luminancePrinter Calibration Tools (Densitometer)Perceptual Linearization.01.1110100100002004006008001000Grayscale Standard Display FunctionJND IndexSame number of Just Noticeable Difference = Same perceived contrastDesp

8、ite different changein absolute luminanceSlide Provided by David Clunie, Quintiles Intelligent ImagingMonitor Characteristic CurveMonitor Characteristic Curve0.010.110100050100150200250300Digital Driving LevelAmbient LightSlide Provided by David Clunie, Quintiles Intelligent ImagingStandardizing a D

9、isplay0.1110100050100150200250DDL or P-ValuesStandardCharacteristic CurveSlide Provided by David Clunie, Quintiles Intelligent ImagingStandardizing a DisplayMapping P-Values to Input of Characteristic Curve (DDLs)050100150200250300050100150200250300P-ValuesDDLSlide Provided by David Clunie, Quintile

10、s Intelligent ImagingTo Achieve Consistent Presentation of Images, the DICOM Standard Defines:Basic Print Management with Presentation Look Up Table, for controlling the consistent appearance of preformatted images on printed outputGrayscale Softcopy Presentation State, for controlling the consisten

11、t appearance of images on softcopy displayBasic Print Management Meta SOP ClassPrint (SCU)Print (SCP)Association Negotiation - “Contract Agreement”Agreed set of SOP Classes and Transfer Syntaxes( Basic Print Meta SOP Class)Film SheetBasic Print Meta SOP Class consist of four SOP Classes(Film Session

12、, Film Box, Image Box, and Printer)N-Create (create film sheet, format printer)N-Set (place images on film sheet)N-Action (request to print the film sheet)N-Event-Report (status of the printer)Slide Provided by Don Van Syckle, Merge Technologies Inc.Example: A Radiologist “Flips” Chest XRAY Image on

13、 Softcopy DisplaySuspected areaExample Continued: Radiologist Magnifies Chest XRAY Image, Pans to Upper Right Hand Quadrant and Adds an AnnotationComposite object containing the image display settings parametersComposite object links to one or more images (Series, filters); stored using same Study I

14、nstance UID (same Storage SOP Class!)Uses regular Storage services (C-STORE); uses Query/Retrieve servicesGSPS SOP Instances are immutable: changes require a new SOP Instance UIDNote: generation and specific application of GSPS is outside the scope of DICOM, but not outside the scope of IHE (e.g. Vi

15、rtual Image Set Split)Grayscale Softcopy Presentation State:IEModuleUsagePatientPatientMStudyGeneral StudyMPatient StudyUSeriesGeneral SeriesMPresentation SeriesMEquipmentGeneral EquipmentMPresentationPresentation StateMModality LUTC - Required if to be appliedMaskC - Required if multi-frame and to

16、be appliedVOI LUTC - Required if to be appliedSoftcopy Presentation LUTMGraphic AnnotationC - Required if to be appliedSpatial TransformationC - Required if rotation, flipping or magnification are to be appliedDisplayed AreaMDisplay ShutterC - Required if to be applied and the Bitmap Display Shutter

17、 Module is notpresentBitmap Display ShutterC - Required if to be applied and the Display Shutter Module is not presentOverlay PlaneC - Required if to be applied or the BM Displ. Shutter Module is presentOverlay/Curve ActivationC- Required if image contains curve or overlay which is to be displayedGr

18、aphic LayerC - Required if Graphic Annotation or Overlays or Curves are to be appliedSOP CommonMGSPS Module Table:What about color ?Consistency is harder to achieveNot just colorimetry (i.e. not just CIELAB)Gamut of devices much more variableGreater influence of psychovisual effectsExtensive standards efforts e.g. ICCDICOM is defining color presen